fertiliser management plan for mr victor rodwell, boyanup...

Nutrient Management Systems for the Dairy Industry and Intensive Agriculture in the South West

Fertiliser Management Plan

For

Mr Victor Rodwell, Boyanup WA.

Prepared by

Sam Taylor

On behalf of Western Dairy Inc.

Nutrient Management Systems for Dairy Farms Project [1]

Background to project

In February 2008, the WA Dairying for Tomorrow Coordinator developed a project in partnership

with Dr. Daniel Murphy from the University of WA. The project was to engage relevant ‘ Nutrient

Management stakeholders in South West of Western Australia with an outcome to develop whole

farm nutrient plans, which would both support producers to implement improved nutrient

management on farms and address growing accountability concerns form relevant management

agencies. A systematic approach would be adopted, creating a standard for farm nutrient

management plans.

During October 2008 a planning meeting was held to start off the project and implement the project

team. Farm interviews were carried out in December 2008 and soil testing commenced in January

2009, with completion in February 2009. Up to 40 paddocks (sites) were sampled on the milking

platform (home farm for beef growers) of the properties for comprehensive nutrient analysis. Data

from these results was considered in conjunction with farm management details collected during the

survey process, and farm nutrient management plans have been identified.


Farm Statistics & Nutrient Summary

Farmer Victor Rodwell, Rodwell Farms

Farm Size (Milking Platform / Home Farm) 411

Arable ha 371

Arable % 90%

Production

Dairy Volume 5,300,000 Litres

Fat 3.82% %

Protein 3.20% %

Rainfall 1000 mm

Report Period Begin Date 1/01/2008

End Date 31/12/2008

Summary of total farm nutrient inputs and outputs

Nutrient Balance Summary Victor Rodwell, Rodwell Farms

kg’s of nutrients N P K S

Inputs 88218 16985 32178 16921

Outputs 36339 6539 7834 2323

Surplus / Deficit 51879 10446 24344 14598

Surplus / Deficit (Arable HA) 140 28 66 39

Fertiliser use efficiency (Total Removed in Produce / Total Input)

N P K S

Efficiency 41% 38% 24% 13%


General Farm Details

A modern dairy business aptly describes the farming enterprise of Victor Rodwell. Irrigated

pastures, dryland production and run off blocks along with modern harvesting equipment see this

600+ cow dairy striving for maximum production. Annual production of milk exceeds 5 million litres.

Other lease property and run off blocks complement the dairy platform for the production of fodder

and accommodation of young and dry stock.

Irrigated pastures have been intensively fertilised (and monitored) on a rotational basis, and

subsequent soil and plant tissue testing has been incorporated into the management regime. Soil

samples have been GPS located on transects within designated paddocks to monitor trends of

nutrient status and plant tests are taken up to 4 times per annum. Fertiliser has been applied by

contractors with GPS and weighing equipment on their machinery and own machinery that is

calibrated on farm.

Rotational grazing is employed with fertiliser applications made post grazing. Leaf stage is targeted

at 2.5 – 3 leaves, with pasture growth rates monitored by District Average Pasture Growth Rate

numbers (Pastures from Space data), mean temperatures and continual paddock assessment.

Due to the intensive nature of monitoring on the milking platform, management is moving away

from complete (N, P, K, S) blends to more specific nutrient applications where required. The fact

that data is available on every paddock from soil and plant tests allows this management shift to

occur.


Farm Inputs and Outputs

During the report period (1/1 to 31/12 2008) the following nutrient was imported to the farm:

Product Description Tonnes kg Nitrogen kg Phosphorus

Fertiliser NPKS Blend 200 50600 7800

Fertiliser Super Potash 5:1 28 0 2128

Fertiliser Chicken Manure 70 12150 2510

Stock Feed Cereal Grains 800 14520 2234

Stock Feed Lead / Calf Pellets 45 1038 119

Stock Feed Canola Meal Pellets 150 870 144

Stock Feed Pasture Silage 78 3120 312

Stock Feed Pasture Hay 170 4250 425

Stock Feed Cereal Straw 33 594 50

Livestock Returning Heifers 28 913 224

Livestock Bulls 5 163 40

Total 88218 15986

The export of nutrient from the property is confined to the sale of Stud Bulls, Cull Bulls, Mature

Cows and Heifers. This results in the following nutrient export from the property.

