Infosheet #16  Nutrient Management in Growing Crops

Table of Contents

• Introduction
• Soil Testing
  • 16-1 Timing and number of soil samples
  • 16-2 Record keeping
• Use of Fertilizer
  • 16-3 Amount of nutrient
  • 16-4 Adjustment to amount of fertilizer needed when using legumes or cover crops
  • 16-5 Adjustment to amount of fertilizer needed when using manure or biosolids
• Application of Fertilizer
  • 16-6 Application system - inorganic sources
  • 16-7 Application system - organic sources
  • 16-8 Timing of nitrogen application
  • 16-9 Nutrient loading during the rotation
  • 16-10 Potential for nutrient losses through leaching or runoff

Introduction

This infosheet provides background to Worksheet #16 of the Environmental Farm Plan Workbook. It outlines options you could adopt to address problem areas in your operation. In most cases you'll need more information before implementation: please refer to the resource materials listed in the infosheet and consult OMAFRA Environmental Farm Plan (EFP) Technical Advisors.

All options are classed as Actions, Compensating Factors or Monitoring.

Actions address the areas of concern identified, and will change the rating to (3) or Best (4). Compensating Factors are alternatives that will adequately address the concerns, but will not change the rating in the EFP Worksheets. Monitoring is an alternative only in special circumstances and is expalined in the Infosheet when and how it can be used.

At the request of the Ontario Farm Environmental Coalition, consisting of Ontario Federation of Agriculture, Christian Farmers Federation of Ontario, AGCare, and the Ontario Farm Animal Council, the following people contributed to the development of Infosheet #16:

Keid Reid, OMAFRA (Chair)
Mark Stauffer, Potash & Phosphate Institute
Elwin Vince, Ontario Soil and Crop Improvement Association (OSCIA)
Jim Eddie, MOEE

Technical Editing Committee:
Brent Kennedy, OMAFRA
Jim Myslik, OMAFRA
Bob Stone, OMAFRA

The following people contributed to the revision (2004) of Infosheet #16:

Keith Reid, OMAFRA (Chair)
Christoph Kessel, OMAFRA
Jonathan Watchurst, OSCIA, EFP Program Representative

Technical Editing Committee:
H.J.Smith, OMAFRA
Jim Myslik, OMAFRA
Bob Stone, OMAFRA

OMAFRA = Ontario Ministry of Agriculture, Food and Rural Affairs

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Soil Testing

Issue: 16-1 Timing and number of soil samples

Soil testing is the only way to determine whether the soil in your fields is deficient, adequate or excessive in fertility. A good test contains enough cores to represent the natural variability present in the field, and does not try to represent a field which is too large. Tests must be taken often to track any changes in soil fertility.

What can you do?

Option - Action

Start a regular soil testing program:

• the actual sampling should be done by yourself, an employee, or by a crop consultant or fertilizer dealer
• make sure the samples are analyzed at an accredited lab
• many farmers find it works well to take samples at a certain point in the rotation, e.g., on wheat stubble in a corn, bean, wheat rotation
• a minimum of one soil core should be taken per acre - maximum area represented by one sample of 50 acres (testing smaller areas gives better reliability)
• fields are tested at least every five years, preferably every three years
• grid sampling or sampling according to yield variability could identify problem areas within a field.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Agronomy Guide for Field Crops, OMAFRA Publication 811
• Best Management Practices Book: Nutrient Management, Order No. BMP 07, pp. 38-42

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Issue: 16-2Record keeping

Record keeping is an integral part of tracking fertility performance. A proper nutrient management program will gradually build your soils from low to moderate soil test levels, and they should level out there. Excessive soil test levels, or rapidly increasing or decreasing levels, indicate either a problem with your nutrient management program, or a problem with your test. Failing to keep records means that you have no idea whether your fertilizer management program is meeting its goals or not.

Sampling at the same place in the rotation will make it easier to remember what fields to sample, and eliminate one source of variation in your soil samples.

What can you do?

Option - Action

Set up a system to record the results of the soil tests:

• records should include: date, crop, previous crop, yield, field identification, nutrient test results and name of lab
• set up a schedule for routinely sampling the fields.
• recording soil test values for each field on a graph will make trends over time immediately apparent.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Best Management Practices Book: Nutrient Management, Order No. BMP 07, page 47
• Field Pocketbook, OMAFRA Publication 820, a record keeping system and resource for field crop management
• Ontario Soil and Crop Improvement Association produces an excellent record booklet called the Soil Fact Book, which is available from most OMAFRA offices
• Check with the agricultural industry for availability of crop/soils record keeping books/ computer programs.

