Soil Management and Fertilizer Use:
Adjustments to Fertilizer Recommendations
(Legumes and Manure)

Excerpt from Agronomy Guide for Field Crops (Chapter 2)

Order OMAFRA Publication 811: Agronomy Guide for Field Crops

Table of Contents

1. Introduction
2. Adjustments to Legumes Plowed Down
   • Adjustment of Nitrogen Requirement Where Crops Containing Legumes Are Plowed Down - Table 2-15
3. Adjustments for Manure Application
   • The Value of Manure
   • Nutrient Management Plans
   • Average Amounts of Dry Matter, Nitrogen and Available Phosphate and Potash for Different Types of Organic Nutrient Sources - Table 2-16 (Metric) (Imperial)
   • Estimating Nutrients Available to the Crop From Average Values
   • Factors Affecting Availability of Manure Nitrogen to Crops
   • Estimate of Available Nitrogen (as a Proportion of Total Nitrogen) - Table 2-17
   • Manure Analysis
   • Predicting and Managing Nutrient Losses From Manure
   • Approximate Ammonium-Nitrogen Levels in Different Manure Types - Table 2-18
   • Estimated Percentage of Ammonium-Nitrogen Lost Due to Weather and Soil Conditions - Table 2-19(a)
   • Estimated Percentage of Ammonium-Nitrogen Lost Due to Weather and Soil Conditions - Table 2-19(b)
4. Long-term Value of Manure
5. Crop Requirements
   • Estimated Percentage of Organic Nitrogen Available in Year of Application - Table 2-20
   • Average Nutrient (N, P, K) Removal by Common Field Crops - Table 2-21
   • Calibrating Spreaders
   • Calibrating Manure Spreaders - Table 2-22
   • Densities of Different Types of Manure - Table 2-23
6. Environmental Concerns With Manure
7. Slope and Soil Texture Impact on Application Rate - Table 2-24
8. Determining Minimum Separation Distance From Watercourses - Table 2-25
   • Nitrogen Risk Assessment
   • Phosphorus Risk Assessment
   • Biosolids and Residuals Use on Agricultural Land
9. Updates on Soil Management and Fertilizer Use: Adjustments to Fertilizer Recommendations (Legumes and Manure)
10. Related Links...

Introduction

The general fertilizer recommendations in this book apply to situations where no organic sources of nutrients have been applied to the field. If manure or biosolids are applied to the land, or if legumes are plowed down, fertilizer rates should be reduced to adjust for the nutrients applied in the organic form.

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Adjustment for Legumes Plowed Down

When sod containing perennial legumes such as alfalfa, birdsfoot trefoil and clover are plowed under, they supply an appreciable amount of nitrogen to the following crop. Table 2-15, Adjustment of Nitrogen Requirement Where Crops Containing Legumes Are Plowed Down, shows reductions that should be made in nitrogen fertilizer applications to crops following sod containing legumes.

¹Applies where the legume stand is thick and over 40 cm (16 in.) high
²For all corps other than corn. For adjustments to corn fertilizer requirements, see Table 3-19. General Recommended Nitrogen Rates for Corn

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Adjustments for Manure Application

A large number of Ontario farms produce livestock, generating over 33 million tonnes of manure. Proper management of the nutrients from manure is essential for optimum economic benefit to the farmer with minimal impacts on the environment.|

The Value of Manure

The value of manure in crop production is often underestimated. 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.

¹Price based on average commercial fertilizer costs in 2001.

The equivalent amount of commercial fertilizer can be calculated using Table 2-16. Average Amounts of Dry Matter, Nitrogen and Available Phosphate and Potash for Different Types of Organic Nutrient Sources, and Table 2-17. Estimate of Available Nitrogen (as a Proportion of Total Nitrogen). At the sample prices for commercial fertilizer shown in this chart, the approximate value of the manure is $222/ha ($90/ac) assuming that all nutrients are needed by the crop.

