Soil Fertility and Nutrient Use: Manure Management

| Corn | Soybeans | Forages | Cereals | Dry Edible Beans |
| Spring and Winter Canola | Other Crops | Soil Management |
| Soil Fertility and Nutrient Use | Field Scouting |
| On-Farm Stored Grain Management | Weed Control |
| Insects and Pests of Field Crops | Diseases of Field Crops | Appendices |

Pub 811: Agronomy Guide > Soil Fertility and Nutrient Use > Manure Management

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

 

The Value of Manure

The value of manure in crop production is often under-estimated. Manure contains all of the nutrients needed by crops but not necessarily in the proportions needed for specific soil and crop conditions. In addition to nitrogen, phosphorus and potash, manure contains many secondary nutrients and micronutrients, as well as organic matter that help build and maintain soil structure.


An Example

A farmer spreads 45,000 L of liquid finisher swine manure per hectare (4,000 gal per acre) in the spring, working the manure into the soil within 24 hours.

Fertilizer Equivalent Amt Price/kg1 Value/ha
Nitrogen
153 kg/ha
x 1.90
= $290.70
P205
66 kg/ha
x 2.50
= $165.00
K20
96 kg/ha
x 1.50
= $144.00
Total value per hectare
= $599.70

The equivalent amount of commercial fertilizer can be calculated using Table 9-8, Typical Amounts of Available Nitrogen, Phosphate and Potash From Different Types of Organic Nutrient Sources, and Table 9-13, Typical Manure Analysis by Livestock Type. At the sample prices for commercial fertilizer shown in this chart, the approximate value of the manure is $600/ha ($243/acre), assuming that all nutrients are needed by the crop.

1 Price based on average commercial fertilizer costs in 2008.


Nutrient Management Plans

A nutrient management plan matches the nutrients available from manure, cover crops, commercial fertilizer and the soil to the nutrients required by the crop. Analysis of nutrients contained in the manure, along with soil test results and crop requirements, help determine the manure application rate and additional commercial fertilizer requirements.

A nutrient management plan may restrict the rate of manure or fertilizer applied if that application could create certain risks, as shown below:

Criteria
Risk
Nitrogen nitrate leaching into groundwater
Phosphorus phosphate movement into surface water
Volume of liquid direct runoff, carrying ammonia, phosphate and pathogens

 

Table 9-8. Typical Amounts of Available Nitrogen, Phosphate and Potash From Different Types of Organic Nutrient Sources
Type
D.M. Available N Available P205 Available K20
Fall1 Spring2 Spring inject3
Liquid Materials
%
kg/1000 L (lb/1,000 gal)
Hog finisher
7.6
3.1 (30.7)
3.8 (38.2)
4.9 (49.4)
2.1 (21)
3.2 (32)
Hog weaners
3.0
1.6 (15.8)
2.0 (19.9)
2.6 (25.7)
1.3 (13)
1.7 (17)
Hog SEW
2.2
1.3 (12.5)
1.5 (14.8)
1.9 (18.9)
0.6 (5.5)
1.4 (14)
Hog dry sows
1.9
1.3 (13.0)
1.8 (18.3)
2.4 (24.1)
0.9 (9.2)
1.2 (12)
Dairy liquid ave
8.4
1.4 (14.4)
1.5 (15.4)
1.9 (19.2)
0.8 (7.7)
2.6 (26)
Dairy 10%-18%
14
2.0 (20.1)
2.0 (19.7)
2.4 (24.2)
1.3 (13)
3.4 (34)
Dairy 6%-10%
8.0
1.5 (14.8)
1.6 (16.2)
2.0 (20.2)
0.7 (6.9)
2.6 (26)
Dairy 2%-6%
4.4
1.0 (9.8)
1.2 (11.6)
1.5 (14.7)
0.5 (5.0)
2.0 (20)
Beef liquid ave
7.9
1.3 (12.7)
1.4 (13.6)
1.7 (16.9)
0.7 (7.3)
2.3 (23)
Beef 10%-18%
15
2.0 (19.7)
1.9 (19.1)
2.3 (23.3)
1.2 (12)
3.6 (36)
Beef 6%-10%
7.8
1.4 (13.5)
1.5 (14.5)
1.8 (18.2)
0.7 (7.2)
2.2 (22)
Beef 2%-6%
3.8
0.9 (8.6)
1.1 (10.6)
1.4 (13.6)
0.5 (4.5)
4.6 (16)
Runoff 0%-2%
0.7
0.2 (2.1)
0.3 (2.7)
0.4 (3.5)
0.1 (1.0)
0.9 (9.2)
Poultry liquid ave
11
4.2 (41.8)
5.0 (49.6)
6.4 (63.5)
14 (28)
16 (32)
Biosolids aerobic
2
0.5 (5.0)
0.4 (4.1)
0.4 (4.4)
0.6 (5.5)
0
Biosolids anaerobic
4.4
1.2 (11.8)
1.2 (11.8)
1.4 (13.8)
1.3 (13)
0

 

