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Estimating Soil Phosphorus Budgets
For
Rural Municipalities in Manitoba
by Petra Loro, Mehdi Arzandeh, Derek Brewin,
Wolé Akinremi, Collin Gyles and Dupe Ige
May 30, 2013
1
Table of Contents
EXECUTIVE SUMMARY ....................................................................................................................... 1
BACKGROUND ........................................................................................................................................ 2 NUTRIENT USE IN CROP PRODUCTION ........................................................................................................ 2 SOIL P BUDGETS .................................................................................................................................................. 3 MANAGEMENT OPTIONS TO IMPROVE P BALANCE .................................................................................. 4
Feed Management to Reduce Manure P .............................................................................................. 4 Crop Management to Maximize P Removal ........................................................................................ 6 Transport of Manure P to a Larger Land Base .................................................................................. 8 Manure Treatment to Concentrate P ....................................................................................................... 8
OBJECTIVE OF THE REPORT .......................................................................................................... 8
METHODS .................................................................................................................................................. 9 CALCULATION OF P INPUTS ........................................................................................................................... 10
1. Animal Manure ......................................................................................................................................... 10 2. Synthetic Fertilizer .................................................................................................................................. 11 3. Seed ................................................................................................................................................................ 12 4. Atmospheric Deposition ...................................................................................................................... 12 5. Municipal Wastewater and Biosolids .......................................................................................... 13
CALCULATION OF P REMOVALS ................................................................................................................... 14 A. Harvested Plant Material .................................................................................................................... 14 B. Cattle Grazing on Pasture ................................................................................................................. 14 C. Residue Removal or Burning........................................................................................................... 15 D. Runoff ............................................................................................................................................................. 15 E. Wind Erosion ............................................................................................................................................. 15
RESULTS ................................................................................................................................................ 16 Table 5: P Inputs, Removals and Budgets by RM using 2011 Pig and Cattle Inventories .............................................................................................................................................................. 18 Map 1. Soil P budget estimates by RM for agro-Manitoba. .................................................... 21 Map 2. Soil P budgets (excluding synthetic fertilizer)by RM for agro-Manitoba. ....... 22
CONCLUSIONS ..................................................................................................................................... 23
ACKNOWLEDGMENTS ..................................................................................................................... 24
APPENDIX .............................................................................................................................................. 25 Table A.1. Phosphorus Contributions from Livestock in the RM of Arthur ..................... 25 Table A.2. Phosphorus Contributions from Seed for RM of Arthur ..................................... 26 Table A.3 Phosphorus Removals and P Budget for RM of Arthur ...................................... 27
REFERENCES AND ADDITIONAL READING ........................................................................... 28
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EXECUTIVE SUMMARY This report estimates soil phosphorus (P) budgets for each Rural Municipality
(RM) in agro-Manitoba with a focus on animal inventories, nutrient excretion and
crop production.
Original soil P budget estimates were made by Gyles (2009) using 2006 crop and
livestock inventory data from Statistics Canada. Significant reductions in cattle
and pig populations have occurred in Manitoba since 2006. Therefore, revised
estimates have been recalculated using 2011 pig and cattle numbers.
Of the 78 RMs assessed, the revised budgets demonstrated that most RMs in
southern agro-Manitoba are in P balance. In 15 RMs, mostly in the northern half
of agro-Manitoba, more P is being removed from the soil than is being replaced
with synthetic fertilizer and manure. There are only 9 municipalities that have a
surplus of P. Seven of these could achieve P balance by replacing synthetic
fertilizer inputs with manure. Two municipalities in Manitoba, specifically
Hanover and La Broquerie, have a significant P surplus due to livestock alone.
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BACKGROUND
Nutrient Use in Crop Production
Nitrogen (N) and phosphorus (P) have been identified as the most limiting
nutrients for crop production in Manitoba. To optimize crop yields, these two
elements must be supplied either as synthetic fertilizer or as an organic
amendment such as livestock manure.
Livestock manure is an important source of nutrients and can replace synthetic
fertilizer requirements. The beneficial use of manure in crop production has been
recognized since the early centuries when farmers would apply animal dung to
their land to boost crop yields. In addition to improving soil fertility, manure
encourages soil microbial activity and increases soil organic matter which
subsequently improves soil structure, water infiltration and water holding
capacity, increases cation exchange capacity and reduces wind and water
erosion.
There is increasing concern about the environmental impact of manure
application, particularly in areas of high livestock density where the land base is
limited. Manure is typically applied based on the N requirements of the crop.
Generally, the N:P ratio of manure is lower than the N:P ratio required by crops.
Thus, when manure is applied based on crop N requirements, P is applied in
excess of what is removed by the crop. The over-application of P is exacerbated
by the loss of manure N through ammonia volatilization which further reduces the
N:P ratio of the manure. Applications of P in excess of crop requirements results
in build-up of soil P which increases the risk of P transport to water bodies
through runoff, erosion and leaching (Sharpley et al.,1994; Lennox et al., 1997).