Product Description Litres/ kg

Liveweight

kg Nitrogen kg Phosphorus

Milk Milk 5,300,000 30210 5035

Cattle Liveweight Calves 105,000 3423 840

Cattle Liveweight Cows 78,000 2543 624

Cattle Liveweight Bulls 5,000 163 40

Total 36339 6539

Nutrient Surplus / Deficit

From the above tables of imports and exports, nutrient surplus and/or deficit can be identified. This

is calculated on a basis of total kg nutrient and kg nutrient per arable hectare. A subsequent

efficiency of nutrient use is also calculated by dividing nutrient outputs by the nutrient input.

kg’s of nutrients N P

Inputs 88218 16985

Outputs 36339 6539

Surplus / Deficit 51879 10446

Surplus / Deficit (Arable HA) 140 28

Efficiency % 41% 38%


Nutrient Surplus / Deficit Discussion

As identified in the previous table, a nutrient surplus is occurring on this property, although only

small in terms of kg/ha of nutrient. Farm Gate Nutrient Balance Survey work carried out between

2002 to 2008 in 7 catchments in the South West of WA (Weaver et al 2008) over 400 properties

shows the following statistics for beef and dairy nitrogen and phosphorus surplus and efficiency.

These averages are also compared to your results in the following table.

Phosphorus and Nitrogen Surplus (kg N/ha) and Efficiencies (%)

Survey Average Your Result Survey Average Your Result

N Surplus N Efficiency N Surplus N Efficiency P Surplus P Efficiency P Surplus P Efficiency

Beef 75 9% 8 19%

Dairy 128 19% 140 41% 17 28% 28 38

In the case of nitrogen, your surplus (kg/ha) is marginally above that of other dairy properties

surveyed. Efficiency of Nitrogen use however is well above the average, indicating that on farm

nitrogen use is tactical and results in high levels of production from the application of Nitrogen.

Across a wider range of extensive industries (Beef, Dairy, Cropping and Mixed Farming), Nitrogen

surplus average is 67 kg/ha and Nitrogen Use Efficiency is 32%. This high surplus is driven by cattle

for both beef and dairy and mixed grazing, which includes sheep. The increased level of efficiency

on average for the group of mixed farming practices over the average efficiencies for beef and dairy

is created by the very high efficiencies achieved in cropping industries.

Phosphorus surplus (kg/ha) on your property is also above the average, however as a result of good

on farm productivity, Phosphorus use efficiency is above industry standard for beef production. The

average Phosphorus surplus is 9.1 kg/ha for the combined extensive industries of Beef, Dairy,

Cropping and Mixed Farming and the Phosphorus Use Efficiency is 32%. Cropping industries again

highlight their efficiency in nutrient use by having lower surpluses and higher efficiency ratings than

grazing enterprises.

These higher than average surpluses and higher than average efficiencies may seem unusual, and I

suggest that it is a fact that your business has significantly more scale than the average of the survey

population.


Soil Test Data Results, Analysis & Recommendations

Comprehensive soil analysis has been carried out and the following parameters were analysed:

pH, Electrical Conductivity, Organic Carbon, Nitrogen (Nitrate & Ammonium), Phosphorus (P),

Phosphorus Buffering Index (PBI), Potassium (K), Sulfur (S), Trace Elements (Copper (Cu), Zinc (Zn),

Boron (Bo), Manganese (Mn) and Iron (Fe)) Aluminium (Al), Chloride (Cl) and the Exchangeable

Cations (Calcium (Ca), Magnesium (Mg), Potassium, Sodium (Na) & Aluminium). These extracts also

help to determine the Exchangeable Magnesium and Sodium percentages and the Calcium :

Magnesium ratio and the Effective Cation Exchange Capacity (ECEC).

Critical Limits (pH, P, PBI)

When interpreting soil test data, it is useful to understand the critical soil concentration limits of

particular analytes to determine if the soil will be responsive or not to applications of nutrient or a

management factor. For the purposes of this project, the most useful analytes to determine soil

response are the soil pH and the Phosphorus concentration in conjunction with the Phosphorus

Buffering Index (PBI).