Type
D.M. Available N Available P205 Available K20
Fall1 Spring2 Spring inject3
Solid Materials
%
kg/tonne (lb/ton)
Hog solid average
30
3.1 (6.1)
3.6 (7.2)
4.3 (8.6)
4.3 (8.5)
6.0 (12)
Dairy 18%-30%
21
1.7 (3.4)
2.1 (4.2)
2.4 (4.8)
1.5 (3.0)
5.0 (10)
Dairy 30% +
39
2.0 (3.9)
2.1 (4.1)
2.3 (4.5)
1.6 (3.1)
5.5 (11)
Beef 30% +
38
2.9 (5.7)
2.4 (4.8)
2.7 (5.3)
3.5 (6.9)
8.0 (16)
Beef 18%-30%
24
1.9 (3.8)
1.9 (3.7)
1.2 (4.2)
1.5 (3.0)
5.0 (10)
Horses average
37
1.5 (3.0)
1.4 (2.8)
1.6 (3.1)
1.4 (2.8)
4.7 (9.3)
Sheep average
34
3.2 (6.4)
3.8 (7.5)
4.5 (8.9)
2.6 (5.2)
8.4 (16.7)
Poultry layers
34
8.7 (17.4)
9.3 (18.6)
11.3 (22.5)
8 (16)
8.5 (17)
Poultry pullets
48
12.2 (24.5)
12.7 (25.3)
14.5 (28.9)
13 (25)
15 (29)
Poultry broilers
68
10.8 (21.6)
11.3 (22.5)
12.4 (24.7)
13 (25)
17 (33)
Biosolids dewatered
32
11.3 (22.6)
12.3 (25.6)
13.7 (27.3)
12 (24)
1.2 (2.4)

1 Late fall application or early application with cover crop.
2 Spring application incorporated within 24 hours.
3 Injection or immediate incorporation, assumes good coverage.

Availability of Manure Nitrogen to Crops

The amount of nitrogen contained in manure that is available to crops will depend on the characteristics of the manure, the time that it is applied and how soon following application the manure is incorporated into the soil. The relevant manure characteristics are the total N content, the proportion that is in the mineral (ammonium) and organic forms, and the rate of breakdown of the organic material to release mineral N.

Mineral Nitrogen From Manure

Ammonium-N (NH4-N) is immediately available to the crop, as nitrogen is from mineral fertilizers, but it is also subject to volatile loss to the air. Manure from different farming systems contains varying proportions of organic and ammonium-N. Liquid manure contains a higher proportion of the nitrogen in the ammonium form than solid manure. The proportion of ammonium-N and organic-N can be determined from a manure analysis, or estimated from the values in Table 9-9, Approximate Ammonium-Nitrogen as a Percentage of Total Nitrogen in Various Manure Types.

Table 9-9. Approximate Ammonium-Nitrogen as a Percentage of Total Nitrogen in Various Manure Types
Type Ammonium
Liquid Manure1
Liquid hog
66 %
Liquid dairy
42%
Liquid beef
43%
Liquid poulty
67%

 

 
Type Ammonium
Solid Manure
Solid hog
26%
Solid dairy
21%
Solid beef (high bedding)
12%
Solid horse
15%
Solid poultry (broilers)
6%
Solid poultry (layers)
46%
Composted cattle
0.6%

 

Type Ammonium
Muncipal Biosolids
Aerobic sewage biosolids
1.6%
Anaerobic sewage biosolids
35%
Dewatered sewage biosolids
12%
Lime Stabilized sewage biosolids
trace
Paper Mill biosolids
trace
Spent Mushroom compost
5

Source: NMAN software.

1 Ammonium content increases as liquid concentration increases.
2 Balance of nitrogen is in organic form.

As soon as the manure is applied to the field, the ammonium-N starts to volatilize into the air. This process continues until the manure is moved into the soil by incorporation or rainfall, or until the ammonium-N in the manure is depleted to the point that it is stable. Manures that are incorporated quickly will provide much more nitrogen to the crop. The rate of ammonium-N loss will depend on the soil moisture and weather conditions at the time of application. Moist soils increase the opportunity for ammonium to be absorbed in the soil water. Warm temperatures increase the rate of ammonium loss to the air. The estimated losses under various conditions are listed in Table 9-10, Estimated Percentage of Ammonium-N Lost Due to Weather and Soil Conditions.

The balance of ammonium-N that remains in the soil is available for crop uptake, or for loss to the environment if there is no crop present to take up the nitrogen.

Table 9-10. Estimated Percentage of Ammonium-Nitrogen Lost Due to Weather and Soil Conditions
Days After Application Average Cool
(<10°C)
Warm (>25°C)
Wet Dry Wet Dry
Spring
Incorporated within 1 day
25
10
15
25
50
Incorporated within 2 days
30
13
19
31
57
Incorporated within 3 days
35
15
22
38
65
Incorporated within 4 days
40
17
26
44
73
Incorporated within 5 days
45
20
30
50
80
Not incorporated
66
40
50
75
100
Injected (covered)
0
0
0
0
0

 

 
Days After Application Average Cool
(<10°C)
Warm
(>25°C)
Wet Dry Wet Dry
Summer/early fall (with or without incorporation)
Bare soil
66
40
50
75
90
Crop residue
50
30
35
60
70
Standing crop (below the canopy)
35
25
25
40
50
Late fall-applied
25
25
25
N/A
N/A

Adapted from Beauschamp, University of Guelph, 1995.