Phosphorus in surface water accelerates eutrophication, increases plant and
algae growth and can seriously degrade surface water quality.
Several methods are being explored to improve the N:P ratio of manure in order
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to reduce the accumulation of P in soil when manure is land applied based on N.
These methods include modifications to animal diets to reduce the amount of P
that is excreted in the manure, minimizing volatilization losses of N during
storage and land application as well as manure treatment technologies such as
solid-liquid separation. Solid-liquid separation of manure concentrates the P in
the solid fraction so that it can be transported more economically to lands that
are further away and have lower soil test P. Solid-liquid separation systems are
expensive to purchase, install and operate and may not be economically viable
for smaller livestock operations.
Soil P Budgets
In simple terms, a soil P budget includes all of the soil P inputs minus all of the
soil P removals. It can be calculated by field, farm or region.
Soil P budget = Soil P inputs – Soil P removals
Soil P inputs include synthetic fertilizer, livestock manure, wastewater biosolids,
other organic amendments, seed and atmospheric deposition. Soil P removals
include all of the P that is removed from the field or region in the harvested
portion of the crop such as grain, oilseed, hay or meat and bone (in the case of
pasture). Phosphorus can also be removed from the soil by runoff, erosion and
leaching.
Phosphorus balance indicates that P is being supplied at the same rate as it is
being removed. Provided soils have sufficient P fertility, fields, farms and regions
in P balance can be managed sustainably over the long-term.
A P deficit indicates more P is being removed from the field, farm or region than
is being supplied, primarily by synthetic fertilizer or manure. At the field level, P
deficits are unsustainable over the long-term as soils will be “mined” of P.
Eventually, a lack of soil P will limit plant growth and yields will suffer.
4
A P surplus indicates more P is being supplied than is being removed from the
field or region. At the field level, P surpluses will result in a build-up of soil test P.
Over the short-term this build-up will improve soil fertility and crop productivity,
but, over the long-term increasing soil test P will increase the risk of P loss to
surface and groundwater.
On-farm P budgets provide valuable information on the sustainability of P use on
the farm over the long-term. They can be used to make on-farm management
decisions to optimize P management. Regional P budgets, on the other hand,
provide only preliminary insight into the magnitude of any P imbalances in a
given region. They may be used for broad planning purposes but are not
appropriate for on-farm decision-making. This is due to the loss of detail with
aggregation of the data.
Aggregating data to calculate P balances at the regional scale occurs when
inputs and removals are collected or grouped by region. Although a region may
appear to be in P balance, it is highly unlikely that the entire area is uniform,
particularly if the region is very large. More likely, some operations within the
region will be in balance while others may have a P deficit or surplus. This is
because P inputs and removals are not equally distributed throughout a region.
The larger the area over which the P budget is calculated; the less meaningful
are the results at the local level. Therefore, significant aggregation, up to a
provincial or large watershed level, greatly diminishes the value of the P budget
results.
Management Options to Improve P Balance
Feed Management to Reduce Manure P
Maguire et al. (2005) reported that dietary manipulation strategies may offer the
most effective and economically viable means of improving the N:P ratio of
manure. These scientists further reported that a combination rather than
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individual strategies were needed. Various dietary manipulations have been
suggested and employed to reduce P in manure in order to reduce soil P loading.
The majority of P (>65%) in grains is phytate-bound and unavailable to
monogastric animals (pigs and poultry) that produce little or no enzyme required
for the dephosphorylation of phytate P (Selle and Ravindran 2007; Kiarie and
Nyachoti 2010). Consequently, available P is provided in the diet through
inclusion of supplemental, inorganic P.
Phytate-bound P can be made available through the inclusion of exogenous
phytase in the diet (Jongbloed and Lenis, 1997; Nyachoti et al. 2006; Yáñez et al.
2010). Most pig and poultry farmers now include exogenous phytase enzyme in
their ration. The use of phytase in the diet decreases the need for supplemental,
inorganic P in the diet. A reduction in the supplemental, inorganic P in the diet, in
turn, reduces the amount of P that is excreted in the manure.
The inclusion of phytase without reduction in supplemental, inorganic P in the
diet can increase P excretion in manure (Vadas et al. 2004; Angel et al. 2005). A
recent study in Manitoba suggested that supplemental P addition based on NRC
(1998) requirements is too generous and that there is room for further reductions
in P without negatively impacting animal performance (Nyachoti et al. 2011). In
2012, the 11th edition of the NRC report – Nutrient Requirements of Swine – was
released. While this edition builds on the work in previous editions, it has been
significantly updated to reflect rapidly emerging diet modifications.
The use of low phytate grains in the diet (Thacker et al., 2003; Leytem et al.,
2004) and feed ingredient processing (Zhang et al., 2003; Nyachoti et al., 2006)
can also result in a reduction in the total P excreted in the manure (Yi and
Kornegay, 1996; Jongbloed and Lenis, 1997, Ige et al., 2006, Ige et al., 2010).
