Field Crop Production
Understanding the Basics

Crop Rotation and Cover Crops

Crop Rotation

Rotating crops is a best management practice because:

• It reduces the risk of crop disease
• It reduces the population of pests specific to one crop
• It will increase the yields from a crop grown as part of a rotation compared to continuous cropping
• It can reduce soil erosion and run-off
• It spreads the workload for planting and harvesting over a longer time period as seasons vary with each crop
• It can complement each crop under rotation. For example, growing legumes provides nitrogen for non-legumes. And, alternating crops that successfully compete with weeds will reduce pressure on crops that do not
• By increasing crop yields and reducing inputs, profits on the combined crops can be higher
• Growers can stagger planting and field operations to avoid time pressures
• Special features of the farm can be taken into account, such as water resources, the nearness to markets and processing plants, special skills and labour availability.

Crop rotations can increase net returns.

At the same time, there are few precautions that should be taken:

• Planting times may conflict with critical phases of other crops such as weed control or an application of fertilizer that will boost yields
• New management skills may be needed
• Problems in one crop may make it difficult to manage another effectively.

The yields of corn and soybeans will improve if they are rotated with each other. By including a cereal in the rotation, yields and erosion control are improved. Adding a forage hay crop to the rotation improves yields and soil conditions even further.

If you are a cash cropper and cannot find land to put into forages, see if you can make a deal with a livestock producing neighbour. That way, you have a market for the forage grown and get the benefits in your rotation.

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Nutrient Management

Plants need 20 different nutrients for growth and seed production. Some are required in very small amounts while others make up the largest part of the plant. The most common elements in plant tissue (carbon, hydrogen, and oxygen) come from the air and water. Nutrients like calcium, magnesium and sulphur are common in Ontario soils; although they are used by plants in fairly large amounts, they are not usually considered in fertilizer programs.

Primary nutrients (nitrogen, phosphorus, and potassium) are the elements that most often have to be increased for crop growth. Plants use all three in large quantities. These elements make up the largest part of the farmer's fertilizer bill.

Micronutrients are used by plants in tiny amounts. They should be added when the plant shows signs of deficiency or when a soil test shows they are necessary.

Special Considerations for Manure

In most of Ontario, manure is applied to large areas of farmland. Manure is a valuable resource that contains all nutrients. Properly managed, it can supply nutrient requirements and add organic matter to the soil. However, excessive rates that exceed crop needs are hazardous to the environment. They increase the risk of nutrients escaping into surface and groundwater.

Tractor-mounted manure injection into high residue corn.

Best Management Practices for Nutrient Management

• Match nutrient requirements to crop needs and soil test levels. If a certain crop does not require much of a nutrient, don't overapply it. For example, if legumes do not need nitrogen, don't feed it to them. Put them into a rotation to benefit other crops that follow. Recognize that excess nutrients are potential pollutants.
• Include the contributions from previous crops and manure when deciding how much commercial fertilizer is needed.
• Complete regular soil tests for phosphorus, potassium and pH. Test for nitrogen when growing corn.
• Reduce soil erosion to eliminate phosphorus and organic matter losses.
• Maintain organic matter levels with manure, cover crops and residue to help cycle nutrients.

Pest Management

Pest management includes the control of plants, insects or diseases that compete with a crop and restrict its growth. The intent of best management practices is to prevent problems by using crop rotation and maintaining good soil fertility and structure. After all, a healthy, well-fed plant is best able to fight off pests.

Weed control aims to reduce nuisance plants to the point where the cost of damage to potential yield is less than the cost of control.

It is necessary to be balanced in your approach. Best management practices reduce the use of pesticides to the absolute minimum for your tillage system.

Some ways to reduce pesticide use are:

• Grow crops aggressively to compete with weeds.
• Use cover crops and companion crops as biological weed control.
• Scout fields for weed problems carefully and regularly.
• Rotate your crops.
• Rotate the pesticide family.
• Keep accurate records.
• Use tillage to control weeds.
• Band herbicide over the row.
• Use herbicides applied after crop emergence rather than soil-applied ones.
• Consider the economic threshold of control.
• Keep in mind that weeds appearing late in the season do not reduce yields as much.
• Avoid rescue treatments.
• Evaluate weed control.

Working Herbicides into Soil Requires Extra Management

Some herbicides are more effective if incorporated. This also reduces loss to run-off because the herbicide is placed below the soil surface. When you are incorporating herbicide, it's important to spray onto an even surface so that distribution is even. A rough surface may concentrate herbicide in valleys and clear it from ridges as shown in the diagram (below). Read the product label carefully to know what type of incorporation is required. Some heribicides (Treflans and Edge) are immobile in the soil. While this is good for the environment, it becomes very important to thoroughly mix the soil so that herbicides are at the proper depth. Sprayed pesticide only goes half as deep as the depth of tillage on the first pass.

Apply pre-plant incorporated herbicides to level fields.

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Field Planning and Records

Planning what will happen in a field and then recording the details are important in evaluating your practices. Records help establish the conditions that led to success but they are particularly important if something goes wrong. Looking back at your notes may help determine what caused the problem. Working from memory alone does not provide enough information for useable answers.

Records for each field should include:

• All applications of pesticides, fertilizers and manure.
• The variety of seed used.
• Include both rates and dates of operations.
• Record weather conditions when doing field operations.
• Note yields and crop quality.

Evaluate the success of your management and compare your results to research programs. There may be further improvements that you haven't considered.

A field record book can be seen on the Soil and Crop Improvement Association website.

Available in Published Version of Field Crop Production

• Crop Rotation and Cover Crops
  • Common Crops and Their Pros and Cons in Rotation
  • Cover Crops - Benefits, Using Cover Crops
• Nutrient Management
  • The Dynamics of Soil and Fertility - Organic Matter
  • Soil Testing
  • Maximum Economic vs. Environmental Yields
  • Fertilizer Types and Application Technology - Chart
  • Fertilizer Placement - How and Why - Broadcast, Banded
• Pest Management
  • Ways to Reduce Pesticide Use
  • How Likely Are My Pesticides to Move?
  • Factors in Pesticide Losses - Chart
  • Keep Pesticides on Target
  • Loss Potential of Some Common Agricultural Chemicals - Chart
    

Related Links

• Ontario Soil and Crop Improvement Association

| Introduction | Understanding the Basics | Approaching Change | Tillage Options | Non-tillage Options |
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