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Nutrient Management Plans

*See Updates section below. A nutrient management plan matches the nutrients available in manure, from cover crops, in commercial fertilizer and in the soil to the nutrients required by the crop (see Table 2-16. Average Amounts of Dry Matter, Nitrogen and Available Phosphate and Potash for Different Types of Organic Nutrient Sources). Analysis of nutrients contained in the manure, along with soil test results and crop requirements, help to determine the application rate and additional commercial fertilizer requirements.

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

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Source: OMAFRA NMAN 2001 Software

¹Approximate value based on spring-applied manure, immediately incorporated, and on N-P205-K20 value/lb of $0.40-0.35-0.17.
²Includes some yard runoff.
³Includes milkhouse wastes
*See Updates section below.

Source: OMAFRA NMAN 2001 Software

¹Approximate value based on spring-applied manure, immediately incorporated, and on N-P205-K20 value/lb of $0.40-0.35-0.17.
²Includes some yard runoff.
³Includes milkhouse wastes.
*See Updates section below.

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Estimating Nutrients Available to the Crop From Average Values

The best way of determining the amount of each nutrient from manure is to analyze a sample. Unfortunately, this is not always possible, as in the case of a new barn. In this case, average values will provide an estimate of the nutrients available to the crop, when the nitrogen availability is adjusted for the time of application.

Table 2-16. Average Amounts of Dry Matter, Nitrogen and Available Phosphate and Potash for Different Types of Organic Nutrient Sources, provides the average results from manure analyses at the five accredited labs in Ontario over the past 6 years. Phosphate and potash values are reported as nutrients available to replace fertilizer nutrients. Nitrogen is reported as total N and ammonium N. The ammonium nitrogen in manure is chemically the same form of nitrogen as in many mineral fertilizers and is immediately available to the crop. Unfortunately, the ammonium form is also subject to loss by volatilization if not incorporated immediately. The balance of the nitrogen in manure is in the organic form, which becomes available to crops gradually as the organic compounds break down to release ammonium. The availability of manure N to the crop depends on the proportion of ammonium and organic N, the timing of application and the timing of incorporation.

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Factors Affecting Availability of Manure Nitrogen to Crops

Manure from different farming systems contains varying proportions of organic and ammonium nitrogen. Liquid manure contains a higher proportion of the nitrogen in the ammonium form than solid manure. 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 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.

Source: Beauchamp et al., University of Guelph, 2000

¹Available N = Total Manure N applied x proportion available (assumes a spring-planted crop).
²Accounts for ammonia loss to atmosphere and mineralization of organic N. For manure incorporated within 3 days, use: (incorporated value + non-incorporated value)÷2
*See Updates section below.

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Organic nitrogen is not available to the crop until it has been mineralized to the ammonium form by microbial action. This process occurs most quickly with warm temperatures and adequate moisture, and will almost stop when soil temperatures drop towards freezing. Nitrogen from solid manure applied just before planting may not be available in time to meet the requirements of the crop.

Ammonium nitrogen is further converted to nitrate by microbial action in the soil. Unlike ammonium, which will stick to soil particles, the nitrate ion can move freely with soil water.

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

Table 2-17. Estimate of Available Nitrogen (as a Proportion of Total Nitrogen), shows the proportion of available nitrogen from different materials depending on the time of application. 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.

This table 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 surface of the soil, 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 2-18. Approximate Ammonium-Nitrogen Levels in Different Manure Types) and the availability of the organic nitrogen. Urea has been included as an example of how fertilizer nitrogen availability compares with that of manure.