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Low phytate P grains are genetically modified feedstuff that contains smaller
amount of phytate-bound P and greater amount of the readily available P. A
recent study conducted in Manitoba showed that feeding low phytate barley grain
feeds to finishing pigs significantly increased P digestibility and decreased P
excretion in pigs (Ige et al., 2010). The use of highly available P feed ingredients
will also reduce the need for supplemental P addition in feed and may offer some
economic benefit by reducing the cost of the ration. The use of low phytate P
grains is currently not being practiced in Manitoba, likely because low phytate
grains are not readily available on the market. The low phytate barley breed
produced at the CDC in Saskatoon was just released to the public for breeding in
2009.
Crop Management to Maximize P Removal
Crops vary considerably in their removal rates of P. Crop P removal is a function
of the quantity of P contained in the harvest portion of the crop and crop yield.
Table 1 demonstrates the very significant impact that crop yield can have on the
amount of P (expressed as the fertilizer equivalent, P2O5) removed per acre.
Good management practices – including soil management, pest control etc. –
that maximize yield potentials are essential. High P removal crops, such as high
yielding corn and alfalfa, can also be included in the rotation where appropriate to
maximize crop P removal.
Welsh et al. (2006) reported that a forage-based rotation (wheat – alfalfa – alfalfa
– flax) significantly reduced soil test P compared to an annual grain rotation
(wheat – pea – wheat – flax). Thus, crop rotation could be a useful management
system for regulating soil P build up and, consequently, P loss through run-off.
Brown et al. (2006) suggested that intensive cropping system which maximizes P
removal from soil can be beneficial for manure nutrient management. He
reported that double-cropping with winter forages and silage corn increased total
forage production, increased P removal, and reduced soil P concentrations more
7
than with corn alone. Ultimately, however, crop choices will depend on the
production system and market demand.
Pastures have the lowest P removals because the nutrients removed by the plant
are returned to the soil through animal manure during grazing. Maintaining P
balance on pastures that are being repeatedly fertilized with pig manure is
particularly challenging because P removals are so low.
Table 1. Rates of Phosphorus (as P2O5) removal for various crops Manitoba Yields (per acre)
2
Crop Removal P2O5 per unit of
crop1
MASC Lowest 20%
MASC Top 20%
P2O5 removed per acre (lb/ac)
Alfalfa 13.8 lb/ton 1.5 ton 4.2 ton 20.7 – 58.0
Barley – Grain 0.42 lb/bu 20 bu 76 bu 8.2 – 31.2
Canola – Argentine 1.04 lb/bu 9 bu 38 bu 9.4 – 39.5
Corn – Grain 0.44 lb/bu 7 bu 101 bu 3.1 – 44.4
Corn – Silage 12.7 lb/ton 1.33 ton 5.78 ton 16.9 – 73.4
Fababeans 1.79 lb/cwt 1020 lb 2550 lb 18.3 – 45.6
Flax 0.65 lb/bu 7 bu 23 bu 4.6 – 15.0
Grass hay3 10.0 lb/ton 0.49 ton 2.66 ton 4.9 – 26.6
Oats 0.26 lb/bu 36 bu 104 bu 9.4 – 27.0
Peas 0.69 lb/bu 9 bu 46 bu 6.2 – 31.7
Potatoes – rain fed 0.09 lb/cwt 39 cwt 270 cwt 3.5 – 24.3
Potatoes – irrigated 0.09 lb/cwt 114 cwt 272 cwt 10.3 – 24.5
Fall Rye 0.45 lb/bu 15 bu 65 bu 6.8 – 29.3
Soybeans 0.84 lb/bu 14 bu 38 bu 11.8 – 31.9
Sunflowers – not for oil 1.10 lb/cwt 310 lb 1850 lb 3.4 – 20.4
Sunflowers – for oil 1.10 lb/cwt 290 lb 2060 lb 3.2 – 22.7
Wheat – Spring 0.59 lb/bu 12 bu 42 bu 7.1 – 24.8
Wheat - Winter 0.51 lb/bu 19 bu 72 bu 9.7 – 36.7 1 Removals on a dry matter basis. Adapted from Managing Manure within Tillage Systems and Crop Rotations, Manure
Management Facts, MAFRI 2009. 2 Manitoba Agricultural Services Corporation, Static Map Library, Average Yield.
3 Grass hay yields can reach in excess of 4 tons/acre under good soil and fertility conditions.
8
Transport of Manure P to a Larger Land Base
In November 2013, the new soil test P thresholds under the Livestock Manure
and Mortalities Management Regulation (MR 42/98) come into force for all
livestock operations in Manitoba. Without improvements in on-farm P balance,
the need to haul manure P from areas of high livestock intensity to areas with
lower soil test P is inevitable. Transporting liquid manure over long distances is
very expensive.