As acidity is a major limitation in Western Australian farming soils, it is seen as important to manage

the pH of the soil and to target a soil surface (0-10cm depth) pH of 5.5 (the target pH) measured in

Calcium Chloride (CaCl). Measurement of soil pH in CaCl is the national standard. Achieving a soil

surface pH of 5.5 will generally see nutrients stored in the soil at their most available level in the soil

solution, aluminium locked into the soil solution and no longer an impediment to root growth, and

the effects of subsoil acidity (10-20cm and deeper) declining.

No one set value can be used as a critical value for phosphorus (P) across all soil types. As the

Phosphorus Buffering Capacity (PBI) of a soil changes, so does the critical value at which no further

response will be seen to increasing rates of P. PBI is the recognised national standard for

determining a soils capacity to fix (tie up) phosphorus. As the paddocks tested were rated for their P

status a matrix of high, medium and low P levels was required. This rating was then transferred to

the farm map showing P status in paddocks on the property. The following table outlines the critical

values used to determine the P status of paddocks sampled.

Phosphorus Fixing Status Soil P Level (mg/kg)

Phosphorus Fixing Level Phosphorus Buffering Index Low Medium High

Very Low 3 - 10 < 7 7-10 10+

Low 10 – 20 < 15 15-20 20+

Moderate 20 – 40 < 20 20-25 30+

High 40 – 60 < 25 25-35 40+

Very High 60 – 150 < 30 30-45 50+


Critical Limits (Other Nutrients)

No set values have been used for Nitrogen. As the nitrogen figure for any paddock varies

significantly during the growing season, the nitrogen figure is used to determine the N status at the

beginning of the season and to plan which paddocks may be the most responsive to nitrogen

applications (where required). This N status is also considered in conjunction with the soils Organic

Matter (OM) percentage, as this influences the soils ability to provide nitrogen in the organic form.

Potassium values of 100 mg/kg have often been used in the South West as a critical limit. More

recent research and changes in pasture composition have seen these critical values questioned and

they are now not so clearly defined. For the purposes of determining specific recommendations in

relation to potassium, ranges have been identified to which various management practices have

been advised.

Potassium Level Management Advised for general pasture

< 60 mg/kg Low Autumn (10-20 kg K/ha) and High Spring (20-30 kg K/ha) applications

60 – 100 mg/kg Plant test during winter and Spring (20-30 kg K/ha) application

>100 mg/kg Plant test during winter, K on hay/silage paddocks only

Sulfur (S) is highly leachable in the sulphate form and many commonly used fertilisers contain sulfur

in this form. 10 mg/kg is considered to be an adequate soil S level.

Where identified as low, trace elements, copper and zinc in particular, have been addressed

specifically on a paddock by paddock basis to remedy soil levels or implement management to

monitor levels and determine any impact on pasture production.

Exchangeable Cations

The measurement of exchangeable cations are useful in determining the soils ability to hold onto

and give up nutrient through the Effective Cation Exchange Capacity (ECEC) and the presence of any

major soil structural problems through the exchangeable sodium and magnesium percentages.

Where they are highlighted as potentially an issue, further discussion surrounding the specific soil

type in the paddock is warranted and management options evaluated.


Specific Recommendations for Fertiliser

Data from the soil analysis was analysed on the basis of the critical limits previously discussed.

Lime – Paddocks were analysed on the basis of pH (CaCl) and also Aluminium content. From this

analysis, paddocks were placed into 1 of 3 management categories as outlined in the table below.

Discussion regarding the implementation of a liming program and the correct technique of

evaluating a lime source was also held.

No Lime 1500 kg/ha 2500 kg/ha

7 27 2 19 42 1

8 32 4 21 43 3

9 36 5 25 44 17

13 37 6 29 45 28

14 38 10 30 46

20 39 11 31 47

22 40 12 33 48

23 15 34 52 No Data

24 16 35 49

26 18 41 50

51

Phosphorus – Based on critical soil levels presented, paddocks were split into management zones for

either a Low (4.5 kg P/ha), Medium (9 kg P/ha) or High (18 kg P/ha) phosphorus application.

5 kg P/ha 15 kg P/ha 30 kg P /ha

1 20 34 5 36 12

2 21 38 6 37

3 22 39 10 44

4 23 40 11 46

7 24 41 13 52

8 25 42 15

9 26 43 16

14 27 45 30 No Data

17 28 47 31 49

18 29 48 32 50

19 33 35 51


Potassium – Paddocks identified based on soil test levels of K. 3 management practices advised

depending on the K status of the paddock.