Organic Nitrogen from Manure

Organic nitrogen is not available to the crop until it has been mineralized to the ammonium form by microbial action. The amount of mineralization will vary with the type of manure, as the organic material in some manure is more resistant to breakdown than in others. As a general rule, the organic-N will become available more quickly from manure from animals receiving a concentrate-based diet compared to a forage-based diet. The percentage of available nitrogen available from the organic portion of manure is shown in Table 9-11, Estimated Percentage of Organic Nitrogen Available in Year of Application. The speed of mineralization increases with warm temperatures and adequate moisture, which promote microbial growth, and will almost stop when soil temperatures approach freezing. Nitrogen from solid manure applied just before planting may not be available in time to meet the requirements of the crop.

Ammonium-N, whether applied directly or from the mineralization of organic-N, is further converted to nitrate-N by microbial action in the soil. Unlike ammonium-N, which will adhere to soil particles, the nitrate ion can move freely with soil water.

Loss of nitrate-nitrogen (NO3-N) through leaching or denitrification will occur if manure (especially liquid manure that is high in NH4-N) is applied in the summer or early fall. The amount of loss will depend on how much nitrate-N is produced, which in turn depends on the time required for ammonium-N and organic-N to be converted to nitrate-N. Late-summer applications of manure have a greater chance of nitrate-N losses than manure applied just before freeze-up or in the spring.

Table 9-11. Estimated Percentage of Organic Nitrogen Available in Year of Application
Manure Type %
Liquid - poultry

0.3
Liquid - all other
0.2
Liquid & solid - biosolids
0.3
Solid - poultry/mink/fox
0.3
Solid - swine
0.25
Solid - < 50% DM
0.15
Solid - > 50 % DM*
0.05

Cover crops can help retain the nitrogen from manure applied in the summer or early fall.

Field trials with specific livestock manure types to determine how much nitrogen would be available to crops the following year has resulted in Table 9-12, Estimate of Available Nitrogen From Late Summer- and Fall-Applied Manure. To estimate the amount of nitrogen available to the crop, multiply the amount of manure nitrogen applied to the field by the availability factor appropriate for the manure type and application timing. For example, if 45,000 L/ha (4,000 gal/acre) of liquid hog finishing manure is applied in late summer, supplying 285 kg/ha (256 lb/acre) of total N, reduce the N fertilizer application to the following crop by 57 kg/ha (51 lb/acre) (285 lb/acre total N x 0.2 availability factor).

Table 9-12 accounts for the volatilization of ammonium-N into the air, the mineralization of organic-N and the loss of nitrate through denitrification or leaching. A large part of the ammonium-N will be lost to the air if manure is left on the soil surface so the proportion of nitrogen available to the crop is greater with incorporated manure. Assumptions have been made concerning the proportion of nitrogen in the ammonium and organic forms (see Table 9-9) and the availability of the organic nitrogen. Urea has been included as an example of how fertilizer nitrogen availability compares with that of manure. These factors can be used with the results of a manure analysis or the values in Table 9-13, Typical Manure Analysis by Livestock Type, to estimate nitrogen availability.

Manure Analysis

Manure analysis is necessary because the quantities of nutrients contained in manure will vary from farm to farm, especially the phosphorus and potash components. Type of livestock, ration, bedding, added liquids and storage system all affect the final nutrient analysis. Phosphorus tends to be concentrated in the solids, while potassium levels tend to be higher in the liquid portion, therefore the level of agitation will affect nutrient levels being applied to a field. Fertilizer adjustments based on a manure analysis will be more accurate than those based on average values.

Table 9-12. Estimate of Available Nitrogen From Late Summer- and Fall-Applied Manure
Application Time Available Nitrogen 1,2
Incorporated
(<24 hours)
Not Incorporated3
Late Summer Early Fall Late Fall Early Fall Late Fall
Urea (commercial N)
0.1
0.2
0.5
0.1
0.4
Solid cattle/sheep
0.3
0.3
0.3
0.25
0.2
Solid poultry
0.3
0.4
0.5
0.3
0.3
Liquid cattle
0.3
0.4
0.5
0.3
0.4
Liquid swine
0.2
0.3
0.4
0.2
0.3
Liquid biosolids
0.3
0.4
0.5
0.3
0.4

Source: Adapted from Barry et. al., University of Guelph, 2000.
Available N in manure = total manure N applied x available N from Table 4.

1 Assumes a spring-planted crop.
2 Accounts for ammonia loss to atmosphere and mineralization of organic N.
3 For manure incorporated within 3 days, use (incorporated value + non incorporated value) ÷ 2.

Above-average levels of nitrogen, phosphorus or trace elements in manure may be an indication that dietary levels are higher than required. Amino acid balancing for nitrogen, reducing the amount of phosphorus in the mineral supplements or the addition of phytase (an enzyme that increases phosphorus efficiency in the animal) may be methods that can help reduce these nutrients in manure. A livestock nutritionist should be consulted before making ration changes.

Manure analysis is available from several laboratories in Ontario. Sample after complete agitation or thorough mixing each time the storage is emptied (i.e., spring and fall) and send the sample for analysis. After several analyses, a trend in results should become evident. As well, sample any time there are changes in ration or other management factors.