Manure Treatment to Concentrate P
Mechanical solid-liquid separation systems are being implemented by some pig
farmers in Manitoba located in intensively developed areas. These systems,
however, are extremely expensive to purchase, install and operate. Manitoba
Agriculture, Food and Rural initiatives is currently offering to pay 75% of a solid-
liquid separation system up to $500,000 for pig operations to facilitate
compliance with the soil test P thresholds.
The adoption of multi-celled manure storage structures, and their management
as gravity separation systems that settle out the P-rich solids for transport out of
the region, may improve the economics of solid-liquid separation.
OBJECTIVE OF THE REPORT Regional P budgets provide insight into the P status of a region. They provide
preliminary information on the sustainability of the fertility practices in a region
and they could be incorporated into future policies on livestock development.
The objective of this report is to provide P budget estimates for each Rural
Municipality in agro-Manitoba. Original P budget estimates were made by Gyles
(2009) using 2006 livestock inventory data from Statistics Canada. However,
significant changes to the livestock industry, including reductions in cattle and pig
populations, have occurred since 2006.
9
Within the last decade, livestock operations have become more intensive. The
total number of livestock operations has declined while the number of animal per
operation has increased. Between 2001 and 2010, the number of pig farms in
Manitoba decreased from 1,668 to about 760, a decrease of more than 50%.
Within the same period, the number of pigs per farm increased from 1495 to
3400 (Honey, 2010; Statistic Canada, 2010).
Starting in 1995, pig production in Manitoba witnessed a steady growth until it
peaked in 2007. Various market conditions, environmental pressures and the
USA’s mandatory Country of Origin Labelling (COOL) legislation have
contributed to the gradual reduction in pig production. Annual pig production fell
from 9.45 million market hogs in 2007 to about 8.24 million in 2010, a drop of
12.8%.
The number of beef cattle farms in Manitoba has also decreased from 10,755 in
2002 to 8,500 in 2010. Total number of beef cattle increased from 1.39 million in
2002 to a peak value of 1.64 million in 2005 (Statistic Canada, 2006). Starting in
2006 there was a gradual reduction in the number of beef cattle in Manitoba. By
January of 2011 the number of cattle in Manitoba had fallen to 1.16 million, a
decrease of 29.3% since 2005.
Given the reduction in beef and pig numbers in Manitoba since 2006, revised P
budget estimates are warranted and are presented herein.
METHODS In order to create a P budget for a specific municipality it is necessary to
determine the P inputs and P removals for that RM. The approach used in the
Gyles (2009) model was similar to the approach developed by Nicolas et. al.
(2002). The all-encompassing approach used by Nicolas et. al. (2002) is
complex and can be simplified to the major components by focusing only on soil
10
inputs and outputs to develop a soil P budget estimate.
Soil P budget = Soil P inputs – Soil P removals
Calculation of P Inputs
The potential soil P inputs are:
1. Animal manure;
2. Synthetic fertilizer:
3. Seed;
4. Atmospheric deposition; and
5. Municipal waste
1. Animal Manure
The total manure P inputs for each RM were calculated as follows:
Manure P in RM for each Livestock Category = Number of Animals in RM x
Quantity of P Excreted per Animal per Cycle x Number of Cycles
Total Manure P inputs for each RM = ∑ Manure P in RM for all Livestock
Categories
Animal numbers for each RM were obtained from Statistics Canada’s 2006
Census of Agriculture and then adjusted using the January 2011 inventories of
cattle and pigs. The quantity of P excreted per animal per cycle and the number
of cycles for each livestock type are provided in Table 2. The P excretion
estimates (expressed as P2O5) for livestock in Manitoba (Table 2) are average
“book” values that were developed by Manitoba Conservation (Trudelle, 2008
adapted from Centre de Référence en Agriculture et Agroalimentaire du Québec,
2003). Actual P excretion depends on farm management and is strongly
influenced by feeding practices particularly the total amount of P in the diet.
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Table 2. P2O5 Excretion Estimates for Livestock in Manitoba Animal Type Kg Cycles
Dairy calves 14 1
Beef Backgrounder 16.5 1
Feeder cattle 16.5 1
Backgrounder 16.5 1
Cow/calf 27.4 1
Dairy cows 52 1
Dairy Heifers 32 1
Feeder cattle 27.4 1
Rams 6.04 1
Ewes 6.22 1
Lambs 0.74 1
Broilers 0.0402 6.5
Pullets under 19 0.068 2.5
Laying hens 19 weeks and over 0.367 1
Other poultry 0.07 1
Turkey (< 9,9 kg) 0.161 2.8
Boars 16.7 1
Sows and gilts for breeding 16.7 1
Nursing and weaner pigs 0.167 6.4
Grower and finisher pigs 2.05 2.9
Horses and ponies 14 1
Goats 3 1
Wild Boar 16.7 1
Bison 17 1
Llamas and Alpacas 6.22 1
Deer 14 1
Elk 14 1 Source: Adapted from Centre de Référence en Agriculture et Agroalimentaire du Québec, (2003) by Trudelle (2008)
2. Synthetic Fertilizer
The total synthetic fertilizer P inputs for each RM were calculated as follows:
Total Fertilizer P inputs for each RM = Total P2O5 sold in MB x Proportion $
spent in RM on fertilizer
The amount of P2O5 sold annually for agricultural purposes in Manitoba was
obtained from the Canadian Fertilizer Institute (2007).
