free food thought for

Grazing Winter Crops Roadshow

Workshop NotesMarch 2008

Free Food Thoughtfor



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Intent of these workshop notes

These notes bring together the latest results from the Grain & Graze Program on grazing winter crops.

They combine experimental results, producer information and observations from areas across Australia and identify insights and consequences of grazing winter crops on mixed farms. The notes are not intended to report on all the information that exist on grazing winter crops but rather to support the events being conducted by Grain & Graze in March 2008.

Winter crops offer many opportunities beyond sowing and harvesting for grain. There is opportunity for grazing and grain, but farmers need to know how to exploit the opportunities grazing provides while minimising any negative effects.

Grazing winter crops can provide a ‘free lunch’, but only if the advantages gained from grazing are not outweighed by the impact the grazing has on silage or hay, crop yields, grain quality and the longer term effects on weeds and the soil.

The circumstances on every farm will be different which means there is a vast range of possible combinations. There is no recipe to grazing winter crops. Instead there are some general rules that help farmers and advisors to appreciate the impacts and benefi ts from grazing different crops, at different times and for different durations and intensities. Each individual will need to consider these pros and cons and determine the best fi t for their farm.

The workshop notes are structured in a way to answer the questions farmers commonly ask about grazing winter crops.

The notes have been compiled by Cam Nicholson with contributions from people in the following Grain & Graze regions

Avon (David Kessell, Shahajahan Miyan, Sam Clune, Barb Sage, Tenielle Martin)•

Corangamite / Glenelg Hopkins (Geoff Dean, Simon Falkiner, Frank Mickan, • Cam Nicholson and David Watson).

Eyre Peninsula (Brian ‘Smokey’ Ashton, Emma McInerney, Tim Prance) •

Mallee (Tim Prance, Zubair Shahzad)•

Murrumbidgee (Katrina Sait)•

Northern Ag (Janette Drew, Phil Barrett-Lennard, Tim Wiley)•

National support•

CSIRO (Hugh Dove, Libby Salmon) –

Consultants (Andrew Bathgate) –

Editing (Sefton & Associates) –

Design & Illustration – Marg McKenzie

Printing – Adams Print, Geelong

Product Code – PR081446

DisclaimerThe advice provided in these notes is intended as a source of information only. Grain & Graze does not guarantee that these notes are without fl aw of any kind or is wholly appropriate for your purposes and therefore disclaims all liability for any error, loss or other consequence which may arise from you relying on any information in this publication.

Copying of these notes and information contained within Information in these notes may be reproduced in whole or part, as long as due recognition is given to the Grain & Graze Program.

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Contents1. The opportunities grazing winter crops provide (why do it?) 1

1.1 The grazing opportunity 5

1.2 Calculating the amount of extra feed 5

1.3 How can the grazing opportunity be valued? 7

1.3.1 Valuing the dry matter eaten 7

1.3.2 Valuing the liveweight gain 8

1.3.3 Valuing the extra stocking rate 9

1.3.4 Valuing the extra pasture grown when the crops are grazed 11

1.3.5 Valuing the whole farm impacts 12

1.4 Balancing the benefi ts and the cost 14

1.5 Grazing crops - making the decision 15

1.6 What is on the horizon with grazing crops? 17

2: What and how to do it (agronomy at the paddock scale) 212.1 When to sow 25

2.2 What to sow 26

2.3 How much dry matter is produced? 28

2.4 Options for increasing dry matter production up to growth stage 30 30

2.5 What is the quality of the dry matter? 33

2.6 Grazing 34

2.7 Suitable livestock 43

2.8 Use of herbicides 43

3: The effects of grazing (impacts at the paddock scale) 453.1 Variability in the growing season 45

3.2 Effect of grazing on crop maturity 47

3.3 Effect of grazing on grain yield 49

3.4 Effect of grazing on grain quality and grain characteristics 52

3.5 Effect of grazing on silage, hay and stubble 53

3.6 Livestock response to grazing (and animal health issues) 56

3.6.1 Liveweight 56

3.6.2 Animal health 58

3.7 Grazing and the impact on crop weeds 59

3.7.1 So what does this mean for grazing crops? 60

3.8 Grazing and the impact on crop diseases 64

Appendix 1: Cereal growth rates by Grain & Graze region 66

Appendix 2: Ready reckoner of crop height and estimated dry matter 68

Appendix 3: Dry sheep equivalent (DSE) rating for different classes 69 of livestock

Appendix 4: Budget sheet to calculate the number of stock needed 70 to graze a specifi ed herbage mass over a given number of days

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1. The opportunities grazing winter crops provide (why do it?)Winter crops offer a range of opportunities to the farming system. The most obvious opportunity in a mixed farming system is to graze the crop when it is tillering, eating the leaves at the time of year when other feed is often in short supply. Once grazing is completed, there may also be opportunities to use the crop for silage, hay, grain and straw. Winter crops are also being considered as an alternative forage source to traditional pasture as variability in climate becomes more challenging. The alternative uses provide an opportunity to make different decisions depending on the season (see Grazing crops as a drought strategy to minimise seasonal risk in Western Australia).

Grazing crops as a drought strategy to minimise seasonal risk in Western AustraliaDue to drought, some farmers in the previously reliable northern wheat belt of Western Australia are turning to winter crops to reduce production risk. They are increasing the area sown to crops, but are reducing up-front inputs and therefore costs. As the season unfolds they are making tactical decisions about further inputs (e.g. nitrogen and post emergent weed control) and whether to graze some crops.

If the early winter rains are good then annual pasture paddocks will produce suffi cient feed which means the crops are not needed for grazing. The grain crops are then taken through to harvest ungrazed. However, if early rains are poor then cropped paddocks will be grazed to ensure there is enough feed for livestock without additional hand feeding. Grazing will also control the seed set of weeds, such as wild radish, without the need for post emergent herbicides.

The timing and duration of grazing is also fl exible. A single grazing in the tillering to stem elongation phase will not reduce grain yield, and may even increase yield in a dry year as there is less leaf canopy in winter and so more soil moisture remaining for grain fi ll in spring. If the season turns into a true drought, then livestock will continue grazing crops for the remainder of the season. These crops would have failed for grain production anyway, but provide valuable feed for livestock. The grazed crops also provide better protection from wind erosion than volunteer pastures over the following summer.


The reference to some crops being ‘dual purpose’ arises because the crop can be used successfully in more than one way. However just because a crop variety may not have the tag ‘dual purpose’ does not mean it cannot be used for grazing and grain (see What’s the difference between dual purpose crops, winter wheat and spring cereals?).

The main options for grazing a winter crop are presented in fi gure 1. This booklet contains detailed information on the areas shaded.

What’s the difference between dual purpose crops, winter wheat and spring cereals?As the name suggests, dual purpose crops can be used for more than one activity, usually grazing over winter, followed by hay or grain production. The dual purpose tag comes from the ability of the crop to recover after grazing.

Oats have traditionally been recognized as dual purpose, but recently some wheat cultivars have been bred to remain vegetative (leafy) for a long period after sowing, enabling signifi cant periods of grazing and then grain production. The long period of vegetative growth is determined by a gene bred into the plant that requires exposure to cold conditions to trigger commencement of head development. This requirement for a cold trigger gives rise to the term ‘winter habit’.

Cereal varieties with winter habit often grow slower than non-winter habit cultivars early in the season, but the dry matter difference at the end of winter can be reduced if crops are sown early - in March or early April. The time when the plant changes from vegetative growth is also more predictable because of the need for exposure to cold temperatures.

Just because a plant does not have winter habit does not mean it cannot be grazed and then recover successfully. However the opportunity to graze is reduced and the time when the plant changes from vegetative growth is less predictable.



Figure 1: Common opportunities from winter crops

The common opportunities presented in fi gure 1 are not the same in every region. Variability in the growing season means some opportunities cannot be realised or if they are undertaken they can have a negative impact on subsequent options.

A long growing season allows the full potential of dual purpose crops to be realised. With a long growing season, crops can be sown early in the year (March or April) and there is still suffi cient moisture in most years to allow crop recovery and grain fi ll after grazing.

A shorter growing season, characterised by unreliable opening and/or fi nishing rains, means the same principles and impacts of grazing winter crops may not apply. This variability in growing season will infl uence:

The time of sowing and variety chosen

The timing and duration of grazing

The ability of the grazed crop to recover and be used for silage, hay or grain production.

The implications of the variable growing season for different Grain & Graze regions are summarised (table 1).

Sowing

Grazing Silage

Hay

Graze standing crop

Graze stubble

Bale straw

Grain


Table 1 Characteristics of the growing season and implications for grazing winter crops

Region Time of sowing Opportunity for grazing

Recovery after grazing

Avon (Sthn WA) Late April to beginning of June

Limited to about two to four weeks in low rainfall areas, four to six weeks in higher rainfall areas.

Grain yield usually not affected if grazed early.

Grazing at late tillering likely to affect yield unless favourable spring fi nish.

Southern Vic, SE South Aust and Tasmania

(Corangamite / Glenelg Hopkins)

Usual May sowing. Feb/ March sowing unreliable except with irrigation. Often reliable in Tas.

Limited to about six to eight weeks to avoid grain yield loss. Drymatter for grazing often small. 10 weeks in Tas.

Generally good unless warm dry conditions in early Spring. Silage or hay is possible. Grain fi ll is generally not affected unless dry late spring.

Upper Eyre Peninsula (SA)

Usually May

Early / dry sowing in March / April

Limited to four weeks if targeting grain

Grain yield usually affected, except under very favourable seasons

Lower Eyre Peninsula / Kangaroo Island, (SA)

May / June Four – six weeks if targeting grain

Not affected if grazed early. Grazing at late tillering likely to affect yield unless favourable spring fi nish.

Mid North & Yorke Peninsula, SA

May / June Limited to about six to eight weeks to avoid grain yield loss.

Grain fi ll is generally not affected unless dry late spring.

Mallee (SA, Vic, NSW)

Usually May. Rare opportunity for early sowing but success relies on follow up rains.

Limited to about four to six weeks.

Affected in most years. Reduction in grain yield common even if grazing is completed before stem elongation.

Murrumbidgee (NSW)

Often in Feb / March because of adequate autumn rains.

Up to 10 weeks if sown early.

Generally good unless warm dry conditions in early Spring. Silage or hay is possible. Grain fi ll is generally not affected unless dry late spring.

Northern WA (Northern Ag Region)

Late April to the beginning of June

Limited to about two to four weeks in low rainfall areas, four to six weeks in higher rainfall areas.

One grazing in lower rainfall areas. Grazing twice can substantially reduce grain yields.

Stock can selectively graze out weeds in lupins and certain cereal varieties.

It is critical to appreciate the differences in regional characteristics so the opportunities and risks of grazing winter crops are understood before decisions are made.

Details about the agronomy and risk of grazing winter crops are presented in section 2 and 3 of these notes.

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1.1 The grazing opportunity

In the context of a whole farm, winter crops change the amount of feed available for grazing (i.e. it is increased). Just how this additional feed is captured and used to best advantage will depend on the individual.

The most common uses of this extra feed is to:

Fill a winter feed defi cit, avoiding underfeeding, reducing the need for supplementation or the need to sell stock at low prices (see case study 1)

Provide more feed so stocking rates can be increased to better utilise the spring surplus (see How do winter crops change feed supply and infl uence stocking rate?)

To ‘spell’ pastures from grazing, enabling them to ‘get away’ and reach pasture benchmarks for lambing or calving

Provide the opportunity to ‘punt’ and trade stock, by purchasing at times of low prices (see case study 2).

