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Agronomic and environmental management of phosphorus

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Quick facts

  • Use conservation tillage systems to reduce the amount of soil lost by erosion.
  • Band or inject phosphate fertilizers and manure below the soil surface.
  • Monitor soil test levels for phosphorus. There’s no reason to build soil test levels above 20 parts per million (ppm) using the Bray test or 16 ppm using the Olsen test.

Managing phosphorus for crop production

Managing phosphorus inputs for crop production systems is a very important task, but it doesn’t have to be a complicated one.

Here, we’ll describe management practices and how they affect phosphorus losses.

Generally, management practices that reduce the potential for environmental contamination also help minimize costs:

  • Use conservation tillage systems to reduce the amount of soil lost by erosion.

  • Band or inject phosphate fertilizers and manure below the soil surface.

  • Monitor soil test levels for phosphorus. It’s not necessary to build these levels above 20 parts per million (ppm) using the Bray test or 16 ppm using the Olsen test.

Environmental impact

The relationships between nutrient management and environmental quality is an area of concern. In the late 1980s and early 1990s, people involved with agriculture focused their attention on the environmental impacts of nitrogen applied in fertilizers and manures.

More recently, attention has shifted to the effect of phosphorus management on water quality in lakes and rivers.

Ample evidence shows that algal growth in surface waters is directly related to concentrations of nitrogen and phosphorus. This is why the amount of phosphorus that enters surface waters has received special attention.

How to control phosphorus losses

Research efforts throughout the United States have focused on developing management practices to control the loss of phosphorus from the agricultural landscape.

In general, phosphorus losses are affected by:

  1. Crop grown.

  2. Tillage systems.

  3. Rate, time and method of applying inorganic and organic sources of phosphorus.

  4. Soil test level for phosphorus.

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Daniel E. Kaiser, Extension nutrient management specialist and Paulo Pagliari, Extension soil scientist

Acknowledgements

Partial funding for this publication was provided by the Metropolitan Council and the Minnesota Board of Water and Soil Resources.

Reviewed in 2018

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