The proportion of total provincial dollars spent on fertilizer that are spent in each
municipality was estimated using Census of Agriculture (2006) values. The total
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fertilizer P inputs for each RM was then calculated by multiplying the total amount
of P2O5 sold in Manitoba by the fraction of provincial fertilizer dollars spent in that
municipality.
3. Seed
The total seed P inputs for each RM were calculated as follows:
Total Seed P inputs for each RM = Total Crop Acres per crop x Seeding
Rate x Seed P Concentration
Phosphorus is also added to the soil in the form of seed when a field is seeded.
The total amount of seed-P added to soil in a municipality can be estimated by
determining crop acres for each crop type using the Census of Agriculture (2006)
values and multiplying the crop acres by the seeding rate and the amount of P in
the seed. Concentrations of P in seed were adapted from the Canadian Fertilizer
Institute (2001) values for P removal in crops. When these data were presented
as a range of values the midpoint value was used. Seeding rates and CFI
removal rates for P are shown in Table 3.
4. Atmospheric Deposition
Phosphorus that is added to soil from dust that settles out of the atmosphere or is
washed out of the atmosphere in precipitation is called atmospheric deposition.
Nicolas et. al. (2002) used a value of 0.1 kg P/ha/year. However, the quantity of
P that ends up on agricultural land as a result of atmospheric deposition is
assumed to be insignificant and as such was not included in the P budget
calculations.
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Table 3. CFI Crop P2O5 Removal Rates and Seeding Rates
Source: Gyles (2009) and Canadian Fertilizer Institute (2001)
5. Municipal Wastewater and Biosolids
Some municipalities may have a measureable amount of P added to agricultural
land in the form of municipal biosolids or irrigation of municipal waste-water.
Whether values for the amount of land-applied biosolids can be acquired is not
certain. The amount of P added to agricultural soils in the form of municipal
wastes was not included in the calculation of the P budgets.
Crop
low high units units/ac units alfalfa and mix 12 14.7 ton 2.5 lb
barley 0.375 0.463 bu 2 bu
canola 0.94 1.14 bu 0.120 bu
corn for silage 11.4 14 ton 0.214 bu
flax 0.583 0.7083 bu 0.589 bu forage seed 0.005 0.005 lb 5 lb
grain corn 0.39 0.48 bu 0.214 bu
mixed grains 0.43 0.43 bu 1.8 bu
oats 0.23 0.28 bu 2.3 bu other hay and fodder 9 11 ton 2 bu
rye 0.45 0.45 bu 1.2 bu
soybeans 0.8 0.857 bu 1.667 bu
spring wheat 0.525 0.65 bu 2 bu
sunflower 0.007 0.009 lb 4 lb winter wheat 0.46 0.56 bu 2 bu
durum 0.525 0.65 bu 2 bu
dry white beans 0.0138 0.0138 lb 60 lb
other dry beans 0.0138 0.0138 lb 60 lb canary seed 0.004 0.005 lb 40 lb
Field peas 0.62 0.76 bu 2 bu
potatoes 0.0825 0.1 cwt 23 cwt
mustard 0.94 1.14 bu 0.120 bu
buckwheat 0.009 0.0095 lb 42 bu triticale 0.525 0.65 bu 2 lb
P 2 O 5 removal lbs/unit Seeding Rate
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Calculation of P Removals
The potential soil P removals are:
A. Harvested plant material;
B. Cattle grazing on pasture;
C. Residue removal or burning;
D. Runoff; and
E. Soil erosion (wind and water)
A. Harvested Plant Material
Phosphorus is removed from the soil in the form of plants and plant products
such as grain and forage or meat in the case of grazing cattle on pasture. The
total P removed in each RM in the harvested portion of the plant can be
calculated as follows:
Crop P removal by crop type = Acres planted by crop x Long-term yield
average for each crop type x Crop P2O5 removal rate per unit of crop
Total Crop P Removal for the RM = ∑Crop P removals for all crops grown
Acres planted to each crop were obtained from 2006 Census of Agriculture data.
Long-term average yields (2001-2007) for each crop were calculated for each
municipality using Manitoba Agricultural Services Corporation (MASC) data. If a
specific yield was not available the average from a nearby municipality with
sufficient data was used. Crop P removal rates per unit of crop (Table 3,
expressed as P2O5) were adapted from the Canadian Fertilizer Institute (2007).