The values in Table 2-16. Average Amounts of Dry Matter, Nitrogen and Available Phosphate and Potash for Different Types of Organic Nutrient Sources, and Table 2-17. Estimate of Available Nitrogen (as a Proportion of Total Nitrogen), above, along with the manure application rates, can be used to estimate the amount of nitrogen available to the crop from manure applications at different timings. *See Updates section below. For example, if solid broiler manure is applied at 9 t/ha (4 t/ac) in spring on cereal residue, with no incorporation, the nitrogen available to the crop from manure would be 73.5 kg/ha (65.5 lb/ac). This is calculated by multiplying the total nitrogen content of the manure (22.5 kg/tonne or 54.6 lb/ton) by the application rate (9 t/ha or 4 t/ac), giving a total nitrogen application of 244.6 kg/ha (218.4 lb/ac). The availability factor for a spring preplant application is 0.3, and this, multiplied by the total N application, gives an available N of 73.4 kg/ha (65.5 lb/ac) (244.6 x 0.3 = 73.4 kg/ha or 218.4 x 0.3 = 65.5 lb/ac).

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Manure Analysis

*See Updates section below. Manure analysis is necessary because the quantities of nutrients contained in manure 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. Fertilizer adjustments based on a manure analysis will be much more accurate than those based on average values.

Above-average levels of nitrogen and/or phosphorus in manure may be an indication that dietary protein or phosphorus is being fed at higher than required levels. 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 manure analysis is available from several laboratories in Ontario. An analysis should be performed after complete agitation or thorough mixing each time the storage is emptied (i.e., spring and fall). After several analyses, a trend in results should become evident, and sampling can be limited to major changes in ration or other management factors.

When sending a sample to the lab, fill a plastic jar (about 1-litre capacity) half-full, cover and 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 send back 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 given. The relation between total and available phosphorus and potash is the same for all application timings. When reading the report, note carefully whether you are reading total nutrient contents or available nutrients.

For more information on interpreting a manure analysis, see Appendix D, Calculating Available Nutrients from a Manure Analysis.

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Predicting and Managing 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 2-18. Approximate Ammonium-Nitrogen Levels in Different Manure Types, Approximate Ammonium-Nitrogen Levels in Different Manure Types, right. The organic nitrogen component is available over time as the organic matter breaks down, similar to a slow-release nitrogen fertilizer. About 20% to 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.

Source: OMAFRA NMAN 2001 Software

Ammonium-nitrogen is immediately available to a growing crop but is also most 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 during sunny, high-temperature days when soils are dry; losses are lowest when conditions are overcast and cold, when soils are moist or during rainy periods. Table 2-19. 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 late fall-applied manure, the losses appear low since cooler temperatures minimize 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 the section Nitrogen Risk Assessment.

Adapted from Beauchamp, University of Guelph, 1995.

Adapted from Beauchamp, University of Guelph, 1995.
*See Updates section below.

Table 2-20, 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.*See Updates section below.

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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. Manures also contribute other plant nutrients and organic matter to soil that may be of some long-term value.*See Updates section below.

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 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. The N soil test for corn or barley can be used to assess available nitrogen in succeeding years following application. The soil test for P and K should be used to measure residual phosphorus and potassium from manure applications.

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Crop Requirements

Soil test results and yield goals will determine the maximum economic application rate and/or additional fertilizer requirements. Often soil test levels on livestock farms indicate that soil fertility levels are adequate or high and do not require additional fertility. One alternative to allow for manure application is to determine the nutrients removed by a crop and then match phosphorus and/or nitrogen from manure to determine an application rate that will not build soil test to excessive levels. Table 2-21, Average Nutrient (N, P, K) Removal by Common Field Crops, will help determine the average nutrient removal for various crops.

Source: Potash and Phosphate Institute,1997.
*See Updates section below.

Crop Removal = Base Value x (Estimated Yield ÷ Base Yield)

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. With solid manure, because of the high carbon content of the bedding material, the release of nitrogen is much less predictable. Due to difficulty in even application for both solid and liquid manure, starter fertilizer is still recommended unless soil test results indicate that no additional nutrients are needed.