1.2 Calculating the amount of extra feed

The amount of dry matter (DM) available for grazing can be calculated if the type of crop, growth rate and days before grazing commences, are known. However it is important to use the appropriate regional growth rates, as variability in growth between regions can be substantial. For example, a barley crop sown in South West Victoria at the start of May would produce approximately 1200 kg/ha DM at the end of June (table 2). In contrast, the Northern Agricultural Region of Western Australia could produce as little as 450 kg/ha by the end of June, or as much as 1350 kg/ha, depending on the seasonal infl uence on growth rates. Average monthly growth rates for some regions are presented (appendix 1).

Case study 1

Grazing winter crops avoids the need to offl oad stockWayne Johnson, the Manager of “Warrambeen” in South West Victoria, decided to graze his winter crops for the fi rst time in 2007. Due to the late break and lack of suitable pasture, Wayne was confronted with having to sell 1500 merino weaners he had fed through the drought into a falling livestock market.

In consultation with Agronomist David Watson, Wayne decided to graze 148 hectares (ha) of Kosiuszcko short season triticale, followed by grazing two paddocks of red wheat (varieties 1077 and 1078). Grazing of the triticale commenced on May 4 when only 430 kg of dry matter per ha was on offer and grazing of the wheat fi nished on August 3.

The triticale had good early establishment and grew a bulk of feed early which we could use before we put the stock on the red wheat, which was slower to establish but grew the bulk of feed later,” he says.

By using the triticale, then the wheat, we were able to stagger our grazing and graze cereals for longer.”

The merino weaners gained 12.5 kg over this period and were sold in August for with an added value of $26.70 to $47.50/head.

Most of the triticale crop was cut for silage (9.2 tonnes/ha), with 40 ha taken through for grain. The grazed crop yielded 0.48 t/ha more grain than the ungrazed crop. Wayne believes that grazing delayed crop maturity by about a week and it is thought that this reduced the impact of frost on yield.


How do winter crops change feed supply and infl uence stocking rate?The MLA Feed Demand Calculator provides a snapshot of the change in feed supply and implications for stocking rate by grazing winter crops. The Feed Demand Calculator was developed to show visually the feed demand of your herd and/or fl ock across the year on a monthly basis. It also shows a pasture supply curve against which you can compare your feed demand.

Case study 2

Grazing winter crops give confi dence to purchase stockat low pricesThe additional production gained from sowing winter crops has enabled Kellie and Adam Walton at “Wurrook South” in South West Victoria to increase stocking rates by more than 10%.

In February 2007, during the height of the drought, the Walton’s purchased 1000 merino ewes cheaply with the intention of dramatically increasing the area of winter crops sown specifi cally for grazing. The crops would compensate for the anticipated poor pasture production in paddocks run down during the drought. The crops were sown solely

for grazing, with no specifi c intention of cutting hay or harvesting for grain.

A total of 150 ha of wheat and barley was sown in late March at 100 kg/ha in eight paddocks; to spread the dry matter production and allow rotational grazing.

Property manager, Tom Blackford, said all crops were grazed for the fi rst time at the two leaf stage in May with mobs of 700 and 1000 ewes. Once the crops were grazed ‘to the ground’ the stock were removed. Sheep went back onto the crops in mid June/early July when they were about 45 cm high.

One barley paddock was grazed three times then locked up and will be harvested for grain with an estimated yield of 2.5t/ha.

With the success of grazing winter crops in the farming syste, the Walton’s have plans to join up to 10,000 ewes by 2009.



Table 2 Calculation of anticipated feed available from barley sown at the start of May, South West Vic

Month Days in month

Estimated growth rate1

(kg DM/ha/day)

Feed on offer at end of month (kg/ha)

May 31 15 465

Jun 30 25 1215 (465 + 750)

A more comprehensive way to determine the implications of the extra feed provided from cropping paddocks is to use the MLA Feed Demand Calculator (see How do winter crops change feed supply and infl uence stocking rate?).1 This computer spreadsheet enables users to construct a whole farm feed profi le, including both crops and pasture. By choosing the crop type, area and grazing date, the impact on the monthly feed supply across the whole farm can be calculated.

Copies of the Feed Demand Calculator can be downloaded from the MLA website (hint: type ‘feed demand calculator’ in the search box).

1.3 How can the grazing opportunity be valued?

There are many ways to put a dollar value on the opportunity that grazing winter crops provide. Some possible options are presented and farmers will need to decide which option best suits their situation. These are:

Value the dry matter eaten on an energy basis and compare this to the equivalent energy supplied through grain or hay

Value the liveweight gain achieved through the grazing period

Value the stocking rate and assign a price per head or per hectare

Value the extra pasture grown while the crop is being grazed

Conducting a whole farm examination of costs and returns.

1.3.1 Valuing the dry matter eaten

This is the simplest way of valuing the grazing but is likely to overestimate the benefi ts. Firstly, most farmers are unlikely to feed a supplement to the equivalent energy value as that obtained from the crop. Secondly, this method assumes there would have been no alternative feed available for the stock when there may be pasture that can provide part of the livestock requirements.

1 Average monthly growth rates for different crops for different regions are presented (appendix 1).


To complete this calculation the following information is required:

Type of livestock and their dry sheep equivalent (DSE) rating

The number of animals grazed

The grazing duration

The value of the supplement to compare with

Changes in silage, hay or grain yields

Silage, hay or grain prices.

The assumptions used are:

Each DSE will eat the equivalent of 1 kg of DM per day

The energy content of grazed wheat is 12.5 MJ ME/kg and barley is 11.5 MJ ME/kg (Note: MJ = Megajoules, ME = Metabolisable energy)

The energy content of whole wheat is 13.0 MJ ME/kg and barley is 12.5 MJ ME/kg

Example: 600 late pregnant fi rst cross ewes graze a barley crop for 21 days compared to supplementary feeding wheat. There is no grain loss at harvest due to grazing and no post grazing fertiliser or weed control is needed.

Feed eaten: 600 ewes @ 2 DSE/ewe = 1200 kg eaten per day x 21 day = 25,200 kg

Energy in feed eaten: 25,200 kg @ 11.5 MJ ME/kg = 289,800 MJ ME

Equivalent barley eaten: 289,800 MJ ME/12.5 MJ ME/kg = 23.2 tonnes of grain

Equivalent value of barley: 23.2 tonnes of barley @ $250/tonne = $5,800

The estimated value of grazing the crop with the ewes was $5,800.

1.3.2 Valuing the liveweight gain

This method is appropriate where stock are grazed for an extended period so the change in liveweight can be determined. The following information is required:

The opening and closing liveweight of the animals

The opening and closing values (prices) of the animals

The additional costs associated with sowing the crop

Changes in silage, hay or grain yields

Silage, hay or grain prices.

Example: Fifty 250 kg steers graze a 20 ha winter wheat crop for 50 days. The steers gain 1.2 kg/head (hd) liveweight a day. The opening value is $1.90/kg, closing value is $1.70/kg and there is no grain loss at harvest due to grazing.



Opening weight: 250 kg

Opening value: 250 kg @ $1.90/kg = $475/hd

Closing weight: 250 kg/hd + 50 days x 1.2 kg/hd/day = 310 kg/hd

Closing value: 310 kg @ $1.70/kg = $527/hd

Change in value per head: $527 – $475 = $52 x 50 head = $2,600

The estimated value of grazing the crop with the steers was $2,600.

1.3.3 Valuing the extra stocking rate

This method requires a calculation of the amount of grazing achieved from the crop and assigning a value for each of the grazing days. The value of grazing will vary with regions, but dividing a typical gross margin per DSE by the number of days in a year will give an indicative value. For example the fi ve year average gross margin2 for enterprises in South West Victoria are:

Prime lambs $21.70/DSE or 6c/DSE/day

Wool sheep $15.30/DSE or 4c/DSE/day

Cattle $17.30/DSE or 5c/DSE/day.

The following information is required:

The number of animals and days the crop was grazed

A DSE rating for the animals

A value for each grazing day (agistment rates can also be used to calculate this fi gure)

Changes in grain yield due to grazing

Grain price.

Example 1: Fifty 250 kg steers graze a 20 ha winter wheat crop for 50 days. The stock are assigned a DSE rating of 9.5. Each DSE grazing day is valued at $0.05. There is no assumed loss in grain yield.

DSE grazing days: 50 hd x 50 days x 9.5 DSE/hd = 23,750

Grazing value: 23,750 DSE grazing days x $0.05/DSE grazing day = $1,187.50

The estimated value of grazing the crop with the steers was $1,188. This method can be taken further to compare the gross margins of grazing a crop to that of a conventional pasture.

2 South West Farm Monitor Project DPI, Hamilton. Average from 2001/2002 to 2005/2006


Example 2: Comparison of strip grazing a paddock sown to grazing oats and ryegrass compared to volunteer pasture (Binnu, WA, 2004. 190 mm rainfall).

Pasture Grazing methodTotal DSE grazing days/ha

DSE/ha/year

Self regenerating annual pasture Whole paddock 141 0.4

Sown ryegrass & grazing oats Strip grazing 2,617 7.2

Self regenerating annual pasture

Sown ryegrass & grazing oats

Carrying capacity 0.4 DSE/ha 7.2 DSE/ha

Income

Wool

Meat

$9.74/ha

$8.84/ha

$173.80/ha

$159.08/ha

Total income $18.58/ha $332.88/ha

Costs

Sheep

Pasture & fencing

$5.87 /ha

$10.00 /ha

$104.68 /ha

$130.86 /ha

Total costs $15.87/ha $235.54/ha

Net income $2.71/ha $97.34/ha



1.3.4 Valuing the extra pasture grown when the crops are grazed

Many farmers have commented that the greatest benefi t from grazing their winter crops has been the additional pasture grown which can then be used by livestock at a later stage. This deferment requires the additional pasture production to be valued. It is calculated by considering the benefi ts to the livestock enterprise from increases in available pasture, e.g. improved ewe condition, increased lambing, better lamb growth rates and higher ovulation rates.

Libby Salmon at the CSIRO Canberra modelled the value of different deferment periods for a merino and prime lamb enterprises in South West Victoria over a 48 year period. This analysis enabled seasonal variation and the subtle gains of increased reproductive benefi ts to be considered over a long period of time. The results are presented (tables 3 & 4).

Table 3 Change in pasture production and gross margin per DSE for different deferment periods for a self replacing merino enterprise in South West Victoria

Period crop grazed

(assumes all stock removed from pasture to crops)

Additional pasture available on August 1 from grazing crop

(kg DM/ha)

Additional pasture available on August 1 by grazing crops relative to continuous grazing of pasture

(%)

Change in merino enterprise gross margin by grazing crop relative to continuous grazing of pasture

(%)

15-31 May 70 6 7

1-14 Jun 110 10 6

15-30 Jun 160 16 7

1 Jul-14 Jul 180 18 7

15 Jul-31 Jul 290 30 10

1-30 Jun 330 34 12

15 Jun-15 Jul 480 49 15

1-31 Jul 550 56 17


Table 4 Change in pasture production and gross margin per DSE for different deferment periods for a prime lamb enterprise in South West Victoria

Period crop grazed

(assumes all stock removed from pasture to crops)

Additional pasture available on August 1 from grazing crop

(kg DM/ha)

Additional pasture available on August 1 by grazing crops relative to continuous grazing of pasture

(%)

Change in prime lamb enterprise gross margin by grazing crop relative to continuous grazing of pasture

(%)

15-31 May 50 3 3

1-14 Jun 70 4 3

15-30 Jun 110 7 3

1 Jul-14 Jul 100 6 6

15 Jul-31 Jul 150 9 11

1-30 Jun 200 12 7

15 Jun-15 Jul 240 14 11

1-31 Jul 260 15 16

The average gross margin for a prime lamb enterprise in South West Victoria is calculated at $21.80/DSE3. Therefore the opportunity to graze all livestock on winter crops for a month, say from June 15 to July 15 would increase gross margins by $2.40/DSE ($21.80/DSE x 11% increase = $2.40).