<60 mg/kg K – 10-20 K Autumn, 20-

30 K Spring

60-100 mg/kg K, plant test

winter and apply 20-30 K spring

>100 mg/kg K, no K

except on Hay Paddocks

4 18 26 1 33 2 46

9 19 27 3 36 5 47

10 20 28 6 38 30 48

11 21 34 7 40 31 52

13 22 35 8 43 32 No Data

15 23 37 12 39 49

16 24 41 14 44 50

17 25 42 29 45 51

Following these recommendations, growers will face a change from blanket applications to site

specific applications. As they now have the data on a paddock by basis due to intensive soil testing,

these areas are easily identified. The complication now becomes the logistics of managing the

application of different fertiliser types and rates to different paddocks. In some cases this may

require a second application to a paddock with a different fertiliser (eg 1 application of phosphate

and second application of potassium) as it may now be more feasible to apply these separately as a

single blended product is not required over the whole property. Previously employed blanket

application techniques generally result in areas of a property under and over fertilised as no one

fertiliser can fit the requirements of varying soil types across landscapes.


Spreadsheet Table of Complete Data Set for Extensive Nutrient Analysis

Rodwell Farms

Spreadsheet also supplied to grower containing data and recommendations based on critical limits.


Farm Maps

Nutrient Management Zone maps have been created that identify areas of low, medium and high fertility. These maps visually highlight the varying levels of fertility

between paddocks, and that it is prudent to consider treating areas of the property differently when it comes to nutrient applications.


NMS Spreadsheet Tool

A simple Microsoft Excel based spreadsheet tool has been developed to help growers through the

process of calculating their own on farm nutrient surplus / deficit on farm. Entering basic details on

farm production and selecting products imported and exported from the property from drop down

lists along with their quantities sees calculations performed quickly. This will help the grower to

identify where they may have short comings within their current system and to calculate their actual

nutrient efficiencies.


Recommendations & Summary

From the interpretation of soil test data, it can be seen that there is significant scope to change

management practices in relation to on farm nutrient applications.

Intensive Testing Soil Testing Regime: The value of intensive soil testing is proving to be extremely

worthwhile, and this will further prove itself in time as continued testing defines paddock trends in

relation to nutrient levels and soil physical properties. More stringent analysis of management

techniques and applications will be possible, growers will gain a better understanding of the fertiliser

decisions they are making and this will ultimately lead to improved pasture productivity as fertiliser

is applied where it is required at the most appropriate rate, rather than a blanket application across

a paddock or property as it was the “best fit” for soil types and production requirements.

Continued testing of all paddocks is advised to aid grower’s future nutrient management decisions.

As several growers have said during the course of the project, “I only have to save a few tonnes of

fertiliser to cover the cost of the sampling.” Soil sampling should be carried out every 3-4 years.

Paddock Specific Applications: Now that growers have soil test data for every paddock, they can

clearly see that there are large differences in soil characteristics and nutrient levels and

requirements between paddocks. As a result of this, an apparent change is required in treating land

management units separately, as this will improve nutrient availability at critical times during the

season and prevent under, and more importantly, over fertilising from occurring. It is the over

fertilising of nutrients such as Phosphorous and Nitrogen that represent the greatest environmental

dangers and have the largest off site impact. By changing to paddock specific applications, growers

can work with the physical characteristics of the paddock (ie PBI and nutrient levels) to ensure that

enough fertiliser is applied to reach production targets, whilst being aware of any potential

inefficiencies and potential off site impacts.

Moving away from blanket application rates across properties, to paddock specific applications of

key nutrients such as Nitrogen, Phosphorus & Potassium is recommended.

Summary

Land managers will undoubtedly come under increased scrutiny regarding the use of bulk fertiliser in

future years, particularly in those areas deemed to more environmentally sensitive. Combined with

the inevitable “cost price squeeze” of extensive farming such as dairy and beef production, it makes

sense that growers only apply fertiliser where pasture production responses will be seen and at

rates which are economically sustainable. Adopting a nutrient management regime following the

strategies advised above will ensure that growers are responsible in their use of bulk fertiliser, whilst

making the most economically sustainable decisions for the long term prosperity of their business.

fertiliser management plan for mr victor rodwell, boyanup...

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