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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

1

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.

2

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

3

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

5

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).

6

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.

11

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

12

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.

13

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

14

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

17

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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