1.3.5 Valuing the whole farm impacts

This calculation is arguably the most meaningful to a farmer but requires very detailed calculations. A case study example for the whole farm impacts of grazing winter crops is presented (see case study 3).

3 South West Farm Monitor Project DPI, Hamilton. Average from 2001/2002 to 2005/2006



Case study 3

Effect of grazing winter crops on the most profi table enterprise mixWhole farm analysis by Andrew Bathgate for the Grain & Graze Program suggests that grazing winter crops can be profi table, but profi tabililty depends on a number of infl uences including: grain prices, potential yield loss through grazing, the proportion and type of crop grown and the ability to increase stocking rates to utilise the extra feed.

In this example a ‘typical’ 1000 ha mixed farm with four soil types in the Coolamon region of NSW (rainfall 450 mm/yr) is considered. The farm has a mix of crops (wheat, barley, canola and lupins) with the remainder under pasture and lucerne. Wool sheep are run on the property. The modeling spans 30 years.

The analysis has shown that grazing wheat is likely to increase farm profi t compared to no grazing for the same area of crop grown. If 500 ha of crop is sown, farm profi t is increased by approximately $8,000 by grazing (fi gure A). The analysis also shows that if a larger area of crop is sown, profi tability will decline unless the crop is grazed.

Figure A Responses of farm profi t to area of crop, with (green line) and without (orange line) grazing wheat, assuming a yield loss in grazing wheat of 10%. Wheat price $150/t, canola price $314/t, wool price 750 c/kg clean

The model also allows examination of the effect of changing commodity prices, yields and implication for stocking rates. In this example, the extra profi t requires stocking rates to increase from 11 DSE/ha to 14 DSE/ha.

Full reports about the model and regional analysis are available from Grain & Graze Regional Coordinators (http://www.grainandgraze.com.au).

120,000

80,000

100,000

60,000

40,000

20,000

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0 200 400 600 800 1,000

Area of Crop

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($/h

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1.4 Balancing the benefi ts and the costs

Grazing winter crops can have benefi ts but they may also come at a cost. The likelihood of the benefi ts and costs occurring will vary depending on regional characteristics, farm history and choices made during the cropping season. For example, in a region with a growing season that fi nishes early, the completion of grazing before stem elongation (recommended practice) may still result in a loss of grain yield. In contrast, a region with a good fi nish to the season may achieve an increase in grain yield, even though the grazing decisions at the time were identical.

It is critical for each farmer to evaluate the benefi ts and costs associated with grazing winter crops to help decide if the opportunities outweigh the risks. The possible benefi ts and costs are summarised in a farm balance sheet (table 5).

Table 5 Farm balance sheet on the possible benefi ts and costs associated with grazing winter crops

Possible benefi ts Possible costs

Grazing considerations

Feed from crop High quality dry matter allowing pastures to be spelled at period of peak demand

Pasture growth Grazing the crop allows the pasture to ‘get away’

Liveweight gain Positive weight gain but may require mineral supplementation

Cost of mineral, fi bre and/or energy supplementation

Stocking rate Whole farm stocking rates can potentially be increased, but it is often diffi cult to match stock numbers to the short grazing period

Requires purchase/breeding of extra livestock.

May require temporary fencing to achieve even grazing of the crop

Supplementary feeding

Should be reduced as the crop provides an alternative feed source

Animal health Reduced worm burden as pastures are free at peak contamination period

May get slight increase in mortalities

Soil compaction Grazing when wet may lead to increased pugging and soil structure decline

Crop Considerations

Grain yield May increase compared to no grazing by conserving soil moisture from earlier in the year that is used at grain fi ll

Yield will be decreased if grazing after growth stage 30. Yield may be reduced in short growing season areas or where the season fi nishes early

Grain quality Grazing will reduce protein levels in barley enabling the grain to reach malting quality

May require additional nitrogen inputs after grazing.



Possible benefi ts Possible costs

Hay / silage Will be reduced due to grazing

Stubble Stubble will be reduced which may help reduce sowing diffi culties where stubbles are not burnt

Reduces stubble if straw is to be baled. May increase soil exposure.

Crop maturity Will be delayed which may avoid exposure to late frosts and exposure to early rust infestions

Will be delayed which may expose crop to moisture stress late in the season

Fertiliser Likely to require additional fertiliser after grazing to ensure maximum grain yield

Weeds Grazing may reduce the incidence of some weeds e.g. wild radish.

Grazing may increase the incidence of some weeds e.g. annual ryegrass. Slows canopy closure may advantage other weeds. Early sowing of cereals to maximise DM may reduce herbicide knockdown effi cacy.

Disease May reduce rust by reducing crop canopy and removing leaves that may cause later infections

Potential exposure to Wheat Streak Mosaic Virus.

Management considerations

Matching stock numbers to feed on offer

If well matched, will enable more stock to be run or supplements to be reduced

If poorly matched, crops may be grazed unevenly or not utilised to their full potential

Economic considerations

Management May allow for a trading operation to be conducted to help diversify

May require ‘boxing’ of mobs to obtain adequate grazing pressure

Fencing May require temporary fencing

Gross margins Increases if the grazing value outweighs silage, hay or grain reductions

Decreases if a reduction in silage, hay or grain outweighs the grazing value

1.5 Grazing crops – making the decision

As you wander around this Grazing Winter Crops Roadshow, you will talk to lots of different people, listen to speakers, read a range of materials, look at trial results. At the end of it all you will probably ask yourself at some stage – so what? What does all this mean? Over the last couple of years, the Grain and Graze project has talked to lots of people about how they make decisions. Some of this research may help you sort out what you have seen and heard during the Roadshow.


Types of Decisions

In business there are three types of decisions – Simple, Complicated and Complex. When you are making decisions about whether or not to introduce grazing cereals into your farming system, you could be faced with all three types of decisions. Here are some examples:

Simple – Are the plants big enough to be grazed? This one should be straightforward, you fi nd out some pretty standard information and the plants are either big enough or they aren’t. You either graze the crop or not.

Complicated – How will I balance crop yield and grazing time? Here there is a few things to consider and you need to balance a few things. For example, what is the grazing worth vs the potential loss in crop yield? Will the crop need more (or less) fertiliser or weed control if it is grazed? To make a confi dent decision you need to get more information, maybe ask an advisor or two and do a few simple sums.

Complex – If I introduce grazing cereals, should I change my farming system to get the most out of the change? To make this decision, you need a lot of technical information on stocking rate, crop growth rates, time of lambing or calving, animal growth rates AND how will changing stocking rate or lambing (calving ) time affect workload, leisure time, seasonal risk, business risk and much more. This decision is COMPLEX.

You could walk away from the day saying “This is all too hard”. Here are a few tips on complex decision making which may help.

Firstly, you are making these decisions all the time and you are probably pretty good at it. You just do it without thinking. Then:

Be clear on your goal. Think about WHY you want to graze crops

Gather information so you feel informed but remember, the decision is complex so you can’t know all the information

Do a few simple sums to get some confi dence it will pay

Discuss the whole story with a range of people you trust. Story telling is very useful for understanding “ins and outs” of complex decisions

Use a couple of advisors to make sure you understand the theory and local experience

Keep it simple – Don’t create more work and make it too complicated

Trust “gut feeling”. At the end of the day, no one can process all the information so you have to trust what your gut tells you

Relax and be prepared to change given what you learn as you go.



1.6 What is on the horizon with grazing crops?

Grazing long vegetative stage wheat crops was a widespread practice in Australia in the 1930’s. While the practice has gone in and out of favour over the decades, the recent interest has been led by farmers wanting to maximise the synergies between their cropping and livestock enterprises.

Increased knowledge over this period has raised some opportunities that could be developed and exploited in the future. These include:

Sowing the same type of crop with different maturity patterns to maximise feed potential and grain yield (see case study 4)

Grazing canola (brassica) crops (see case study 5)

Grazing crops of low palatability by livestock which favour the grazing of weeds (see case study 6)

Training livestock to eat weeds and not the crop (see Training stock to eat weeds and not the crop).

Training stock to eat weeds and not the cropDean Revell from CSIRO, Perth, is researching the grazing behaviour of sheep. His work is suggesting that it may be possible to control the grazing behaviour of sheep so that they eat the weed species targeted by the farmer and avoid grazing the favourable species.

While this work is in its infancy, research undertaken at Utah State University suggests how stock can be trained to be weed managers. The four-step approach involves:

Knowing the nutrient and toxin content of the weeds you want removed

Choosing appropriate animals, that can train unfamiliar livestock

Ensuring animals eat fodder that provides a positive experience, as this will broaden the types of fodder they will eat

Training the stock on small areas that contain the weeds to be controlled.

More information is available on the website: http://www.livestockforlandscapes.com


Case study 4

Exploiting different crop growth patterns to maximise productionThe slow growth of late sown winter wheat posed an interesting challenge for Garry Halliday, Manager of “Poligolet” in South West Victoria. In an attempt to overcome the low winter production, it was decided to mix a shorter season, more rapidly growing spring variety Silverstar with Amarok winter wheat. The maturity difference between the two varieties was approximately two weeks.

It was anticipated that the short season variety would be preferentially grazed by the sheep because of its greater height in winter. The spring wheat would also mature quicker, so theoretically could be removed by hard grazing after stem elongation (growth stage 31+), when the Amarok was still in the tillering phase.

It was unrealistic to expect complete removal of the Silverstar by grazing only, however grazing would delay the maturity of the remaining spring wheat so the ripening would be similar to the Amarok. Given that Amarok is a red feed wheat, the addition of a small quantity of white wheat (Silverstar) to the sample would not compromise grain quality.

The crop was sown dry on April 26 and opening rains occurred in early May. By late July the Silverstar was about 25 cm high and had commenced stem elongation (growth stage 32) while the Amarok was still in mid tillering (growth stage 25) and approximately 10 cm high.

Crossbred ewes and lambs were introduced at a stocking rate of 36 DSE/ha for a period of 38 days until late August. By that time most of the growing tips on the Silverstar had been removed by grazing and the Amarok, which was just beginning stem elongation, had hardly been grazed. The Amarok wheat yielded 5.5 t/ha and the grazing value was calculated at over $200/ha.



Case study 5Grazing canola Work is currently underway to determine the grazing potential of canola. Long season dual-purpose canola has been compared by CSIRO scientists to traditional spring varieties and fodder brassicas. The preliminary results would suggest:

Canola can produce 2 to 4 t/ha of DM for grazing by mid August if sown in mid April

Canola DM has a nutritive value similar to cereals

Sheep show no grazing preference between canola and forage brassicas

Weight gain of merino lambs grazing canola was 210 gm/day, with no observed animal health issues

Both winter and spring canola can recover after grazing with no seed yield penalty if grazing is completed when the plant is in a vegetative stage.

Like cereals, grazing later in the season (early reproductive stage) will delay fl owering and may cause a reduction in seed yield, especially if the season fi nishes early

Oil content was similar between grazed and ungrazed crops.

Case study 6Exploiting grazing preference for weed controlDon Nairn in Western Australia has observed differences in different varieties of oats which he exploits as part of his weed crop control strategy. Don has found Pallingup oats appear unpalatable when green, whereas Tiapan and Grazer 50 grazing oats are readily eaten by stock at the same growth stage.