When sending a sample to the lab, fill a plastic jar about half-full, secure the top, place in a plastic bag and store in a cool place until shipping. Analysis should include total nitrogen, ammonium-nitrogen (NH4-N), phosphorus, potassium and dry matter. Ontario labs return analysis results with percentages for nitrogen, phosphorus, potassium and dry matter, as well as mg/kg (or ppm) of ammonium nitrogen. On most reports, percentages of phosphorus and potassium from manure are converted to phosphate and potash equivalents, and commercial fertilizer reductions are often reported.

Table 9-13. Typical Manure Analysis by Livestock Type (fresh weight basis)
DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Hog
Solid average
S
30
0.90
0.27
0.46
0.56
Liquid average
L
3.7
0.40
0.27
0.13
0.18
Finisher
L
7.6
0.64
0.45
0.23
0.30
Weaners
L
3.0
0.33
0.23
0.14
0.16
Sow
L
2.2
0.26
0.17
0.06
0.13
Dry sows
L
1.9
0.27
0.23
0.10
0.11

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Dairy
Solid average
S
25
0.59
0.12
0.17
0.49

30% +

S
39
0.65
0.08
0.17
0.53
18%—30%
S
21
0.57
0.13
0.16
0.48
Liquid average
L
8.4
0.35
0.15
0.08
0.24
10%—18%
L
14
0.49
0.18
0.14
0.32
6%—10%
L
8.0
0.36
0.16
0.07
0.24
2%—6%
L
4.4
0.24
0.12
0.05
0.19

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Beef
Solid average
S
25
0.59
0.12
0.17
0.49

30% +

S
39
0.65
0.08
0.17
0.53
18%—30%
S
21
0.57
0.13
0.16
0.48
Liquid average
L
8.4
0.35
0.15
0.08
0.24
10%—18%
L
14
0.49
0.18
0.14
0.32
6%—10%
L
8.0
0.36
0.16
0.07
0.24
2%—6%
L
4.4
0.24
0.12
0.05
0.19

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Runoff
0%—2%
L
0.7
0.05
0.03
0.01
0.09

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Horses
0%—2%
S
37
0.50
0.07
0.15
0.43

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Sheep
Average
S
34
0.80
0.23
0.28
0.78
80% +
S
85
3.36
0.21
1.69
1.74

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Poultry
Layers
S
34
1.93
0.78
0.89
0.80
Pullets
S
48
3.14
0.72
1.36
1.35
Broilers
S
68
3.09
0.44
1.33
1.52
Liquid average
L
11
0.82
0.56
0.30
0.30

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Poultry
Layers
S
34
1.93
0.78
0.89
0.80
Pullets
S
48
3.14
0.72
1.36
1.35
Broilers
S
68
3.09
0.44
1.33
1.52
Liquid average
L
11
0.82
0.56
0.30
0.30

1 To convert from % to ppm, multiply by 10,000.

DM Range Solid/
Liquid
Ave.
DM
Total
N
Total Nutrient Content
(as-is basis)
% % % NH4-N1 P K
Biosolids
Aerobic
L
2.0
0.12
0.01
0.06
0
Anaerobic
L
4.4
0.28
0.08
0.14
0
Dewatered
S
32
3.76
0.34
1.31
0.11

1 To convert from % to ppm, multiply by 10,000.

Details for interpreting a manure analysis are shown in Calculating Available Nutrients from Spring-Applied Manure Using a Manure Analysis, next page. Information from a manure analysis, plus knowledge of the conditions at the time the manure was applied, can be used to provide a more precise estimate of the available nutrients in the manure applied to your fields.

Nutrient Losses From Manure

There are two nitrogen components in manure. Ammonium-nitrogen makes up the largest percentage of the nitrogen in liquid manure with approximate percentages listed by livestock type in Table 9-9, Approximate Ammonium-Nitrogen as a Percentage of Total Nitrogen in Various Manure Types. The organic-N component is available over time as the organic matter breaks down, similar to a slow-release nitrogen fertilizer. About 20%-30% of the organic nitrogen component of manure is assumed to be available to a growing crop in the year of application. The percentage is generally higher in poultry and lower for ruminant livestock manure.

Ammonium-N is immediately available to a growing crop but is also easily lost to volatilization unless incorporated soon after application. Soil moisture and weather conditions will determine how quickly and how much loss to expect. These losses are highest on sunny, warm days, when soils are dry; losses are lowest when conditions are overcast and cold (<10°C), when soils are moist or during rainy periods. Table 9-10, Estimated Percentage of Ammonium-Nitrogen Lost Due to Weather and Soil Conditions, gives estimated losses due to weather and soil conditions only for the ammonium-nitrogen component of manure. With manure applied in late fall, the losses are low since cooler temperatures slow down microbial action in soil, which minimizes conversion. Losses can be high due to runoff from late fall applications, especially when not incorporated. Denitrification and leaching losses of nitrogen are dealt with in Nitrogen Risk Mitigation.

Table 9-11, Estimated Percentage of Organic Nitrogen Available in Year of Application, gives estimated nitrogen available from the organic nitrogen portion of the manure based on livestock type.

Long-Term Value of Manure

The long-term availability of phosphorus (P), potassium (K), magnesium, zinc or manganese from previous manure applications is best estimated by soil testing. Application of large quantities of manure over time can result in high levels of available P and K in soils. Manure also provides organic matter and other plant nutrients to the soil that will contribute to improved soil physical structure and buffering capacity.