Residual nitrogen from legume crops should be taken into account when determining additional nitrogen needs from manure or fertilizer (see Table 2-15, Adjustment of Nitrogen Requirement Where Crops Containing Legumes Are Plowed Down). Manure applications to cereal crops, soybeans or canola should be done with caution, since too high a rate will increase the incidence of lodging. For summer application to standing crops such as corn or forages, rates should be kept below 45,000 L/ha (4,000 gal/ac) or 55-65 kg/ha (50-60 lb/ac) ammonium nitrogen. Application to forages should be completed as soon as possible after harvest to avoid potential nitrogen burn to new leaf growth. Older forage stands with higher grass content will benefit most from the manure nitrogen. Concentrated manures with high ammonium-nitrogen levels (for example, manure from covered storages or manure from swine barns with wet-dry feeders) should be avoided for application into standing crops.

Soil compaction is a problem for many growers. It leads to, among other things, poor drainage and decreased aeration. The best way to reduce or avoid soil compaction is to spread manure when the soil is dry. Keep loads below 4.5 tonnes (5 tons) per axle. Consider these points when selecting spreading equipment and deciding when to spread manure (i.e., summer vs. spring vs. fall application). Spring spreading is often carried out on fields that are too wet, and it is not unusual for strips of stunted crops to show where the wheel tracks were.

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Calibrating Spreaders

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. Solid manure can be weighed by placing plastic sheets on the ground and liquid manure by using straight-walled pails for measuring depth of application. Overlap should also be considered, especially in irrigation systems.*See Updates section below. Table 2-22, Calibrating Manure Spreaders, gives an estimate of application rates while Table 2-23, Densities of Different Types of Manure, distinguishes between the densities of different types of manure. The OMAFRA Factsheet How to Calibrate Your Manure Spreader, Order No. 97-003, is available as a reference.

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

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Environmental Concerns With Manure

Using manure to meet but not exceed crop nutrient needs will help minimize nutrient losses to the environment. However, take care to avoid the movement of manure into streams from erosion, surface and tile runoff.

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. Table 2-24, Slope and Soil Texture Impact on Application Rate, will help determine the maximum rates for single applications of manure on your field as it relates to runoff potential.

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Table 2-24. Slope and Soil Texture Impact on Application Rate

Source: Best Management Practices: Nutrient Management Practices, Order No. BMP 05, OMAFRA and Agriculture Canada, 1998. Watch for an updated version.

The runoff potential can also be used to determine the minimum separation distance from streams and other watercourses.

Spreading manure in the winter and early spring is not recommended because of the potential for runoff to surface water. The fate of the first meltwater following manure application determines whether this will be a problem or not. Do not incorporate this practice into a nutrient management plan. In years when winter spreading may be necessary, take care to select fields where there is no risk of runoff to surface water. *See Updates section below.

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.

Manure should not be applied near watercourses.*See Updates section below. Runoff potential is influenced by field slope and soil texture. Table 2-25, Determining Minimum Separation Distance From Watercourses, right, can be used to determine the runoff potential to establish a minimum separation distance. In a no-till system that includes a 3 m (10 ft) wide buffer strip along the watercourse, the separation distance can be reduced to 9 m (30 ft) for liquid manure and 4.5 m (15 ft) for solid manure.

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Source: Best Management Practices: Nutrient Management Practices, Order No. BMP 05, OMAFRA and Agriculture Canada, 1998. Watch for an updated version.

Flow in tile drains can become contaminated if manure enters a catchbasin or travels through soil cracks to the tiles. With liquid manure, maintain a 9 m (30 ft) buffer around a catchbasin or surface inlet (4.5 m or 15 ft with solid manure).

Apply liquid manure onto tiled fields using caution. If field tiles are running, liquid manure can travel through macropores and contaminate surface water sources. If there is any history of tile contamination via soil cracks or macropores, tillage prior to application and/or monitoring of tile outlets is strongly recommended.

Applications of nutrients 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, or 30 m (100 ft) of dug wells.

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

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Nitrogen Risk Assessment

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, however, 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).