While more investigation needs to be carried out on the preference of stock to graze certain varieties, it is conceivable that ‘in crop grazing’ could become a standard part of post emergent weed control strategies.



2 What and how to do it (agronomy at the paddock scale)

Dual purpose or winter wheats immediately spring to mind when thinking about grazing a winter crop (see Grazing crops as a drought strategy to minimise seasonal risk in Western Australia). They can be sown early, they remain vegetative until a cold period (which usually occurs in late winter) and they recover from grazing to produce grain. This gives a relatively long period when grazing can occur and still provides options as the crop matures. However, virtually all winter crops can be grazed, even those planted at the traditional sowing times of May and June. It just means the time available for grazing is reduced if grain is also expected. Alternatively, the crop can be grown for the sole purpose of grazing.

If the production of grain is desired, a critical aspect of grazing winter crops is to appreciate the importance of the change in the plant from tillering (vegetative growth) to stem elongation (reproductive growth). This change in plant growth occurs when the part that will produce an ear on the cereal is forming in the base of the plant. Grazing after the plant begins stem elongation risks damaging the ear. For regions where crops are sown purely to provide dry matter (DM) for grazing, there is no need to worry about damaging the embryonic ear of the plant.

Unfortunately, predicting the changes in crop development cannot be determined by a date on the calendar (although crops with a winter habit are more predictable). Visual observation of the emerging embryo ear is the only way to accurately assign this growth stage of a crop.

There is a common referencing system that helps describe the development of a cereal plant from germination through to ripening. It consists of ten (10) development phases from zero to nine (0 to 9). Within each development phase there are up to ten (10) individual growth stages. This gives a two number code and is prefaced with the letters GS for growth stage.

When making decisions about grazing winter crops, the change from GS 2 to GS 3 is critical. GS 2 refers to the development phase when the plant is tillering or producing stems at each crown. GS 3 refers to the development phase when the plant stops tillering and the embryo ear which has formed in the base of each tiller begins to move up the tiller. This phase is also characterised by each tiller beginning to thicken into stems, and nodes forming low down on each tiller. The key growth stage observations to accurately determine a growth stage are described (see table 6 and How to dissect a cereal plant to determine growth stage as well as Hints on how to pick when GS 30 is approaching).


How to dissect a cereal plant to determine growth stage

1 2



For regions where crops are sown purely to provide DM for grazing, there is no need to worry about damaging the embryonic ear of the plant during dissection.

Pull up a plant and shake the dirt off the roots

Pass your hand around the plant and draw upwards to identify the tallest leaf (this will usually be attached to the main stem of the plant)

Peel off any dying leaves

Cut the roots from the plant at the stem base

Cut the stem lengthwise along the stem to expose the embryonic ear.

Want more information? Refer to the Cereal Growth Stages booklet available from the GRDC. It can be ordered from the GRDC website http://www.grdc.com.au in the publications section.

3


Table 6 Description of critical growth stages when grazing winter crops4

Development phase

Code number

Growth stage observationsCode number

Tillering

(vegetative growth)

2 Count the number of tillers excluding the main stem on each plant.

Each tiller is valued at one

1 to 94

Stem elongation

(reproductive growth)

3 The base of the main stem needs to be cut in half and the distance between the base of main stem and the ear measured.

If the ear is at 1 cm, the value is 0

If the ear is at 2 cm, there is a node forming about 1 cm above the base and the stem is hollow, the value is 1

1 to 9

A plant in vegetative growth with a main stem and four tillers would be described as GS 24. The same plant would be described as GS 31 when the ear is about 2 cm above the base of the plant, a hollow is forming beneath the ear and a ring or node is forming about 1 cm above the base of the plant.

To minimise potential grain yield losses, grazing should be completed by GS 30

4 In Australia cereal plants rarely produce nine tillers before stem elongation commences

Hints on how to pick when GS 30 is approaching When a cereal is grazed, it delays the transition from tillering to stem elongation by a few days. Also the main stem of a cereal plant is usually more advanced in its development than the neighbouring tillers.

To gain an indication that GS 30 is approaching, monitor the main stem on plants that have not been grazed. When these plants begin stem elongation, the rest of the grazed crop will not be far behind.

Establishing an exclusion area in a paddock with weldmesh or portable sheep yard panels can provide a point to monitor crop development.



2.1 When to sow

Cereals crops with winter habit can be sown early in the year (March or April) because they need a period of cold weather before they will run to head. This suits areas with a long growing season and usually an early and reliable autumn break.

Crops sown in the early autumn can produce signifi cant amounts of DM before they reach GS 30 if the seasonal conditions are favourable. This applies to the lower rainfall areas (table 7) as well as the higher rainfall zones (table 8).

Table 7 Dry matter available for grazing from barley and wheat sown on April 18, 2007, Waikerie, SA

Crop type Days from sowing

58 86

GS 25 GS 31

Dry matter

(kg/ha)

Dry matter

(kg/ha)

Barley 2080 3490

Wheat 1480 1880

Table 8 Dry matter available for grazing at the end of August for winter wheat sown on May 27, 2004, Marrar, NSW

Variety Dry matter (kg DM/ha)

Wylah 2360

Whistler 2850

Wedgetail 2750

Marombi 2380

Sowing crops dry is possible but relies on adequate rainfall for even germination and further growth. Therefore, don’t sow too early.

If the anticipated break does not occur or there is no follow up to initial rains, the amount of DM at the start of stem elongation (GS 30) may not be much higher than later sowings (table 9).


Table 9 Comparison of dry matter production up to GS 30 for three winter wheats in Tasmania and Southern Victoria (2004 – 2007). The dry matter range is in brackets

Variety Early sowing (some crops dry sown) Traditional sowing date

Average sowing time

Number of trials considered

Dry matter at GS 30

(kg DM/ha)

Average sowing time

Number of trials considered

Dry matter at GS 30

(kg DM/ha)

Amarok Late March 3 1420

(980–2090)

Mid May 6 1230

(730–2020)

MacKellar Mid March 7 1480

(800–2560)

Mid May 7 1000

(590–1730)

Marombi Mid March 4 1310

(960–1830)

Mid May 8 1010

(510–1490)

Cereals sown at the more traditional time (from the start of May onwards) can still produce signifi cant amounts of DM before GS 30 (see section 2.3 for more details).

2.2 What to sow

There is a lot of information available about the choice of winter crops (wheat in particular). Consult your local Agronomist for varieties that suit your local area as they are updated annually. For many farmers winter crops sown specifi cally for grazing may be a relatively small proportion of the total crop sown, if at all.

All cereal crops can be grazed, which provides additional DM for livestock at very little extra cost. Work in the Grain & Graze Program has demonstrated that barley, spring and winter wheat, triticale and oats can all be grazed and can recover successfully afterwards if certain conditions are met. This means the choice of crop and the variety chosen becomes less of an issue, so deciding what to sow should be primarily determined by the existing crop rotation.

The key is to understand the characteristics of the different crops sown, appreciate the amount of DM that can be produced, when this occurs and when GS 30 is reached. This means the grazing opportunities of various crops will be different, especially the cereals with non-winter habit.

While seasonal conditions have a strong infl uence on the amount of DM grown, in general, barley will produce earlier feed than winter or spring wheats when sown at



the same time. The amount of DM that triticale crops produce falls between barley and wheat (see fi gures 2 & 3).

Figure 2 Dry matter production against time of sowing (post May 1) in Western Victoria and Tasmania (2004 – 2007)

Figure 3 Dry matter production (up to GS 30) with a May 16 sowing date, Minnipa, SA (2007)

2,000

2,500

1,500

1,000

500

0

40 50 60 80 100 110

Wheat (winter & spring) Barley

DM

(kg/

ha)

9070

Days from sowing

2,000

2,500

1,500

1,000

500

040 50 60 80 100 110

Barley

DM

(kg/

ha)

9070

Oats Trit

Days from sowing

Wheat


Observations of stock grazing different winter crops suggest a preference to graze some crop types over others. In Victoria, four wheat varieties were always grazed before the triticale, with the two barley varieties being the last to be grazed. However, in Tasmania, livestock that had been grazing wheat and were then offered a selection of wheat, triticale and oats, grazed the wheat last.

While providing choice is unlikely in a farm situation, it is interesting to observe how the grazing preference appears to be associated with the energy value in the various crops at the point of grazing.

Understanding this preference may be exploited in some weed control situations (see section 3.7).

2.3 How much dry matter is produced?

The amount of DM is determined by the climatic conditions, type of crop, sowing rate and use of fertiliser, especially nitrogen. Once established, winter crops have growth rates that exceed pasture growth at the same time.

The regional growth rates of different cereals are provided (appendix 1). Barley has the most rapid growth after sowing, followed by triticale and spring wheat. Winter wheats sown in May or June produce less DM during winter but compensate for this lack of growth in spring. These differences are illustrated (fi gure 4).

Figure 4 Average dry matter production at 60, 90, 120 and 150 days from sowing in Western Victoria (2004 – 2007). Calculated from 38 barley and 50 wheat trials

7,000

8,000

6,000

5,000

4,000

00 60 120 150

DM

(kg/

ha)

90

Days

3,000

2,000

1,000

Wheat Barley



In Victoria, with the varieties chosen, barley reached stem elongation (GS 30 to 31) at an average of 82 days after sowing (range 62 to 91 days) compared to the wheat with an average of 91 days (range 77 to 113 days). GS 32 was reached an average of 16 days later. In contrast, Yrambi barley, which has some winter habit, can be up to 120 days and winter wheats up to 140 days after sowing. These results highlight the variability in timing of crop development and why calendar-based decisions on when to cease grazing are not appropriate.

There are two methods to estimate the amount of DM available in a crop. The fi rst method uses a simple relationship between crop height and DM (see Estimating the amount of dry matter from crop height). A ready reckoner is also provided to convert height to DM (appendix 2). This relationship holds in regions with plant establishment around 200 plants/m2 (sowing rate 80 to 100 kg/ha) and row spacings of between 15 and 20 cm.

In regions where row spacings are wider that 20 cm and plant establishment is more variable, the second method should be used, where crop cuts need to be taken (see Estimating the

amount of dry matter by cutting).

Estimating the amount of dry matter fromcrop heightMeasure the average height of the crop. Then refer to the following relationships (see table).

Table B: Relationship between crop height and available DM (kg/ha) for

crops shorter than 25 cm

Crop Relationship

Wheat Each 1 cm = 60 kg DM/ha

Barley Each 1 cm = 75 kg DM/ha

Triticale Each 1 cm = 65 kg DM/ha

These relationships are based on a 20 cm (8’) row spacing sown at 100 kg/ha. Subtract or add 10 % to the estimate for every 2.5 cm (1’) increase or decrease

in row spacing.


2.4 Options for increasing dry matter production up to growth stage 30

The amount of DM produced before GS 30 can be infl uenced by altering sowing rate and using above average fertiliser (phosphorus and nitrogen) rates early in the life of the crop.

The DM response to increasing sowing rate and fertiliser applies to both high and low rainfall regions (table 10, fi gures 5 & 6). These methods are currently being used by farmers to maximise DM at a critical time of year (see case study 7).

Estimating the amount of dry matter by cuttingThis method relies on access to scales with measurement in grams.

Measure a length of 2 m along the crop row. Cut the selected row to ground level and collect the sample. Repeat a further four times at random locations across the paddock. Combine all cut samples and weigh.

Compare the weight of the sample collected with the table.