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Use of Fertilizer

Issue: 16-3Amount of nutrient

A soil test is only useful if it is used to determine individual field fertilizer application rates. Using provincial research to guide your actions should ensure that the rate recommended is appropriate to provincial conditions.

Adding unnecessary fertilizer will not increase crop yields (lowering profitability), and increases the risk of environmental contamination. In some cases, excess fertilizer can decrease crop yield or quality.

What can you do?

Option - Action

Use the fertilizer recommendations from an accredited Ontario lab, or from the various OMAFRA publications with "Production Recommendations":

• a soil test is required to get fertilizer recommendations
• if you have difficulty interpreting your soil test results or a soil test is not available, contact your local OMAFRA office to determine the appropriate fertilizer rate.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Agronomy Guide for Field Crops, OMAFRA Publication 811
• Fruit Production Recommendations, OMAFRA Publication 363
• Vegetable Production Recommendations, OMAFRA Publication 363
• Best Management Practices Book: Nutrient Management, Order No. BMP 05, pp. 43, 64-66

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Issue: 16-4Adjustment to amount of fertilizer needed when using legumes or cover crops

Forage legumes can supply a large amount of nitrogen (N) for crop production. Ignoring this source of N is not only wasteful and lowers profitability, but increases the risk of environmental contamination. By using legumes to full nutrient advantage, you can save money on fertilizer. These crops also improve soil structure and moisture-holding capacity, allowing more efficient use of the native fertility of the soil.

What can you do?

Option - Action

Realistically assess the stand of forage legume, and adjust your nitrogen fertilizers according to the tables in the various OMAFRA publications with "Production Recommendations":

• a full stand of perennial legumes (alfalfa, trefoil or clover, if left in the field for more than one year) is anything greater than 12 plants per square foot. A 50% stand is six plants per square foot, and this would receive the same nitrogen allowance as a full stand (can provide 110 kg/ha of N to the next crop)
• a vigorous stand of legume cover crop (killed during the seeding year) can provide 45 kg/ha of N to the next crop
• reduce the allowance if the stand is thin, or if the top growth is less than 45 cm
• a soil nitrate test taken just before side-dress can help to assess the nitrogen contribution from a legume crop. Remember that the amount of soil nitrate can vary greatly within a field, so use the test as a guideline only.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Agronomy Guide for Field Crops, OMAFRA Publication 811, pg 36

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Issue: 16-5 Adjustment to amount of fertilizer needed when using manure or biosolids

Manure or biosolids (including sewage biosolids) can supply large amounts of nutrients for crop production. By using these to full advantage, you can save money on fertilizer. These additions also improve soil structure and moisture-holding capacity, allowing more efficient use of the native fertility of the soil. Using these sources of materials, but ignoring the amounts of nutrients in them is not only wasteful, it increases the risk of environmental contamination.

What can you do?

Option - Action

Reduce the amount of fertilizer applied by the amount of available nutrient added by manure or biosolids:

• obtain an analysis for biosolids applied to your land and reduce your fertilizer rates accordingly
• get your manure analyzed to determine the nutrient content of the manure and accurately determine how much you are applying
• send an appropriately sized sample to a lab for testing of N, P and K<
• a manure analysis from the previous year will be a good guide to the nutrient content of the manure - liquid manure, in particular, will be fairly constant from year to year unless your management has changed
• weigh at least a few loads so you know how much is going on your fields
• figure out the total nutrients you are applying and reduce your fertilizer rates accordingly
• concentrate on applying manure to crops with a high nutrient demand, or crops on fields with low soil test values, rather than to the fields closest to the barn.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Best Management Practices Book:Nutrient Management, Order No. BMP 07, pp. 31-37

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Application of Fertilizer

Issue: 16-6 Application system - inorganic sources

Fertilizers that are left on the soil surface are subject to losses to the air (especially nitrogen), or to surface water through runoff. Incorporating fertilizer whenever possible will minimize these losses, increasing the efficiency of fertilizer use and decreasing the risk of environmental contamination.

What can you do?