The movement of nitrogen to groundwater sources has also become an important issue in many communities. Groundwater and aquifer vulnerability studies are being conducted in many locations across Ontario with results that indicate that agricultural impact can be significant. As a result, a nitrogen index is being developed to help minimize the risk of nitrogen leaching below the root zone, especially in coarse-textured and shallow-to-bedrock soils. Management practices that include cover crops with late summer and early fall manure applications as well as timing nitrogen applications as close to crop nitrogen requirements and/or reduced total nitrogen applications are all methods that help reduce potential nitrogen loss.

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 in the summer or fall. In Ontario, most of the drainage to groundwater occurs during late fall to early spring, 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 nitrate present in the soil in the fall will reduce both types of loss.*See Updates section below.

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
• reduced total nitrogen applications

For future information on nitrogen risk assessment, once developed, refer to the OMAFRA Web site at www.omafra.gov.on.ca/english.

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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.

*See Updates section below. When soil test results indicate that no additional phosphorus is required to achieve maximum economic yield, but manure nutrients will still be applied (Excessive), the risk of phosphorus contamination to surface water increases. 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.

For more information on phosphorus risk assessment, see Appendix C, Phosphorus Index.

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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 byproducts 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 that producers should be aware of. For example, a papermill residual that is low in nitrogen and high in carbon may temporarily tie up soil nitrogen when applied. This has the potential to cause a nitrogen deficiency in the crop. Producers should be provided with information on the nutrient content and 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.

*See Updates section below.

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Updates on Soil Management and Fertilizer Use: Adjustments to fertilizer Recommendations (Legumes and Manure)

Addition to Nutrient Management Plans section - "Farms generating more than 300 Nutrient Units that must complete a nutrient management plan must use the NMAN software or Nutrient Management Workbook."

Addition to Table 2-16 footnote - "These average nutrient contents are provided for information only. Refer to the NMAN Nutrient Management Workbook and/or the NMAN software for the most up-to-date information. All regulated nutrient management plans must sample and analyze manure at least once for every NMP renewal."

Addition to Table 2-17, Estimate of Available Nitrogen footnote - "Manure nutrient contents for use in nutrient management plans should be calculated using the NMAN software or Nutrient Management Workbook."

Addition to The Values in Table 2-16, and Table 2-17, along with the manure application rates... - "Manure nutrient contents for use in nutrient management plans should be calculated using the NMAN software or Nutrient Management Workbook."

Addition to Manure Analysis section - "Farms generating more than 300 Nutrient Units that must complete a nutrient management plan must collect manure samples at least once for every NMP renewal."

Addition to Long-Term Value of Manure section - "Nutrient management plans must account for nutrients from previous manure applications."

Addition to Table 2-19 and Table 2-21 footnote - "Manure nutrient contents for use in nutrient management plans should be determined from analysis, or by using the NMAN software or Nutrient Management Workbook."

Addition to Calibrating Spreaders section - "Use of high-trajectory irrigation guns for the application of liquid manure is not allowed on farms that are required to complete a nutrient management plan, and is being phased out for all farms by March 31, 2005."

Addition to Environmental Concerns with Manure section:

"Winter application of manure is allowed with some limitations. Regulation 267/03, and the Nutrient Management Protocol, for full details." and;

Addition to Nitrogen Risk Assessment section - "Manure applications in late summer or early fall on AA, A or B Hydrologic Soil Groups require a cover crop to be established, or the N index completed. Fall application rates cannot exceed what would be applied in the spring unless an N index calculation is completed."

Addition to Phosphorus Risk Assessment section - "Manure applied to soils with soil test values in excess of 30 mg/L phosphorus must complete a phosphorus index to determine separation distance from surface water. Refer to NMAN software or Nutrient Management Workbook."

Addition to Biosolids and Residuals Use on Agricultural Land section - "Farms that are required to complete a nutrient management plan are limited to applying no more than agronomic rates of nitrogen and phosphorus, in addition to the listed limits."

OMAFRA Publication 811: Agronomy Guide for Field Crops Table of Variance

OMAFRA Factsheet How to Calibrate Your Manure Spreader, Order No. 97-003, is no longer available.

Related links...

• Soil Management
• Soil Fertility & Crop Nutrition

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