Table C: Relationship between collected sample, row spacing and available dry matter (kg/ha)

Weight of green sample collected (gm/10 m row)

Row spacing (cm)

20 25 30

1000 675 540 450

2000 1350 1080 900

3000 2025 1620 1350

4000 2700 2160 1800

These relationships are based on dry matter of 13.5 %.



Table 10 Dry matter produced from different cereal sowing rates and volunteer pasture to September 6, 2005, Karoonda, SA

Treatment Total Dry matter (kg DM/ha)

Single sown cereal 1884

Double sown cereal 2943

Volunteer pasture 1346

Figure 5 Dry matter available for grazing from barley and wheat sown at varying sowing rates (60 kg/ha, 120 kg/ha) on April 18, 2007, Waikerie, SA (with a good early break)

Figure 6 Dry matter available for grazing from barley sown on May 18, 2007 with four different nitrogen applications, Inverleigh, Vic . GS 00 = sowing, GS 22 = 2 tillers

5,000

4,000

58

DM

(kg/

ha)

86Days from sowing

3,000

2,000

1,000

Std fertiliser,double sowing rate

Std fertiliser,std sowing rate

Double fertiliser, double sowing rate

2,000

1,800

100

DM

(kg/

ha)

200

Sowing rate (kg/ha)

1,600

1,400

1,200

45 N @ GS 00 plus 45 N @ GS 22

45 N @ GS 22

45 N @ GS 00

2,200

150

0 N


Increasing sowing rate and application of extra fertiliser comes at a cost. Generally the cost of additional fertiliser is more expensive than increasing sowing rate. To evaluate the benefi ts of increasing DM, a simple calculation can be done where the extra feed produced is valued and the additional costs determined (table 11).

Table 11 Additional cost of increasing sowing rate and fertiliser, Waikerie, SA

Crop Extra DM from control 58 days

after sowing (kg/ha)

Cost($/ha)

Cost per extra tonne of dry matter

($/ha)

Barley sown at 60 kg/ha with 60 kg/ha of fertiliser

0 58 0


160 70 75


570 106 84

In this example the cost of higher seeding rate produced DM that is likely to be cheaper than bought in feed such as hay.

Case study 7

Higher sowing rates to lift winter productionIan Radford from Spalding in mid north of South Australia sowed Wedgetail winter wheat on May 5th into a lupin stubble following 250mm rain earlier in the year. He sowed at 150 kg/ha with 100 kg/ha of 18:20:0, seeding rates well above the district average.

Ian started grazing the crop 46 days later in mid June and grazed until early September with ewes, hoggets and mixed sex cattle. He estimated the crop carried 25 dse/ha from mid June

to early September, when the paddock was closed to grazing. Importantly during the critical feed shortage period from mid June to end July the paddock carried 30 dse/ha.

Growth stage 30 was reached at the end of July, but Ian continued grazing until fi rst heads emerged, and the paddock still yielded 1.6 t/ha of ASW wheat. He would have suffered a yield penalty as the paddock was grazed later than ideal, but Ian was prepared to accept this penalty as a tradeoff for the extra grazing. Nevertheless he achieved a grain return of $600/ha.



2.5 What is the quality of the dry matter?

Winter crops offer high quality feed which is consistently better than pastures at the same time of year. Barley is generally lower in metabolisable energy than wheat or triticale in the vegetative stage. The protein content of all three cereal crops is above the requirements of any class of livestock and the digestible fi bre content is also suffi cient (table 12).

Table 12 Range of dry matter quality of wheat, barley and triticale in the vegetative stage, South West Vic (2004 – 2007) (87 observations)

Crop Energy (MJ ME/kg) Protein (%) Neutral detergent fi bre (NDF) (%)

Wheat 12.4 28.4 38.9

Barley 11.5 27.5 41.7

Triticale 12.2 27.1 41.2

The energy and protein content of the crop changes during the tillering period, increasing up to mid tillering and declining just before and after GS 30 is reached (fi gures 7 and 8).

Figure 7 Change in energy for wheat, barley and triticale during tillering and stem elongation, South West Vic (2004 – 2007) (96 observations)

Met

aboi

sabl

e en

ergy

(MJ/

kg)

9

Wheat

BarleyTriticale

9.5

10

10.5

11

11.5

12

12.5

13

60 70 80 90 100 110 120

Days from sowing

GS 30. Start ofstem elongation


Figure 8 Change in protein for wheat, barley and triticale during tillering and stem elongation, South West Vic (2004 – 2007) (96 observations)

2.6 Grazing

There are several considerations that need to be made when devising a grazing approach.

Deciding when to start grazing is the fi rst consideration. Once the plants are anchored and have grown secondary roots the crops can be grazed. This occurs around the three leaf stage but to be sure a ‘pinch and twist test’ should be applied (see The ‘pinch and twist test’ to determine if a new crop can be grazed).

The ‘pinch and twist test’ to determine if a new crop can be grazed

Pinch the top leaves between the thumb and forefi nger

Pull the leaves upwards while twisting your wrist

If the leaves break off and the plant does not pull out of the ground, the crop can be grazed.

Prot

ein

(%)

10

Wheat

BarleyTriticale

15

20

25

30

60 70 80 90 100 110 120

Days from sowing

GS 30. Start ofstem elongation



Ideally there should be 800 to 1000 kg of DM per ha (1500 kg/ha for cattle) before grazing. However, in reality most crops will not have reached this amount of growth before grazing commences. Postponing grazing until this benchmark is reached will limit the grazing opportunity for those who wish to minimise the impact on subsequent grain yield.

Early grazing will encourage tillering and will keep plants vegetative because it delays stem elongation.

Deciding how much crop to leave behind is contentious and the impact appears to be infl uenced by the length of grazing required and the seasonal conditions after the livestock are removed. Previous recommendations have been to not graze down ‘past the white line’ (see Grazing to the ‘white line’) but this broad recommendation needs to be qualifi ed.

The lower the crop is grazed, the slower it is to recover leaf area. The reduction in growth rate is signifi cant for farmers who wish to graze for an extended period of time. Grazing too low will reduce the crop canopy and its ability to intercept sunlight. This will reduce the growth rate of the crop, which in turn will decrease the amount

Grazing can commence even at low amounts of drymatter.


Grazing to the ‘white line’This refers to the location on the plant where the stems of the tillers change colour from white to green. Allowing stock to eat down into the white part of the stem was considered detrimental to plant recovery but this may not be the case in higher rainfall areas. The ‘white line’

refers to the part where the plant turns from white to green

Heavy grazing. This crop recovered to produce higher grain yield than the ungrazed plots.

of feed available for ongoing grazing. For example in the Northern Ag Region in Western Australia, total DM production was higher after simulated grazing (cutting) down to 10 cm height rather than at 5 cm height (table 13). Grain yield response was also better after being cut at 10 cm than at 5 cm.



Table 13 Total dry matter production of three wheats cut to 5 cm and 10 cm height Badgingarra, WA, 2005

Variety Cutting height (cm) Total DM (kg/ha)

Marombi10 8720

5 7130

Wylah10 9700

5 7200

Wedgetail10 8400

5 6690

Where growth rate is affected, it may require a reduction in stocking rate or removal of stock earlier than anticipated.

In areas of shorter growing season, heavy grazing may limit the amount of time the crop has to recover leaf before the plant produces an ear. At a lower rainfall location on the Eyre Peninsula in 2006 (236 mm annual rainfall), crops that received repeated grazing produced 46 % less total DM (500 kg/ha) than the ungrazed growth (933 kg/ha). The reduction in leaf production corresponded with the crop rapidly running to head particularly under dry conditions.

In contrast, crops in longer growing season areas appear to have time to recover and produce suffi cient DM for successful grain fi ll despite very heavy grazing (assuming spring weather conditions are favourable).

If grazing occurs after GS 30 is reached (stem elongation), then the recommended grazing height must be increased if removal of the embryo ear is to be avoided (refer to start of section 2). The recommendation is to avoid grazing below the node on the stem.


Grazing duration is a third consideration. It is currently recommended that grazing with sheep is completed by GS 30 if the aim is to minimise the risk of grain yield loss (see Hints on how to pick when GS 30 is approaching, page 24 ). For cattle, grazing needs to be completed before GS 32 is reached because they do not graze as low. Grazing can continue after these benchmark growth stages, but a loss of grain yield will occur.

Multiple grazing can be undertaken which gives access to more DM, however, the second and subsequent grazing are likely to occur after GS 30 has occurred. This usually results in a loss of grain yield (table 14).

Table 14 Impact of single and double grazing on grain yield, Edillilie SA, 2006 (summary of 6 wheat and 3 barley varieties)

Crop Grazed early mid tillering, 63 days after sowing (t/ha)

Repeat grazing mid stem elongation, 84 days after sowing (t/ha)

No grazing(t/ha)

Wheat 2.00 1.20 1.92

Barley 2.72 1.81 2.65

Only long season varieties sown early provide an opportunity for multiple grazing.

Trials in the Northern Ag Region of Western Australia found that oats and wheat produced more total DM when grazed (cut) rather than when ungrazed (uncut), with six weekly cuts producing more total DM than four weekly cuttings. Of note was the Graza 50 oats, that yielded 5070 kg/ha when not grazed, 7490 kg/ha when grazed three times (four weekly) and 13,500 kg/ha when grazed twice (six weekly).

The oats also produced higher grain yields when grazed at four weekly intervals than six weekly (however oat grain yields in this trial were very low and the varieties used are more often used for grazing or hay production). Wheat had an increased yield after grazing six weekly rather than four weekly.

Grazing also delays the time a crop will begin stem elongation. This is discussed in more detail later (see section 3.2).

These three considerations (when grazing starts, the amount of crop left behind and the duration of grazing) help calculate the intensity of grazing, or stocking rate.

Where only a small opportunity for grazing exists before GS 30 is reached, very high stocking rates and crash grazing is appropriate. This ensures even grazing of the crop and avoids the ‘lawn and rough’ effect that can occur when stock concentrate grazing on a small area.



If the period of grazing can be increased through early sowing, then the approach to grazing can involve a lower stocking rate for a longer period of time. In this case stocking rate should be matched to crop growth rate, in at attempt to maintain a minimum crop cover of 800 to 1000 kg/ha (see Matching stocking rate to crop growth rate).

If stocking rate is not adequately matched to crop growth, then overgrazing or undergrazing will occur (fi gure 9). This can have implications at harvest as the undergrazed areas will mature more quickly than the heavily grazed areas. In fi gure 9, a stocking rate of 20 lambs per hectare maintained crop cover.

Matching stocking rate to crop growth rate A method to calculate the stocking rate is to estimate the growth rate of the crop and allow 1 kg DM/DSE/day. Estimated growth rates are provided in appendix 1.

For example, a crop growing at 40 kg DM/ha/day could be stocked with the equivalent of 40 DSE/ha and crop growth should match consumption which will maintain crop cover. DSE ratings (appendix 3) and a simple method to calculate an appropriate stocking rate (appendix 4) are provided.

2,000

1,500

14

DM

(kg/

ha)

84

Days of grazing

1,000

500

0

20/ha

10/ha

40/ha

2,500

42

30/ha

28 56 700

3,000

50/ha

Figure 9 Comparison of dry matter of MacKellar wheat with fi ve different lamb stocking rates, Cressy, Tas, 2007


Large paddocks can result in uneven grazing. Stock will concentrate on part of the paddock (top) leaving other parts ungrazed (above).



For many farmers a signifi cant challenge is to fi nd enough stock to graze the crop evenly within the grazing window. This is especially true if the cropping paddocks are large, sowing is late in the season or there are many crops that could be grazed all at the one time. Soil type and the stage of crop maturity will also affect the ability to graze evenly (see case study 8).

