Agronomy: Soybean Best Management Practices

Are you following the best management practices for conservation and nutrient loss reduction?

Illinois farmers, the fertilizer industry and government agencies, along with agronomists and CCAs, are teaming up across the state to do their part in implementing the Illinois Nutrient Loss Reduction Strategy (INLRS) to help reduce surface water contamination and greenhouse gas emissions. While nitrogen fertilizer is not commonly applied for soybeans, the soybean crop uses a large amount of nitrogen (N), and management practices that reduce N loss from soybean crops are important to the INLRS.

The goal is nutrient loss reduction, not nutrient use reduction. Supplying adequate nutrients to maintain crop yields is essential, and is part of the worldwide effort to adopt 4R Nutrient Stewardship—applying the Right Source at the Right Rate in the Right Place at the Right Time.


The 4R system is being promoted throughout the world to demonstrate to the non-farming community that we are following best management practices (BMPs) to reduce environmental problems.

4R Nutrient Stewardship addresses the agronomics of nutrient use efficiency, the economics of maintaining yields and avoiding excess inputs, environmental issues such as nutrient contamination which leads to hypoxia in the Gulf of Mexico and social issues such as interference from recreational water uses like boating and fishing. The image below shows the location of farms and cities within the Mississippi River Basin and the location of the hypoxic zone just beyond the mouth of the Mississippi River. By 2025, the goal of the INLRS is a 15 percent reduction in the contribution of nitrate from Illinois farms.


Nutrient pollution from the Mississippi River Basin fuels the Gulf of Mexico Hypoxic Zone. How can 4R Nutrient Management help? Image by NOAA's Environmental Visualization Lab.

Current 4R management practices provide adequate crop nutrition and reduce nutrient losses. These practices also focus on reducing nitrogen (N) and phosphorus (P) contamination of water resources as well as reducing N loss to the atmosphere as NOx greenhouse gases.

Soybeans fix N2 from the air using nodulating bacteria. Nitrogen from the soil is provided as carry-over from previous crops, along with mineralized N from crop residues and soil organic matter. Supplemental N should be applied only if your soybeans are producing extraordinary high yields and soil N is lacking.

Using 4R management, soybean producers can do their part to implement the INLRS and protect our natural resources. The INLRS will help protect our ability to use essential crop nutrients in the future, without burdensome regulations. For example, nutrients can be trapped by cover crops, then released as the cover crop residue decomposes, hopefully at the right time for the soybean crop to utilize them. Cover crops also help prevent soil erosion.

Site-specific precision farming technology supports 4R Nutrient Stewardship, and provides tools to justify and document production practices—what we do and why. This depends upon complete production records which track the business health of our farms as well. Inputs should be applied with variable-rate systems where appropriate and all inputs and harvest records should be geo-referenced.

  • Geo-referenced crop records should include:
    • Soil test records; geo-referenced
    • Yield monitor data
    • As-applied maps for all seed, fertilizer and pesticides
    • Remote sensing imagery (satellite, aerial or AUV)
  • Scouting records from weekly field visits to each field
    • Notes of observations on crop condition and stage of growth
    • Geo-referenced photos of any problem areas (use a digital camera with GPS)
  • Weather records—rainfall and max/min temperature at least

These records help farmers be better environmental stewards and better businessmen. They provide the basis for better-informed management decisions. Be a part of the solution—help to implement the  Illinois Nutrient Loss Reduction Strategy.

Harold Reetz is a Certified Crop Adviser working as an agronomy consultant in Monticello, Illinois. His areas of expertise include high-yield crop production, precision farming technology, 4R plant nutrient management systems and conservation systems. 

Harold Reetz



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