Option #1 - Action

• Incorporate nutrients where possible:
• incorporate broadcast fertilizers as soon as possible after application, preferably within 24 hours
• in reduced tillage systems, band as many nutrients as possible
• starter fertilizers banded at planting
• nitrogen side-dressed between the rows of corn and other row crops.

Option #2 - Action

Where possible, limit broadcast applications of fertilizer to level fields:

• avoid broadcasting fertilizers on floodplains, steeply sloping fields, or near watercourses.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Agronomy Guide for Field Crops, OMAFRA Publication 811
• Best Management Practices Book: Nutrient Management, Order No. BMP 07, pp. 51-63

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Issue: 16-7Application system - organic sources

Manure or biosolids that are left on the soil surface are subject to losses to the air (especially nitrogen), or to surface water through runoff. Incorporating manure or biosolids whenever possible will minimize these losses, increasing the efficiency of manure or biosolid use and decreasing the risk of environmental contamination.

What can you do?

Option #1 - Action

Incorporate nutrients where possible:

• incorporate broadcast manure/biosolids as soon as possible after application, preferably within 24 hours
• inject liquid manure/biosolids below the soil surface.

Option #2 - Action

Where possible, limit broadcast applications of manure/biosolids to level fields:

• avoid broadcasting manure/biosolids on floodplains
• do not apply manure/biosolids on steeply sloping fields (>9% slope) or near watercourses.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Agronomy Guide for Field Crops, OMAFRA Publication 811
• Best Management Practices Book: Nutrient Management, Order No. BMP 07, pp. 51-63
• Nutrient Management Act 2002, Ontario Regulation 267/03 as amended

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Issue: 16-8Timing of nitrogen application

Nitrogen is the nutrient with the greatest risk of loss (volatilization or leaching) from a cropping system. Applying nitrogen when the crop needs it will increase the efficiency of the nitrogen fertilizer, as well as reducing the potential for environmental contamination. Side-dress or top-dress applications of nitrogen also allow you to assess the condition of the crop, and adjust your nitrogen applications to reflect any

reductions in yield potential. Applying nitrogen when the crop is not able to absorb it only wastes time and money, and can result in the direct pollution of the environment.

What can you do?

Option #1 - Action

Side-dress most of the nitrogen applied to corn and row crops with high nitrogen requirements:

• apply a small amount as a starter and side-dress the balance
• adjust side-dress rates for crop conditions.

Option #2 - Action

Top-dress nitrogen on cereals and pure grasses just before they begin to grow quickly.

Option #3 - Action

Apply N less than two weeks prior to planting.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Agronomy Guide for Field Crops, OMAFRA Publication 811
• Best Management Practices Book: Nutrient Management, Order No. BMP 07, pp. 17, 52

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Issue: 16-9Nutrient loading during the rotation

As the total nutrient application to any given field increases, the risk of environmental contamination from that field also increases. This is particularly true when nutrients are applied in excess of crop uptake, or when bare soil in the field (either from wide row spacing, or in the time between crops) allows erosion or leaching. Applying too little fertilizer may also be detrimental if it restricts the growth of the crop and results in less ground cover.

What can you do?

Option - Action

Alternate crops which use high rates of fertilizer with crops that use residual soil fertility:

• for example, where soybeans follow corn in the rotation, the corn will respond to applied fertilizer, while the soybeans can utilize the residual fertilizer from the corn crop
• use soil tests to optimize the amount of fertilizer applied to any given crop.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611
• Best Management Practices Book: Nutrient Management, Order No. BMP 07, pp. 11-23, 38-47
• Agronomy Guide for Field Crops, OMAFRA Publication 811

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Issue: 16-10Potential for nutrient losses through leaching or runoff

The risk of nutrient movement off a field is balanced by the amount of ground cover and root mass that is available to absorb the nutrients. The lowest risk of nutrient movement off a field will occur when there is a permanent sod (dense root network) receiving little or no fertilizer. (Obviously, this is not a viable agricultural system for everyone.) Any practice which increases the amount of ground cover or root mass will help you achieve lower risk of nutrient loss from the field.

What can you do?

Option - Action

Utilize cover crops when a crop is not growing, or increase the proportion of sod crops in the rotation:

• add some solid seeded crops into your rotation
• use soil tests to optimize the amount of fertilizer applied to any given crop.

For More Information:

• Soil Fertility Handbook, OMAFRA Publication 611

Infosheet Table of Contents

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