Temporary fencing is one way of creating smaller paddocks so that the grazing intensity can be optimised (see case study 9).

“

”

Case study 8

Grazing preference – Rod Batson, Inverleigh, VicRod grazed 1200 young merinos on a 33 ha paddock of Amarok red wheat which was managed in two adjoining paddocks. It was in these paddocks that Rod noticed the fi rst evidence of preferential grazing in any of the cereals.

“Both paddocks had a mix of heavy clay soils and loamy banks,” Rod says.

“From early on it became clear that the sheep were effectively grazing to soil type. They were preferentially grazing the heavier clay soil type bare and left the banks alone.

It happened in both paddocks, the wheat on the clay must have been more palatable.”


“

Case study 9

Temporary fencing to improve the evenness of grazing – Don Nairn, Binnu, WA

In 2003, Don Nairn started grazing a 117 ha paddock of grazing oats with 500 merino ewes. After a few days, he noticed that the sheep didn’t appear to be eating the oats across the whole paddock but concentrating on a particular section. There was also evidence of the sheep camping on top of a hill which was to the detriment of the oats planted there.

To combat this affect, Don used a temporary electric fence to divide the paddock in half.

“The sheep started to graze the oats more evenly, however they still weren’t utilising the feed as well as they could have been,” Don says.

“So the next year I bought more temporary fencing and using a rappa system (a 4WD motorbike fi tted out to unroll temporary fencing), divided the paddock into seven smaller paddocks about 15 ha in size. The smaller areas were then strip grazed.”

Don says the difference was amazing, with the paddocks grazed uniformly and the regrowth was more even. It also prevented the sheep camping in one spot.

”

Temporary sub division fencing (Don Nairn, WA)



2.8 Use of herbicides

Post emergent herbicides are commonly used in crops to control weeds. Most of these herbicides have a withholding period from grazing after application (so do insecticides), so the timing of the grazing and spraying operations need to be considered together. However, grazing may improve the effi ciency of weed control. For example, the use of grazing may enable certain broadleaf weeds to be controlled using a combination of a lower rate of herbicide with grazing (spraygraze technique).

Many herbicides can also have a temporary stunting effect on the plants, which reduces the amount of DM available for grazing. The impact is more pronounced when a greater amount of DM is exposed at the time of spraying (fi gure 10).

Figure 10 Impact on dry matter after the use of Axial post emergent herbicide on wheat (cv MacKellar), Barley (cv Gairdner) and Triticale (cv Monstress), Inverleigh, Vic, 2007

DM

(kg/

ha

0

Mackellar

GairdnerMonstress

1000

2000

3000

4000

5000

6000

60 70 80 90 100 110 120

Days from sowing

2.7 Suitable livestock

Sheep and cattle can graze winter crops. Farmers have successfully grazed lambs, young sheep, pregnant ewes to ewes with lambs at foot. Cattle have also been grazing crops with no reported detrimental effects.

The main issues identifi ed include an occasional increase in scouring and possibly a slight increase in mortality. These are discussed in section 3.6.

Axial applied at 200 mL/ha


A range of common herbicides used in crops post emergence, their withholding periods and effect on crop appearance, as described on the label, is presented (table 15).

Table 15 Common post emergent crop herbicides, withholding periods and label notice of crop injury

Common product name

Active ingredient (s)

Withholding period from grazing

Notes on potential crop injury

Affi nity carfentrazone - ethyl

14 days None noted

Ally metsulfuron - methyl

None if used as directed

Crop yellowing and plant retardation may occur if applied to stressed crop or crop under stress after application

Axial pinoxaden

Cloquintocet - mexyl

21 days Some products can results in crop yellowing or crop injury when applied with crop oils including ADIGOR

Amicide 2,4-D amine 7 days None noted

Diuron diuron None if used as directed

Heavy rain after application may cause severe crop damage

Dual Gold S-metolachlor 8 weeks Damage may occur if crop is sown too shallow (less than 4 cm)

Glean chlorsulfuron Nil, but recommend 24 hrs to optimise weed control

Crop yellowing and plant retardation may occur if applied to stressed crop or crop under stress after application

Gesaprim atrazine Pre emergent application: 15 weeks

Post emergent application: 6 weeks

Use on triazine tolerant canola only.

Hoegrass diclofop - methyl

7 weeks None noted

Hussar iososulfuron-methyl-sodium

None if used as directed

None noted. Use on wheat only

Trifl ur Trifl uralin None if used as directed

None noted

MCPA MCPA 7 days None noted

Midas MCPA, Imazapic, Imazapyr

4 weeks May lead to transient crop yellowing and temporary slowing of growth. For use with CLEARFIELDS wheat only

Roundup

(pre sowing)

glyphosate None if used as directed

None noted

Select clethodim 21 days None noted. Canola only

Sprayseed

(pre sowing)

Paraquat, diquat

1 day None noted

Tigrex MCPA, Difl ufenican

7 days Some transient yellowing may occur.



3 The effects of grazing (impacts at the paddock scale)

There are many potential impacts that should be considered when grazing winter crops. The information presented here seeks to quantify the magnitude of these risks under different situations. With this understanding, each farmer can make a decision on whether to accept the risk and graze the crop.

3.1 Variability in the growing season

Variability in the growing season has a signifi cant infl uence on the impact that grazing can have on grain yield. The accumulation of trial results from many regions indicates that a very severe fi nish to the growing season will cause a reduction in grain yield compared to no grazing, even if grazing has been completed before stem elongation. This is illustrated with results from the Eyre Peninsula where grazing occurred in mid July and only 220 kg/ha of dry matter (DM) was removed from the wheat at grazing and 340 kg/ha from the barley (table 16). The growing season rainfall was less than 50 % of the average at 111 mm.

Table 16 Comparison of grain yield from grazing and no grazing where a severe fi nish to the season occurred, Minnipa, SA, 2006 (summary of 4 wheat and 3 barley varieties)

Crop Crash grazed 65 days after sowing (t/ha)

No grazing

(t/ha)

Wheat 0.59 0.84

Barley 0.53 0.76

In contrast, a favourable fi nish to the season when grazing occurs at late tillering can result in no grain yield reduction (table 17). The reasons for this increase are discussed later.

Table 17 Comparison of grain yield from grazing and no grazing with favourable growing season (growing season rainfall 350 mm), Derrinallum, Vic, 2005

Crop Crash grazed 76 days after sowing (t/ha)

No grazing (t/ha)

Wheat cv Declic 2.8 2.8

Wheat cv Amarok 3.6 3.7

Triticale cv Crackerjack 3.9 3.5

Triticale cv Monstress 3.3 3.2


This information suggests the risk for grain yield is associated with the fi nish to the season. A favourable fi nish greatly reduces the risk to grain yield created by earlier grazing (assuming other aspects such as growth stage are considered). Unfortunately, predicting if the season will fi nish early cannot be done when the decision to graze is made.

Clearly, lower rainfall zones present a greater natural risk by grazing when it comes to the impact on grain yield. However this loss needs to be balanced against the DM obtained for grazing.

Variability of the autumn break will also infl uence the sowing date and potentially the choice of the variety sown. In regions where an early autumn break is more reliable such as the Murrumbidgee and in Tasmania, an early sowing with varieties that have strong winter habit provides a signifi cant window for grazing to occur.

In other regions where the autumn break is usually not until May or June, rapidly growing varieties that do not have strong winter habit should be favoured as they produce DM for grazing more rapidly that winter cereals. However, varieties without winter habit are more unpredictable as to when they may reach growth stage (GS) 30, making ongoing monitoring of the crop critical (see section 2, on Hints on how to pick when GS 30 is approaching on page 24).

Infl uence of season variability

Under favourable growing condition grain yield should not be affected if grazing is completed before GS 30

A premature fi nish to the season is likely to reduce grain yield if the crop has been grazed. This risk is increased in the lower rainfall areas

If sowing early, varieties with strong winter habit should be selected as they maximise the grazing opportunity

If sowing late, varieties with less winter habit should be chosen to maximise rapid growth before GS 30.

in a nutshell



3.2 Effect of grazing on crop maturity

Grazing delays the maturity of a crop. Trial data would indicate the delay to maturity is between three and fourteen days, although this will vary depending on when grazing commences and the duration of grazing. Later grazing delays maturity more so than early grazing (fi gure 11).

Figure 11: Delay in fl owering of barley (cv Gairdner) grazed at different times compared to no grazing, Inverleigh, Vic 2007. Grazing duration 7 days

Grazing will reduce dry matter and delay fl owering (grazed area on right).

0

2

4

6

8

10

12

24 Jul 1 Aug 7 Aug 13 Aug 6 Sep

Date at end of grazing

14

16

GS 30


The same effect is seen with extended periods of grazing, where it appears the time when grazing is completed infl uences fl owering date.

This has both positive and negative implications. If the crop cannot be grazed evenly there will be variability in crop maturity, which may create diffi culties at harvest, especially with barley which is prone to drop grain heads when mature. On the positive side, grazing may be used strategically to delay fl owering that may avoid damage caused by late frosts. Yet it may push maturity into a period of late moisture stress.

Infl uence on crop maturity

Grazing will delay fl owering by between three and fourteen days.

The earlier grazing is completed, the shorter delay to fl owering.

in a nutshell

Uneven grazing will lead to different rates of crop maturity. Three samples taken from an unevenly grazed triticale paddock on 20/07/07. Grazed down to 10 cm (left), grazed down to 15 cm (middle), ungrazed (right) Note position of embryo ear along stem.



3.3 Effect of grazing on grain yield

The impact of grazing on grain yield will depend on two main factors:

the seasonal conditions after grazing

when grazing is completed.

The infl uence of seasonal conditions has been discussed in section 3.1. With unfavourable conditions grain yield will always be affected by grazing. The size of the loss is diffi cult to predict, however the response shown in fi gure 12 illustrates some recorded losses. While the yield reduction appears large, the unfavourable seasonal conditions resulted in grain yields in the ungrazed plots of only 0.81 t/ha (wheat), 0.95t/ha (barley) and 0.6 t/ha (oats).

Figure 12 Grain yield comparison of grazing against no grazing for wheat, barley and oat crops at different growth stages, Minnipa, SA (2005 – 2007)

Gra

in y

ield

aft

er g

razi

ngco

mpa

red

to n

o gr

azin

g (%

)

-60%

-40%

-20%

0%

20%

Growth stage

Wheat

BarleyOats

Early vegetativegrowth

Post emergent(3 leaf )

Late vegetativegrowth

GS 30


In regions with a more favourable growing season, completing grazing at or before GS 30 is critical. Grazing after this point can result in signifi cant grain yield loss, as demonstrated in fi gure 13.

Figure 13 Grain yield comparison of grazing against no grazing for wheat, barley and triticale crops at different growth stages, South West Vic (2004 – 2007)

The positive increase in grain yield has been attributed to less disease, reduced lodging, avoidance of late frost events and possibly the use of moisture at grain fi ll that was conserved earlier in the year because of the reduction in leaf area of the crop.

The suitability of varieties may also help explain the positive benefi ts seen with grazing. In some situations the only varieties available for sowing are not ideally suited to a location and climatic conditions, which means the crop may be more prone to lodging and disease if not grazed, especially if they are sown early.

However even in high rainfall regions, if the crop experiences a period of moisture stress after grazing but before GS 30, it appears to cause signifi cant reduction in grain yield. Observations from a trial in South West Victoria shows a dramatic reduction in grain yield of two long season wheat varieties compared to the ungrazed crop, even though GS 30 had not been reached. Soil moisture probes indicated the crop had

Gra

in y

ield

co

mpa

red

to n

o gr

azin

g (%

)

-60%

-40%

-20%

0%

20%

Growth stage

Wheat

BarleyTriticale

Late vegetativegrowth

Early vegetativegrowth

Stem elongation

GS 3040%

-80%



reached wilting point (no soil moisture available for plant growth) during late August, so despite grazing before GS 30, crop recovery was poor which led to lower grain yield (fi gure 14).