Calculating Available Nutrients from Spring-Applied Manure Using a Manure Analysis
Available Nitrogen1   Available Phosphate2   Available Potash2  
A. Total Nitrogen   H. Total Phosphorus   K. Total Potassium  
B. Ammonium-N   I. Available Phosphorus
(H x 0.4)
  L. Available Potassium
(K x 0.9)
 
C. Organic N3
(A-B)
  J. Available Phosphate
(I x 2.29)
  M. Available Potash
(L x 1.2)
 
D. Ammonium Losses
(B x factor from Table 9-10)
         
E. Available Ammonium
(B-D)
         
F. Available Organic N
(C x factor from Table 9-11)
         
G. Total Available N
(E+F)4
         

1 Available nitrogen is determined by subtracting the ammonia losses to the air from the ammonium-N applied and adding the mineralization from the organic N portion of the manure.
2 Calculate reductions in fertilizer phosphate and potash by determining the available portion of the total P and K in the manure (40% for phosphorus and 90% for potassium) and multiplying by a factor to convert from the elemental form to the oxide form (fertilizer nutrients are expressed in the oxide form). In the year of application, 40% is available; another 40% is available in following year.
3 Organic N will also give an N credit for several years after application: 10% in 2nd year, 5% in 3rd year, x 2% in 4th year.
4 To estimate the available N from summer or fall applications of manure, multiply the Total N content by the appropriate factor in Table 9-12, Estimate of Available Nitrogen From Late Summer- and Fall-Applied Manure.


For Values in Percent

To get

kg/1000 L multiply by 10
lb/1,000 gal multiply by 100
kg/tonne multiply by 10
lb/ton multiply by 20


Example: Dairy manure is spring applied at (5,000 gal/acre) under cool, dry conditions ahead of planting corn (incorporated within 3 days); DM content is 7%; total N is 0.65%; ammonium N is 0.35%; total P is 0.2%, total K is 0.3% (as-is basis)

Available Nitrogen1   Available Phosphate2   Available Potash2  
A. Total Nitrogen
0.65
H. Total Phosphorus
0.2
K. Total Potassium
0.3
B. Ammonium-N
0.35
I. Available Phosphorus
(H x 0.4)
0.08
L. Available Potassium
(K x 0.9)
0.27
C. Organic N3
(A-B)
0.30
J. Available Phosphate
(I x 2.29)
0.18
M. Available Potash
(L x 1.2)
0.32
D. Ammonium Losses
(B x factor from Table 9-10)
0.13
  
E. Available Ammonium
(B-D)
0.22
F. Available Organic N
(C x factor from Table 9-11)
0.06
G. Total Available N
(E+F)4
28
Nutrients lb/1,000 gallons
28
  18   32

An electronic version of this worksheet can be found in the OMAFRA NMAN software or as a spreadsheet at www.gocorn.net.

Most of the available nitrogen in manure is used by the crop or is lost during the first growing season following application. The remaining organic nitrogen becomes available in small, diminishing quantities in the succeeding years. Generally, the amount of residual nitrogen from one application of liquid manure is too small to make a practical difference in nitrogen recommendations for a crop. However, where solid manure is applied regularly to the same field, there can be significant residual nitrogen available for a crop. Use regular soil testing for P and K to measure residual levels of these nutrients from manure applications.

Crop Requirements

Soil test results and yield goals will determine the maximum economic manure application rate and/or additional fertilizer requirements. Often soil test levels on livestock farms indicate that soil fertility levels are high enough that we do not expect any response to additional fertility.

An alternative to determining application rates from soil test values is to apply manure based on the amount of nutrients removed by a crop and then match phosphorus and/or nitrogen from manure to determine an application rate. In theory this method should keep soil fertility levels constant. Table 9-14, Average Nutrient (N, P, K) Removal by Common Field Crops, will help determine the average nutrient removal for various crops.

If manure is applied to meet the entire nitrogen requirements of a corn crop, there will usually be more P and K applied than the crop will remove, and soil test levels will increase. For liquid manure, an application goal of two-thirds to three-quarters of the nitrogen requirements for a corn crop is a reasonable compromise. The high carbon content in the bedding materials of solid manure makes the release of nitrogen much less predictable. Due to difficulty in uniform application for both solid and liquid manure, starter fertilizer is still recommended unless soil test results indicate that there will be no economic response to additional fertilizer.

Take into account residual nitrogen from legume crops when determining additional nitrogen needs from manure or fertilizer (see Table 9-7, Adjustment of Nitrogen Requirement, Where Crops Containing Legumes Are Plowed Down). Apply manure to cereal crops, soybeans or canola with caution, since too high a rate will increase the potential for lodging. For summer application to standing crops such as corn or forages, keep rates below 45,000 L/ha (4,000 gal/acre) or 55-65 kg/ha (50-60 lb/acre) ammonium nitrogen. Complete application to forages as soon as possible after harvest to avoid wheel track damage to new growth and potential nitrogen burn to new leaf growth. Older forage stands with higher grass content will benefit most from the manure nitrogen. Do not apply concentrated manures with high ammonium-nitrogen levels (e.g., liquid layer poultry or concentrated finisher hog manure) into standing crops.