When data were presented as a range of values the midpoint value was used.
B. Cattle Grazing on Pasture
The total P removed in each RM in by cattle grazing on pasture can be
calculated as follows:
15
P removal by cattle grazing on pasture = Acres in pasture x 10 kg P2O5 per
acre
The P removal rate by cattle grazing on pasture was estimated at 10 kg P2O5 per
acre (Entz, 2008 pers. comm.). This rate is also consistent with Wilson et. al
(2010).
C. Residue Removal or Burning
An unknown amount of P could also be removed in the form of removed or
burned cereal and flax straw; however, the amount that is not eventually returned
to the land is assumed to be very small for most municipalities in Manitoba. As
such, P removal from cereal and flax straw removal or burning was not included
in the P budget calculation.
D. Runoff
The value used by Nicolas et. al. (2002) for the amount of soil P lost in run-off
was 0.3 kg P/ha/yr from perennial crops and 0.5 P/kg/ha/yr from annually
cropped land. This value was determined to be insignificant and as a result was
not included in the P budget calculation. Organic matter that is removed from the
soil during run-off will also remove P from the soil system. Nicolas et. al. (2002)
used 0.3 P/kg/ha/yr and 0.5 P/kg/ha/yr as the amount of actual P from organic
matter removed from perennial and annual crop land, respectively. This value
was also determined to be insignificant and as a result was not included in the
calculation.
E. Wind Erosion
Nicolas et al. (2002) found no literature values for the amount of P lost from soil
in the form of dust. This value was also determined to be insignificant and as a
result was not included in the calculation.
16
RESULTS The original P soil budgets calculated by Gyles (2009) using 2006 animal
inventories are shown in Table 4. Negative values indicate a P deficit while
positive values indicate a P surplus.
Table 4. Phosphorus Surplus or Deficit by RM Using 2006 Animal
Inventories
RM
Phosphorus Surplus or Deficit (kg P205/ha) RM
Phosphorus Surplus or Deficit (kg P205/ha)
Albert -0.91 Pipestone -1.73
Alexander -4.25 Portage la Prairie -0.78
Argyle -2.63 Reynolds -0.79
Armstrong -13.66 Rhineland 4.18
Arthur -6.63 Ritchot 2.49
Bifrost -4.36 Riverside 1.93
Brenda -2.98 Roblin -0.12
Brokenhead -0.48 Rockwood -3.12
Cameron -3.16 Roland 4.23
Cartier 10.82 Rosser -3.52
Coldwell -13.48 Sifton -6.99
Daly -0.64 Siglunes -9.64
De Salaberry 3.46 South Cypress 0.51
Dufferin 4.61 South Norfolk 8.37
Edward -7.93 Springfield 0.34
Elton 0.66 St. Andrews -4.04
Eriksdale -11.16 St. Clements -0.52
Fisher -6.87 St. Francois Xavier 1.53
Franklin -3.14 St. Laurent -11.38
Gimli -3.73 Stanley -0.75
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Table 4 Cont’d______________________________________________
Glenella -2.90 Ste. Anne 18.71
Glenwood -0.93 Strathcona 1.67
Grahamdale -8.68 Stuartburn -11.09
Grey 3.85 Tache 11.12
Hanover 35.63 Thompson 2.01
Headingley 4.82 Turtle Mountain 1.00
La Broquerie 101.01 Victoria -4.17
Lac du Bonnet -7.69 Wallace -2.46
Lakeview -9.89 West St. Paul 0.24
Lansdowne -2.05 Westbourne 1.71
Lorne 4.83 Whitehead -3.95
Louise -2.44 Whitemouth 11.21
Macdonald 4.85 Whitewater 0.02
Montcalm 3.26 Winchester -1.65
Morris 6.34 Winnipeg 11.98
Morton -7.32 Woodlands -6.50
North Cypress 3.73 Woodworth -7.38
North Norfolk 4.23 CAR 3* -9.27
Oakland -2.58 CAR 4* -11.51
Pembina 0.51 CAR 5* -8.10
Piney 2.04 CAR 6* -11.88
*In some areas RM level census levels violated privacy rules. For Census Agricultural Regions (CAR) 3 to 6 all RMs were aggregated.
Revised P budgets for each RM using 2011 inventories for cattle and pigs are
shown in Table 5. The reduction in pig and cattle numbers between 2006 and
2001 resulted in greater deficits and smaller surpluses across Manitoba. A
complete P budget for the RM of Arthur is provided in the Appendix (Tables A.1
to A.3).
18
Table 5: P Inputs, Removals and Budgets by RM using 2011 Pig and Cattle Inventories
19
Table 5: P Inputs, Removals and Budgets by RM using 2011 Pig and Cattle Inventories (cont’d)
20
Phosphorus budgets between -5 to +5 kg P2O5/ha were considered to be in
balance whereas P budgets less than -5 kg P2O5/ha were considered to be in
deficit and more than 5 kg P2O5/ha was considered to be in surplus.