Figure 14 Grain yield comparison of grazing against no grazing for long season wheats (Marombi, MacKellar), indicating period of moisture stress, Inverleigh, Vic, 2007

Grazing after GS combined with moisture stress can result in poor crop recovery and grain yield.

Redu

ctio

n in

gra

in y

ield

due

to g

razi

ng (t

/ha)

-3.0

-2.5

-2.0

-1.5

-1.0

Date at end of grazing

-0.5

-3.5

0

0.5

16/07/07 24/07/07 01/08/07 07/08/07 13/08/07 06/09/07

Marombi

Mackellar

GS 30

Period of moisture stress


3.4 Effect of grazing on grain quality and grain characteristics

There is limited information available on the effect of grazing on grain quality. Early information would suggest grain protein in barley is reduced by grazing, despite signifi cant applications of nitrogen during the growing season (fi gure 15). The effect is not as obvious in wheat and further investigations are required before conclusions can be drawn.

Figure 15 Grain protein comparison of grazing against no grazing for Yerong barley under different nitrogen applications, Inverleigh, Vic 2007. Additional nitrogen applied after GS 30. GS 00 = sowing, GS 22 = 2 tillers

Infl uence of grazing on grain yield

In long growing season areas, the completion of grazing before GS 30 should ensure no grain yield loss unless periods of moisture stress are encountered.

In shorter growing season environments, grain yield losses will occur due to grazing but may be reduced by early grazing.

in a nutshell

Gra

in p

rote

in (%

)

9.5

10

10.5

11

11.5

12

12.5

0 N 45 N@ GS 00

45 N@ GS 22

45 N@ GS 100 plus45 N @ GS 22

Nitrogen treatment

GrazedUngrazed



There is no clear conclusion as to the effect of grazing on screenings and thousand grain weight (grain size). Results are still being analysed at the time of writing but both increases and reductions in these grain characteristics have been measured.

3.5 Effect of grazing on silage, hay and stubble

In most cases grazing will reduce the amount of material left for silage, hay and the stubble after harvest. For silage, there are only limited trial results to examine, although the response of most varieties to grazing is to incur a reduction in DM compared to no grazing (fi gure 16).

Grain quality and characteristics

The impact of grazing on grain quality remains unclear at present except for protein.

Grain protein is reduced by grazing, expecially with barley, irrespective of the levels of nitrogen used on the crop.

in a nutshell

Recovery of triticale for silage after grazing, spectacular but still less than the ungrazed comparison.


Figure 16 Percentage change in dry matter of wheat (green bars) and triticale (light blue bars) when grazing compared to no grazing, Bairnsdale, Vic, 2006

There is no trial data on the effect grazing has on hay production compared to no grazing but it would be fair to assume the response would be similar to silage.

Grazing will also have an effect on the amount of stubble left after grain harvest. Grazing will reduce the amount of stubble remaining, although there is less of an effect the earlier the crop is grazed. This is probably because there is more time for the plants to recover before stem elongation commences (fi gure 17). There may also be a crop type difference, with wheat appearing less affected than barley if grazed early.

DM

com

pare

d to

no

graz

ing

(%)

-40%

-30%

-20%

-10%

0%

10%

Kellalac Marombi Rudd MacKellar

Variety

Amarok Monstress Kosiosko Frelon



Figure 17 Remaining stubble comparison of grazing against no grazing for wheat, barley and triticale crops at different growth stages, South West Vic 2004 - 2007

The reduction in remaining stubble may be useful for farmers who have diffi culty managing high stubble loads. However, for those farmers who can bale and sell the straw, it is important to note that grazing before stem elongation will reduce stubble by up to 30 % even though grain yield may not be affected.

Infl uence of grazing on silage, hay and stubble yield

Grazing will reduce the amount of material available for silage, straw and presumably hay.

This effect can be reduced with early grazing.

in a nutshell

Triticale

Stub

ble

DM

com

pare

d to

no

graz

ing

(%)

-60%

-40%

-20%

0%

20%

Growth stage

Grazed duringlate vegetative growth

Grazed during early vegetative early growth

Grazed duringstem elongation

40%

-80%

WheatBarley

% impact of grazing on stubble mass


3.6 Livestock response to grazing (and animal health issues)

When grazed in the vegetative stage, winter crops are a high quality feed source, with crude protein of 22 to 30 % of DM, metabolisable energy of 11 to 13 Megajoules/kg DM and neutral detergent fi bre of 30 to 40 % (refer to section 2.5 for more details). The plant material has a very high water content of between 80 and 90 %.

3.6.1 Liveweight

The response of livestock to grazing winter crops has been quite variable. A review by Hugh Dove, a Chief Research Scientist with CSIRO Plant Industry, Canberra, found that growth rates varied widely for sheep and cattle.

Low magnesium in the grazing stock has been identifi ed as a likely cause of for the variability in growth rates. Acute magnesium defi ciencies result in grass tetany, however more marginal defi ciencies present themselves as lower than expected growth rates. The cause of the magnesium defi ciency is an imbalance of potassium and sodium in the cereal the animals are grazing. Excess potassium combined with low sodium reduces the absorption of magnesium in the rumen. This defi ciency can be easily rectifi ed with a simple mineral lick (see Recipe for magnesium loose lick).

If no mineral defi ciencies are present and adequate feed is provided, the following growth rates could be anticipated for winter crops (table 18).

Recipe for magnesium loose lick Mix equal parts of Causmag (MgO), ground limestone and salt

Place in containers (drench drum cut in half) and locate in an accessible area for livestock.



Table 18: Anticipated liveweight gains for certain classes of stock

Livestock Liveweight gain (kg/hd/day)

Lambs (25 – 40 kg) 0.25 to 0.30

Hoggets (30 – 35 kg) 0.14 to 0.36

Steers (300 – 400 kg) 1.5 to 1.8

As feed becomes limiting, growth rates will be reduced. This is illustrated in fi gure 18 for a trial where crossbred wether lambs were grazing Mackellar wheat for up to 70 days at fi ve different stocking rates. Once the feed on offer fell below 1000 kg/ha, liveweight gains were reduced. This occurred before the 70 days grazing at high stocking rates.

Figure 18 Liveweight gain of crossbred whether lambs grazing wheat (cv Mackellar) at fi ve different stocking rates, Cressy, Tas. Circles indicate dry mater less than 1000 kg/ha. NB: High initial weight gain probably due to gut fi ll

Live

wei

ght g

ain

(kg/

head

/day

)

-0.1

20/ha10/ha

40/ha

0

0.1

0.2

0.3

0-14 days 14-28 days 28-42 days 42-56 days 56-70 days

Period of grazing

0.4

0.5

0.6

50/ha

30/ha


Farmers have also reported signifi cant weight gains from grazing winter crops (table 19).

Table 19 Liveweight gains recorded by farmers

Producer Location Year Crop Livestock Liveweight gain (gm/hd/day)

Shawcross Ceres, Vic 2007 Barley Crossbred ewes and lambs

337 (ewes), 296 (lambs)

Johnson Warrambeen, Vic

2007 Triticale, wheat

Merino weaners

170

3.6.2 Animal health

Farmers who have started grazing winter crops in the last few years have observed some animal health issues. In interviews conducted with 14 farmers in South West Victoria who were grazing winter crops, 40 % believed there were slightly higher ewe mortalities and 30 % reported increased dags.

Stock grazing lush leafy crops under these conditions will often scour because of the high water content in the plant material. For an animal to eat 1 kg of DM, it needs to eat 5 to 10 kg of green feed. Not all this water can be removed in urine and the excess will be excreted as liquid waste. From an animal health perspective this is not a concern. Scouring may also be caused by a rapid change in diet, where the animal has not become accustomed to the different quality feed.

The simplest way to minimise the potential scouring effect is to provide roughage just before entry to the crop and maintain access to this material during grazing. Late pregnant or lactating cows, or ewes, especially need good quality hay. Additional actions can include introducing stock to the type of feed over a three or four day period or only graze late in the afternoon for the fi rst few days (to avoid potential nitrate poisoning). Always avoid turning hungry stock into a crop on an empty stomach (see case study 10).

Case study 10

Helping stock cope with grazing winter cropsMick Shawcross from Ceres near Geelong, Victoria, has been grazing winter crops for the past six years. Mick tries where possible to introduce ewes and lambs onto cereals gradually so they can adjust to the change in feed. This involves grazing the

stock on an area with volunteer cereals in pasture prior to putting the stock on the cereal or allowing access to a pasture paddock during the introduction period. Hay is also used. He fi nds the stock don’t get daggy on the cereals because they have access to hay and have an introduction period with cereals to help them adapt.



Canola can pose a greater risk to animal health than cereals, but this usually occurs when animals are suddenly introduced to the crop, often combined with conditions that make the crop stressed such as a lack of moisture, frost or herbicide application. The potential animal health problems include pneumonia, gastroenteritis, liver damage, photosensitisation and nitrate poisoning. Stock should be fully vaccinated against enterotoxaemia before grazing. The recommendation when grazing canola is to offer hay and observe the animals closely for at least the fi rst two weeks of grazing.

Recent use of nitrogen fertiliser on cereals and brassicas can also increase the risk to the livestock, as can crops growing on very fertile soil. The risk of nitrate poisoning is higher during dull, cloudy weather due to reduced photosynthesis in the plant. As a precaution, it is recommended not to graze for three weeks after a nitrogen application.

3.7 Grazing and the impact on crop weeds

Some farmers have raised concerns that grazing may increase the weed density in crops by removing competition, encouraging germination of weed seed or increasing tillering once the weeds are grazed.

While there is very little information regarding the effect grazing has on weed status within crops (especially cereals), some basic principles about weeds in crops are well established:

Increased crop competition will reduce weeds. This can be achieved through:

Livestock issues

Livestock have potential to achieve high growth rates grazing cereals

Farmers have observed slight increases in mortalities and dags when grazing cereals

Hay can be used to help reduce scouring and digestive upsets when stock are introduced to lush cereals

Cereals are usually low in sodium and sometimes magnesium, so a mineral lick should be offered (see Recipe for magnesium loose lick on page 56)

Stock grazing canola crops can be exposed to additional animal health issues and extra care is needed; especially in the fi rst two weeks

Do not graze crops for three weeks after applying nitrogen fertiliser.

in a nutshell

“

”

Case study 12

Grazing preference – Don Nairn, Binnu, VicFor the past three years Don Nairn has been strip grazing Pallinup oats with merino ewes as a form of weed control on wild radish. He then crops his paddock the following year for grain.

Don says, “the sheep preferentially graze the radish as they don’t seem to like the taste of the Pallinup oats. The radish will re-shoot but the sheep just keep selecting it. This prevents the radish reaching the fl owering stage and any plants that do survive are smaller and are much easier to control if I do decide to spray. As herbicide resistance to wild radish is becoming more of a problem, grazing can be used to minimise the use of herbicides.”

Strip grazing Pallinup oats to remove wild raddish. Ungrazed on the left.

Page 60


Variety selection. The most competitive –crop types are oats, followed by barley, then wheat and fi nally triticale

Higher sowing rates and narrow row –spacing have been shown to dramatically reduce annual ryegrass seed heads. A minimum plant density of 200 plants/m2 is suggested to maximise competition while minimise any potential grain yield reduction

Time of sowing, with earlier sowing –generally favouring more vigorous cereal plants and therefore providing greater competition to the weeds

Adequate fertility and soil conditions are –essential to maximise the competitive growth rate advantage cereals have over many weeds.