Soil compaction is a problem for many growers and is the main reason that late summer or early fall manure application is so popular. Compaction leads to poor drainage and decreased aeration. The best way to reduce or avoid soil compaction from manure application is to spread manure when the soil is dry. Loads should stay below 4.5 tonnes (5 tons) per axle. Spring spreading is often carried out on fields where soils are too wet, and it is not unusual for strips of stunted crops to reveal the location of wheel traffic from application equipment.

Manure and No-Till

Manure is still one of the factors that make livestock farmers think twice about no-till systems. When manure is utilized in a no-till system, there has to be a compromise - some tillage or some loss of nutrients from manure.

A few points to consider when applying manure in a no-till system:

  • What is the goal for the manure applied? Is the organic matter from manure more important, or are the nutrients the focal point? If nutrients, especially nitrogen, are the important feature, decide which is more important: limited pre-planned tillage or some loss of nitrogen.
  • Manure type will influence how much nitrogen is potentially lost. Solid manure has a smaller percentage as ammonium nitrogen, therefore less total nitrogen will be lost. The higher organic nitrogen component is less available but releases nitrogen longer.
  • Where manure is surface applied, a majority of the ammonium portion of the manure will be lost. Rain (i.e., 12 mm gentle infiltrating) shortly after application will incorporate some of the ammonium.
  • A manure analysis is important.
  • Plan manure application well and consider crop rotation, especially in a no-till system where nutrients are not incorporated through tillage.
  • Manure applied after wheat or spring cereal harvest is the best option. Shallow tillage with a disc when soils are dry will help incorporate cereal straw and manure and could also incorporate cover crop seed. Minimal tillage will not disturb earthworm channels, and nitrogen will help with straw breakdown.
  • Apply manure to corn when soils are dry to avoid rutting and compaction. Consider side-dress applications to standing corn.
Table 9-14. Average Nutrient (N, P, K) Removal by Common Field Crops
Grains, Oilseeds

Removal
Kg/tonne (lb/bushel)

N2 P205 K20
Grain corn
11.5-18
(0.65-1.0)
6.6-7.9
(0.37-0.44)
4.6-5.2
(0.26-0.30)
Soybeans
62-67
(3.7-4.0)
13-15
(0.80-0.88)
23.3
(1.4)
Winter wheat (grain only)
19-21
(1.15-1.25)
9.1-10.4
(0.55-0.63)
6.0
(0.36)
Winter wheat (grain + straw)1
31-34
(1.9-2.1)
11-12
(0.68-0.75)
21-34
(1.25-2.0)
Barley (grain only)
18-23
(0.87-1.1)
8.0
(0.40)
5.3-7.2
(0.25-0.35)
Barley (grain + straw)
26-31
(1.2-1.5)
10-1.4
(0.5-0.6)
21-31
(1.0-1.5)
Oat (grain only)
18-24
(0.63-0.80)
7.5
(0.25)
5.8
(0.19)
Oat (grain + straw)
27-34
(0.9-1.5)
12.4
(0.42)
35-43
(1.2-0.5)
Winter rye
(grain only)
19-22
(1.1-1.2)
6.1-8.2
(0.3-0.5)
6.25
(0.35)
Winter rye
(grain + straw)
30
(1.7)
10-15
(0.6-0.8)
18-43
(1.0-2.4)
Dry beans
42
(2.5)
14
(0.83)
14
(0.83)
Canola
40-44
(2.0-2.2)
22-27
(1.1-1.3)
11-13
(0.55-0.67)

Source: Based on Ontario data where possible and general North American data where local data was insufficient.
Forage crop data from Agri-Food Laboratories, Guelph. (1990-95).

1 The range of P and K in cereal straw and dry hay will be reduced (leached) if heavy or frequent rainfall occurs while the material is in windrows in the field.
2 Soybeans, dry beans and forage legumes receive most of their nitrogen from the air.

Silage/Forage Crops

Removal in DM3
Kg/tonne (lb/ton)

N4 P205 K20
Corn Silage
11-15
(22-30)
4.6-6.8
(9.3-14)
8.3-15
(17-30)
Legume haylage
27-37
(53-73)
5.3-7.9
(11-16)
22-35
(45-71)
Mixed haylage
23-34
(46-68)
5.2-7.8
(10-16)
22-35
(45-71)
Grass haylage
16-27
(32-55)
4.9-7.8
(9.8-16)
20-36
(41-72)
Legume hay
22-33
(45-66)
5.2-8.0
(10-16)
21-35
(41-70)
Mixed hay
17-27
(34-55)
5.0-0.2
(10-14)
17-30
(34-59)
Grass hay (1st cut)
13-23
(26-45)
4.4-7.0
(8.8-14)
14-28
(28-56)
Mixed hay (2nd cut)5
25-36
(51-72)
5.7-7.8
(11-16)
20-32
(40-64)

Source: Based on Ontario data where possible and general North American data where local data was insufficient.
Forage crop data from Agri-Food Laboratories, Guelph. (1990-95).

3 To convert from "as harvested" to "dry matter yield," multiply the as-harvested yield by the dry matter content of the crop (e.g., 25T corn silage x 40% DM (60% moisture) = DM yield of 10T)
4 The range of N removal is large, because hay is harvested at a wide range of protein levels. Generally, higher protein means lower yield.
5 2nd cut generally has a higher legume content.