Of the 78 RMs assessed, 51 were in or approaching P balance (Map 1). Fifteen
of the RMs and each of the remote Canadian Agricultural Regions (CARs 3 to 6)
showed a P deficit of greater than 5 kg P2O5/ha. Most of these RMs are located
in the northern half of agro-Manitoba (Map 1).
Nine RMs showed a P surplus due to a combination of synthetic P2O5 fertilizer
and manure inputs exceeding crop P2O5 removals by more than 5 kg P2O5/ha
(Map 1).
Excluding synthetic fertilizer from the calculation, although impractical, gives an
indication of the P budgets as a result of livestock alone. When synthetic
fertilizer is excluded, only Hanover and La Broquerie showed a P surplus due to
their livestock inventories (Map 2). As well, Ste. Anne appears to be
approaching P balance based on its livestock inventory (Map 2).
21
Map 1. Soil P budget estimates by RM for agro-Manitoba.
22
Map 2. Soil P budgets (excluding synthetic fertilizer)by RM for agro-Manitoba.
23
CONCLUSIONS
Significant reductions in cattle and pig populations in Manitoba since 2006
warranted a recalculation of soil P budgets by RM.
The revised budgets demonstrated that most municipalities in southern agro-
Manitoba are in P balance. This indicates that these RMs are replacing the P
that is removed in the harvested portion of the crop with synthetic fertilizer and
manure. Soil fertility in these RMs should be sustainable over the long-term if
beneficial management practices are employed.
In 15 RMs, mostly in the northern half of agro-Manitoba, more P is being
removed from the soil than is being replaced with synthetic fertilizer and manure.
A P deficit indicates that these RMs are “mining” the soil of P. This practice
results in decreased yields and is not sustainable over the long-term.
There are only 9 municipalities that have a surplus of P. Seven of these could
achieve P balance by replacing synthetic fertilizer inputs with manure. Two
municipalities in Manitoba, specifically Hanover and La Broquerie, have a
significant P surplus due to livestock alone.
Management of P surpluses at the farm level requires more detailed on-farm P
budgets to determine which operations have the surplus and the magnitude of
the problem. Phosphorus surpluses at the farm level result in over-application of
manure P to land, build-up of soil test P and will make compliance with the soil
test P thresholds challenging. These operations should explore all opportunities
to minimize feed P and synthetic P fertilizer inputs to reduce their P surpluses.
Where P balance cannot be achieved, more intensive P management strategies
– including export of manure P with or without treatment or a reduction in animal
numbers – will be required to bring these operations into P balance.
24
Acknowledgments
Funding was provided by the Agri-Food Research and Development Initiative
(ARDI) under the Canada-Manitoba Growing Forward Initiative, and by the
Manitoba Livestock Manure Management Initiative.
The authors would like to acknowledge the contributions of Ron Tone and Joel
Tone of Tone Ag Consulting Ltd. who supplied information regarding manure
production per animal species.
The authors would also like to acknowledge Ian Kirby of MAFRI for preparing the
Soil Phosphorus Budget maps.
25
APPENDIX
Table A.1. Phosphorus Contributions from Livestock in the RM of Arthur
1.0 ADDITIONS 1.1 Manure /year P205/head Animals P205 (Kg) Dairy calves 1 14 3244.01 45416.13 Beef Backgrounder 1 16.5 467.1 7707.15 Feeder cattle 1 16.5 302.058 4983.957 Backgrounder 1 16.5 400.9275 6615.304 Cow/calf 1 27.4 4039.637 110686 Dairy cows 1 52 0 0 Dairy Heifers 1 32 0 0 Feeder cattle 1 27.4 202.41 5546.034 Total Cattle P205 (Kg) 2011 Inventories
/year P205/head Animals P205 (Kg) Rams 1 6.04 9 54.36 Ewes 1 6.22 310 1928.2 Lambs 1 0.74 383 283.42 Total Sheep P205 (Kg)