The amount of weed in a crop directly infl uences subsequent weed seed production. Reducing the amount of weed in a crop will reduce weed seed set.

3.7.1 So what does this mean for grazing crops?

The basic principles of weed control in crops are complementary to the practices used in grazing winter crops. Maximizing leaf production through high plant density, adequate soil fertility and selection for rapid growing crops all suit weed control strategies and DM production for grazing. However there are some specifi c issues related to grazing that need to be considered.

Grazing preference

Livestock often show a grazing preference for some plants over others. This occurs in cereal crops and with weeds in a crop. A trial in South West Victoria comprising two barley, one triticale and four wheat varieties grazed at six different times, demonstrated sheep had a clear preference for the wheat varieties over the barley varieties.

Observations of this preference difference have been used successfully by Don Nairn in the Northern Ag Region of Western Australia. Sheep have been used to selectively target radish in both lupins and Pallinup oats with great success (see case study 12).



Grazing intensity

There has been limited work examining the effect grazing intensity has on long term weed populations. Observations and measurements taken during the Grain & Graze Program can help in understanding some of the interactions that might be occurring.

The fi rst is the ability of grazing to reduce the amount of weeds and therefore reduce the weed seed set. Measurements in South West Victoria showed that grazing reduced weed mass (mainly annual ryegrass) by 34 % in triticale when measured at GS 60 (fl owering). No seeding data was collected as the crop was cut for silage.

Secondly, it has been observed that if both weeds and cereals are intensively grazed to the same level early in the growth of the crop, the actively growing cereal re-grows more rapidly than most weeds thereby putting the weeds at a disadvantage. Lax grazing where only the top part of the canopy is removed has a tendency to reduce shading of the weeds by the cereal, thereby allowing the weed to intercept more sunlight.

Finally, grazing may encourage the late germination of some weeds. Measurements on six grazed and ungrazed crops in South West Victoria suggested a slight increase in annual ryegrass (lolium rigidum) populations when the crop was grazed at late tillering (fi gure 19). For other opportunistic weeds such as toadrush (Juncus bufonius) which germinates when soil becomes saturated and lose structure, grazing during wet conditions can lead to signifi cant increases in populations (fi gure 20). Yet for other weeds, grazing may be benefi cial as appears to be the case with paradoxa grass or annual phalaris (phalaris paradoxa) (fi gure 21).

Figure 19 Impact of grazing on annual ryegrass population, South West Vic, 2007

Popu

latio

n (p

lant

s/m

2 )

0

10

20

30

40

50

Mt Moriac(1)

Grazed Ungrazed

Mt Moriac(2)

Mt Moriac(3)

Inverleigh Mininera(1)

Mininera(2)


Figure 20 Impact of grazing on Toadrush population, South West Vic, 2007

Figure 21 Impact of grazing on Paradoxa grass population, South West Vic, 2007

Popu

latio

n (p

lant

s/m

2 )

0

20

40

60

80

100

Grazed Ungrazed

Mt Moriac(3)

Mininera(1)

Mininera(2)

120

140

Popu

latio

n (p

lant

s/m

2 )

0

20

40

60

Grazed Ungrazed

Mt Moriac(2)

Inverleigh



In Tasmania, the density of annual ryegrass plants was fi ve to six times lower in undergrazed plots with 10 lambs/ha compared with 20 lambs/ha (optimal stocking rate) and higher rates (30, 40 and 50 lambs/ha) (table 20). Visual observations indicate the extra leaf in the crop grazed with 10 lambs/ha would have shaded the ryegrass, potentially reducing germination and vigour. In nil-grazed exclusion areas the density of ryegrass was comparable with the lowest stocking rate.

Grain yields also refl ect the possible effect that different ryegrass densities may have (table 20). Grain yield from the lowest stocking rate out-yielded the other stocking rates by an average of 15 %. Some of the grain yield reduction from heavier grazing may be due to direct effects of grazing but the data shows the importance of adequate weed control when grazing.

Table 20 Effect of grazing intensity on density of ryegrass plants and grain yield of Mackellar wheat, Cressy, Tas, 2007

Stocking rate (lambs/ha) Ryegrass (plants/m2) Grain yield (t/ha)

10 3 6.30

20 17 5.08

30, 40, 50 (average) 21 5.44

Understanding the weed response to grazing is complex and the information available to date prevents recommendations being made with any confi dence. While there are examples of sheep actively seeking out some weeds in a cereal crop, it is unlikely that this can be assumed over a range of crops, population of weeds, varieties and growth stages. Also the variability in the response of different weeds to grazing adds to the confusion.

The current recommendation would be to avoid grazing crops that currently have or are known to have had a history of weed problems.

Weed issues

Maximise crop competition through consideration of time sowing, variety, sowing rate, row spacing and higher rates of fertiliser

Graze early and graze hard

Do no graze crops that contain high weed populations or have a history of weed problems (unless the grazing benefi ts on weed control have been established).

in a nutshell


3.8 Grazing and the impact on crop diseases

The emerging threat of Wheat Streak Mosaic Virus (WSMV) poses a potential challenge to early sown cereal crops (see What is Wheat Streak Mosaic Virus?). The ability to achieve the required break in the ‘green bridge’ may reduce the opportunity to sow crops early.

The anecdotal information on diseases in cereal crops is quite variable. Some farmers believe grazing has reduced disease such as rust by removing the diseased leaves and therefore the source of ongoing infection, or by reducing the canopy which improves air circulation and creates a less favourable condition for disease build up.

What is Wheat Streak Mosaic Virus? Wheat Streak Mosaic Virus (WSMV) is spread by the wheat curl mite and affects wheat, barley and oats as well as other crops and grasses. The virus affects the leaves of the plant and can result in signifi cant yield losses, especially to early sown crops. In 2005, WSMV caused the failure of 5,000 ha of crop in NSW and a further 20,000 ha in 2006.

The mite survives from season to season by living on green plant material such as volunteer cereals and grasses in crops as well as along the paddock boundaries. If this ‘green bridge’ is broken, the mites will not survive.

The current recommendation is to remove all green material for two to four weeks before sowing the crop.

Example of grazing reducing disease incidence in crop (ungrazed on left, grazed crop on right).



Observations of stripe and leaf rust in two barley and four wheat varieties in South West Victoria revealed no signifi cant difference in rust incidence in the grazed and ungrazed plots (table 21). However the observations were taken during a drought year where the rust incidence was extremely low.

Table 21 Level of leaf rust incidence (%) in two barley and four wheat varieties – Inverleigh Vic, 2006 (colour indicates most important leaf contributing to grain fi ll)

Crop Flag leaf Flag leaf - 1 Flag leaf - 2

Grazed

(%)

Ungrazed

(%)

Grazed

(%)

Ungrazed

(%)

Grazed

(%)

Ungrazed

(%)

Wheat 0.1 0.4 1.5 1.6 2.4 3.3

Barley 0.3 0.1 2.1 1.5 2.5 2.8

Opposing observations have also been reported, especially in crops that are sown early.

Crop disease issues

Wheat Streak Mosaic Virus has the potential to severely affect early sown cereal crops

There is no strong evidence of the effect grazing has on other common disease such as rust.

in a nutshell


Appendix 1Average cereal growth rates by Grain & Graze region

NB: These are average fi gures only and are highly dependent on adequate growth conditions

Corangamite / Glenelg Hopkins (Southern Victoria / Tasmania)

Crop scenario: Winter wheat (March sown, good break or irrigated)56

Month Growth rate (kg DM/ha/day) Grazing

Mar 5Apr 15May 25 Possible1

Jun 30 YesJul 60 YesAug Possible2 Sep

Crop scenario: Wheat (May sown)


May 5Jun 15Jul 25 Possible1

Aug 40 YesSep Possible3

Crop scenario: Barley (May sown)


May 15Jun 25 Possible1

Jul 35 YesAug 100 YesSep Possible2

Growth rates for May sown triticale are between wheat and barley.

1 Grazing could start if plants are well anchored 2 May get grain yield loss if grazing past early September3 May get grain yield loss if grazing past mid September



Eyre Peninsula (South Australia)

Crop scenario: Wheat (May sown). Lower North SA


MayJun 10 Possible1

Jul 20 YesAugSep

Northern Ag Region (Badgingarra) WA

Crop Scenario: Winter Wheat (May sown)



Jul 25 YesAug 40 YesSep

Crop Scenario: Wheat (May sown)




Crop Scenario: Barley (May sown)




Crop Scenario: Triticale (May sown)





Appendix 2 Ready reckoner of crop height and estimated dry matter

Crop height (cm)

Crop type

Wheat (kg DM/ha) Barley (kg DM/ha) Triticale (kg DM/ha)

1 60 75 65

2 120 150 130

3 180 225 195

4 240 300 260

5 300 375 325

6 360 450 390

7 420 525 455

8 480 600 520

9 540 675 585

10 600 750 650

11 660 825 715

12 720 900 780

13 780 975 845

14 840 1050 910

15 900 1125 975

16 960 1200 1040

17 1020 1275 1105

18 1080 1350 1170

19 1140 1425 1235

20 1200 1500 1300

21 1260 1575 1365

22 1320 1650 1430

23 1380 1725 1495

24 1440 1800 1560

25 1500 1875 1625



Appendix 3Dry sheet equivalent (DSE) rating for different classes of livestock

Sheep

Class of livestock Bodyweight (kg)

40 50 60 70 80

Dry sheep 0.9 1.1 1.2 1.3 1.4

Pregnant ewes, last month

- singles 1.2 1.4 1.6 1.8 2.0

- twins 1.4 1.6 1.9 2.2 2.5

Lactating ewes

- singles (100%) 2.6 2.7 2.9 3.1 3.3

- twins (200%) 3.7 3.9 4.4 4.9 5.4

Weaned lambs

- Merino 20 kg 0.6 – 1.0 depending on desired rate of liveweight gain

- X bred 30 -40 kg 1.0 – 1.5 depending on desired rate of liveweight gain

Source: Prograze

Cattle

Class of livestock Bodyweight (kg)

500 550 600

Pregnant, last 3 months 11 12 13

Lactating cow & calf, 0 – 3 months 13 14 15

Lactating cow and 150 kg calf 18 19 20

Steers 200 300 400

Rate of gain

- Maintenance 4 6 7

- 0.5 kg/day 6 7 8

- 1.0 kg/day 8.5 11 13

Source: Prograze


Appendix 4Budget sheet to calculate the number of stock needed to graze a specifi ed herbage mass over a given number of days

*1 The amount of crop DM at the start (appendix 2) minus the amount of crop you want to leave behind (refer to page 35)*2 The estimated daily crop growth rate for the paddock during the budget period (appendix 1)*3 The available crop plus the amount grown over the budget period. Column A plus (column B multiplied by column C)*4 The total DM divided by the number of days. Column D divided by column C*5 The amount of crop the average animal in the herd or fl ock will eat per day (refer to page 39 and appendix 3)*6 The pasture allowance per day divided by the amount each animal eats. Column E divided by column F.

Source: Modifi ed table from Prograze

Date Paddock AAvailable DM (kg DM/ha)*1

BCereal growth rate(kg DM/ha/day)*2

CDays in the rotation



DTotal DM over the budget period (kg DM/ha)*3

ECrop available/day(kg DM/ha)*4

FCrop allowance/head/day (kg DM)*5

GStocking rate required (no of head)*6

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