  • Manure applied ahead of soybean planting is an option where varieties are chosen with some resistance to white mould.
  • Liquid manure applied to forages is a good option. Apply manure as soon as possible after harvest, before re-growth. Application to older grass-alfalfa stands will give the largest nutrient benefit.
  • Avoid applying liquid manure to snow-covered perennial forages, since ice can form under the manure, resulting in increased winterkill.
  • A nutrient analysis is important, regardless of which crop the manure is applied to, so that commercial fertilizer application can be balanced with what was provided in the manure.
  • Too high a rate of surface applied manure can lead to slower soil warm-up in spring or sealing of soil. Calibrate application equipment to ensure an accurate rate.

Calibrating Application Equipment

Calibrating manure application equipment is essential. Several methods can be used to measure spreading rates. Weighing a load of manure and measuring the area that load covers is one method of estimating the rate of application. Weigh solid manure by placing plastic sheets on the ground and liquid manure by using straight-walled pails for measuring depth of application. Consider overlap, especially in irrigation systems. Table 9-15, Calibrating Manure Spreaders, gives an estimate of application rates, while Table 9-16, Densities of Different Types of Manure, distinguishes between the densities of different types of manure. For further detail, visit the OMAFRA website at www.ontario.ca/crops.

Table 9-15. Calibrating Manure Spreaders
Solid Manure Calibration1 Liquid Manure Calibration2
kg of Manure Application Rate Depth of Manure in Pail Application Rate
(per sheet) t/ha3 in. mm L/ha Imp. U.S.
gal/acre
0.5
3.6
1/10
2.5
25,000
2,225
2,675
0.9
7.2
1/8
3.2
32,000
2,850
3,420
1.4
10.8
1/4
6.4
64,000
5,520
6,845
1.8
14.3
4/10
10
100,000
8,900
10,690
2.3
17.9
1/2
12.7
127,000
11,305
13,580
3.2
25.1
6/10
15.0
150,000
13,355
16,040
4.5
35.8
3/4
19.1
191,000
17,000
20,420
6.8
53.8
1
25.4
254,000
22,610
27,160

1 Using a 122 cm x 102 cm sheet (40 in. x 48 in. plastic feedbag).
2 Using a straight-walled pail.
3 Tons per acre = tonnes per hectare x 0.45.

Environmental Concerns With Manure

Using manure to meet but not exceed crop nutrient needs will help minimize nutrient losses to the environment. Take additional care to avoid the movement of manure into streams from erosion, surface and tile runoff. Contamination of the environment is prohibited under the Environmental Protection Act, the Ontario Water Resources Act, and the federal Fisheries Act. In addition, there are specific requirements for manure application under the Nutrient Management Act and Regulation 267/03. See the most recent updates of the regulation, or contact an OMAFRA Nutrient Management Specialist, for more details.

Application to fields with steep slopes or impermeable soils can cause manure runoff when application rates are too high. For some soil types, several applications at lower rates may be necessary. Spreading manure in the winter and early spring is not recommended because of the potential for runoff to surface water and nutrient accumulations in water-ponded areas. Although winter application should not be part of a nutrient management plan, there are some mild spells where field application accompanied by immediate incorporation is possible. In years when winter spreading may be necessary, take care to select fields with the lowest risk of runoff to surface water.

 

Table 9-16. Densities of Different Types of Manure
Manure Type
Weight per Cubic Metre Weight per Cubic Foot Weight per Litre Weight per Bushel
Liquid
1,000 kg
62 lb
1.0 kg
80 lb
Semi-solid
960 kg
60 lb
0.9 kg
76 lb
Thick solid
800 kg
50 lb
0.8 kg
64 lb
Light solid
400 kg

25 lb

0.4 kg
30 lb

1 bushel = 1.25 cubic feet


Rain can cause organic nitrogen to wash into streams if manure has been applied to unprotected cropland. Phosphorus attached to soil particles can be carried to streams by soil erosion. Conservation practices can reduce the chances of nutrients polluting waterways.

Do not apply manure near watercourses. Runoff potential is influenced by field slope and soil texture. Flow in tile drains can become contaminated if manure enters a catchbasin or travels through soil cracks to the tiles. To minimize the risk of contaminated tile flow, apply at low rates when the tiles are not running, or lightly till the field before manure application to break any cracks or worm holes.

Applications of nutrients contained in manure or fertilizer in excess of crop requirements can result in contamination of groundwater, particularly on shallow soils over bedrock, soils with a water table close to the surface or very sandy soils where leaching is a concern. Groundwater contamination can occur by mass flow through cracks and holes to groundwater or through leaching of nitrates through the soil. Contamination can also occur if manure seeps directly into inadequately protected water wells. Manure should not be applied within 15 m (50 ft) of drilled wells, 30 m (100 ft) of dug wells or 100 m (330 ft) from a municipal well (Nutrient Management Regulations).

Large livestock operations on small land bases pose special challenges. To avoid over-application of nutrients, especially on fields near the barn, complete a nutrient management plan. It may be necessary to sign agreements with neighbouring farms to ensure the availability of fields for proper manure spreading.

Detailed information about maximum application rates and setbacks from surface water or water wells can be found in the NMAN software or OMAFRA Publication 818, Nutrient Management Workbook, available at www.ontario.ca/crops.