Animals P205 (Kg) Broilers, roasters and Cornish hens 6.5 0.0402 426 111.3138 Pullets under 19 weeks intended for laying 2.5 0.068 134 22.78 Laying hens 19 weeks and over 1 0.367 94 34.498 Other poultry 1 0.07 15 1.05 Turkey (< 9,9 kg) 2.8 0.161 50 22.54 Total Poultry P205 (Kg)
Animals P205 (Kg) Boars 1 16.7 3.5648 59.53216 Sows and gilts for breeding 1 16.7 20.4976 342.3099 Nursing and weaner pigs 6.4 0.167 20.4976 21.90783 Grower and finisher pigs 2.9 2.05 20.4976 121.8582 Total Hog P205 (Kg) 2011 Inventories
8.38654 Animals P205 (Kg)
Horses and ponies 1 14 201 2814 Goats 1 3 59 177 Wild Boar 1 16.7 0 0 Bison 1 17 0 0 Llamas and Alpacas 1 6.22 3 18.66 Deer 1 14 0 0 Elk 1 14 0 0
TOTAL Manure P2O5 ADDITIONS (KG)
2265.98
3009.66
545.61
186968.0478
RM of Arthur
192.1818
180954.6179
26
Table A.2. Phosphorus Contributions from Seed for RM of Arthur
1.2 Fertilizer
Total Manitoba Fertilizer Expenditure $351,136,399
CFI P205 Sold in MB (Kg) 106,600,000 $ P205 (Kg)
Fertilizer and Lime Expenidure / R.M. 2886406 876,271.67
Total Fertilizer P205 (Kg)
1.3 Seed
2006 CROPS (acres)
P2O5 additions lbs/unit units/ac
low high Seeding Rate Units Acres P205 (lbs)
alfalfa and mix 0.0050 0.0050 2.5 lb 12991 162.3875
barley 0.38 0.46 2 bu 4990 4181.62
canola 0.94 1.14 0.120 bu 23222 2898.1056
corn for silage 0.39 0.48 0.214 bu 1205 112.323214
flax 0.58 0.71 0.589 bu 6258 2380.99579
forage seed 0.0050 0.0050 5 lb 213 5.325
grain corn 0.39 0.48 0.214 bu 778 72.5207143
mixed grains 0.43 0.43 1.8 bu 123 95.202
oats 0.23 0.28 2.3 bu 15068 8645.265
other hay and fodder 0.38 0.46 2 bu 3113 2608.694
rye 0.45 0.45 1.2 bu 6591 3559.14
soybeans 0.80 0.86 1.667 bu 0 0
spring wheat 0.53 0.65 2 bu 48721 57247.175
sunflower 0.0070 0.0090 4 lb 11429 365.728
winter wheat 0.46 0.56 2 bu 1983 2022.66
Durum 0.53 0.65 2 bu 857 1006.975
dry white beans 0.0138 0.0138 60 lb 0 0
other dry beans 0.0138 0.0138 60 lb 439 363.492
canary seed 0.0040 0.0050 40 lb 120 21.6
Field peas 0.62 0.76 2 bu 1610 2221.8
potatoes 0.0825 0.10 23 cwt 148 310.615
mustard 0.94 1.14 0.120 bu 239 29.8272
buckwheat 0.0090 0.0095 42 bu 118 45.843
triticale 0.53 0.65 2 lb 0 0
Sum 88357.294
TOTAL SEED P2O5 ADDITIONS (KG) 40,078.87
876271.6724
27
Table A.3 Phosphorus Removals and P Budget for RM of Arthur
2.0 REMOVALS
2.1 Crops P2O5 removal lbs/unit
(except straw)
Crop low high Units Avg Yield (tonne/acre)P205 (lb)
alfalfa and mix 12 14.7 Tons 1.487 257890.187
barley 0.375 0.463 bu 50.305 105178.197
canola 0.94 1.14 bu 24.735 597372.017
corn for silage 11.4 14 Tons 7.22 110491.27
flax 0.583 0.7083 bu 16.711 67520.4228
forage seed 0.005 0.005 Lbs 546.74 582.2781
grain corn 0.39 0.48 bu 38.173 12918.8884
mixed grains 0.43 0.43 bu 43.926 2323.24614
oats 0.23 0.28 bu 68.461 263050.439
other hay and fodder 9 11 Tons 1.22 37978.6
rye 0.45 0.45 bu 41.567 123285.644
soybeans 0.8 0.857 bu 0 0
spring wheat 0.525 0.65 bu 31.783 909743.482
sunflower 0.007 0.009 lbs 1177.2 107633.75
winter wheat 0.46 0.56 bu 46.063 46584.8938
Durum 0.525 0.65 Bu 22.893 11526.3393
dry white beans 0.0138 0.0138 Lbs 0 0
other dry beans 0.0138 0.0138 Lbs 1406.5 8520.8583
canary seed 0.004 0.005 Lbs 595.7 321.678
Field peas 0.62 0.76 Bu 38.17 42403.053
potatoes 0.0825 0.1 cwt 233.488 3153.25544
mustard 0.94 1.14 bu 706.8 175682.208
buckwheat 0.009 0.0095 lbs 564.37 616.009855
triticale 0.525 0.65 bu 0 0
Sum lbs 2884777
TOTAL CROP P2O5 REMOVALS (KG)
2.2 Pasture
Acres tons/ acre P2O5 removal kgs/unit
Pasture Removal Rate 1 9 11
TOTAL PASTURE P2O5 REMOVALS (KG)
TOTAL P2O5 REMOVALS (KG)
3.0 ADDITIONS - REMOVALS
Net Total (Kg)
Land (ha)
Surplus (kg/ha)
Surplus (lbs/acre)
1623809.609
-7.36
-6.56
31527.489
70737
1,308,535
315274.89
-520,491
28
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