Nitrogen Risk Mitigation

The nitrogen cycle, with its many forms of nitrogen, is a complicated process that is influenced by many factors including weather, soil and physical, chemical and biological processes. Use the optimum amount of nitrogen, keeping in perspective that any nitrogen not used has the potential to leach below the root zone, volatilize into the atmosphere or denitrify (potentially to nitrous oxide - a greenhouse gas).

Nitrate that could potentially leach out of the rooting zone includes nitrogen that is applied in excess of crop removal and nitrogen from manure or biosolids applied during the non-growing season (late summer or fall). In Ontario, most of the drainage to groundwater occurs during the late fall to early spring period, when precipitation exceeds evaporation. On sandy, well-drained soils, much of the nitrate present in the fall could be leached into groundwater if drainage occurs. On heavier soils, more of the loss will be through denitrification. Minimizing the amount of soil nitrate present in the fall will reduce both types of loss.

Management practices to reduce the risk of nitrate losses include:

  • growing cover crops whenever manure is applied in late summer or early fall
  • timing nitrogen applications close to crop nitrogen uptake
  • matching total nitrogen applications to crop requirements

Phosphorus Risk Assessment

The risk of surface water contamination by phosphorus may be increased at higher soil test phosphorus levels. However, since phosphorus binds tightly to soil particles, the movement of soil from a field by erosion is also a major factor in determining the risk of surface-water contamination. Because of this, the risk of surface-water contamination by phosphorus cannot be based on a soil-test phosphorus level alone.

The risk of phosphorus contamination to surface water increases when soil test results indicate that no additional phosphorus is required to achieve maximum economic yield, but manure nutrients will still be applied. Phosphorus in surface-water sources increases eutrophication or aquatic plant growth, which leads to oxygen fluctuations and decreased ability for the water source to support aquatic life. To address the environmental risk of additional phosphorus application when soil test levels are adequate, a phosphorus index has been developed. The phosphorus index results in wider phosphorus-free buffers adjacent to water courses when there is a significant risk of nutrient/soil runoff and when phosphorus fertility levels are also high.

The phosphorus index considers:

  • soil erosion potential
  • water runoff potential
  • phosphorus soil fertility levels
  • fertilizer and manure application method and rate

For more information on phosphorus risk assessment, see the OMAFRA Factsheet, Determining The Phosphorus Index for a Field, Order No. 05-067, Publication 818, Nutrient Management Workbook, the NMAN software, or visit the website at www.ontario.ca/crops.

Biosolids and Residuals Use on Agricultural Land

Biosolids are nutrient-rich, processed organic materials derived from municipal wastewater treatment processes. They usually contain mineral and organic nitrogen, phosphorus, potash, organic matter and micronutrients such as zinc, magnesium and copper. The use of biosolids as part of a farm nutrient management package can reduce the demand for commercial fertilizers, improve soil fertility and enhance soil structure, moisture retention and permeability. Biosolids are ideal for crops such as corn, soybeans, cereals and forage crops.

Residuals include pulp-and-paper-mill fibre residuals, grain processing by-products and many other organic-based wastes, as well as some inorganic materials such as lime rejects from the sugar-processing industry. Each type of waste has unique characteristics that have the potential to benefit soil quality and/or crop production. Some may have limitations, e.g., sewage biosolids are very low in potassium. Be informed about the nutrient content, availability and possible negative impacts of biosolids and residuals use.

Biosolids and residuals land application is regulated under Part V of the Environmental Protection Act. The use of biosolids and residuals on agricultural land is regulated by the Ontario Ministry of the Environment. The Guidelines for the Utilization of Biosolids and Other Wastes on Agricultural Land, March 1996, sets out the guidelines related to biosolids and residuals quality, the application site criteria and the application of these materials on agricultural land. A Certificate of Approval is required before land application of any regulated waste material can occur. When properly used, biosolids and residuals can provide a valuable supplementation to a farm nutrient management program.

 

Table 9-17. Fertilizer Materials - Primary Nutrients
Nitrogen Materials Form % Nitrogen (N) Salt Index1
Ammonium nitrate
dry
30 to 34
15.3
Calcium ammonium nitrate
dry
27
15.3
Urea
dry
45 to 46
8.1
Ammonium sulfate
dry
21
16.3
Urea-ammonium nitrate
liquid
28
11.3
Anhydrous ammonia
liquid2
82
2.9

 

 
Phosphate Materials Form % Phosphate
(P2O5)
Salt Index1
Single superphosphate
dry
20
2.0
Triple superphosphate
dry
44 to 46
1.1
Monoammonium phosphate
dry
48 to 52
2.0
Diammonium phosphate (18-46-0)
dry
46
2.3
Ammonium polyphosphate (10-34-0)
liquid
34
2.3

 

 
Potash Materials Form % Potash
(K2O)
Salt Index1
Muriate of ptoash
dry
60 to 62
9.7
Sulfate of potash
dry
50
4.3
Sulfate of potash magnesia
(11% Mg)
dry
22
9.9
Potassium nitrate (13-0-44)
dry
44
6.1

1 Expressed per unit (100 lb) of nutrient.
2 Liquid under pressure.


For more information:
Toll Free: 1-877-424-1300
E-mail: ag.info.omafra@ontario.ca
Author: OMAFRA Staff
Creation Date: 13 May 2009
Last Reviewed: 15 September 2009