How to use phosphorus wisely

Marilyn Thelen<thelen22@msu.edu>, Michigan State University Extension - April 28, 2015

Soil testing and applying phosphorous at agronomic rates is the first step in phosphorus management.

Phosphorus is an essential nutrient for healthy growth of plants, animals and even people. We all need some phosphorus to grow and thrive. Plants require phosphorus for photosynthesis, respiration, seed production, root growth and other critical plant functions. Animals and humans need it for proper bone and muscle growth, metabolism, reproduction and overall performance, according to “Understanding Soil Phosphorus” by the University of Wisconsin. So, phosphorus is good, even essential.

Problems arise when phosphorus is provided to the crop or livestock system in greater levels than required. When excessive application occurs, phosphorus may accumulate in the soil and exit the plant-soil system. At this point, phosphorus can become a water quality concern, causing excessive growth of algae and aquatic vegetation.

The first step for keeping phosphorus in the field and out of surface waters is to soil test and maintain phosphorus at a soil nutrient level that supports plant growth but does not accumulate excessively beyond optimal levels. Michigan State University Extension recommends soil testing fields every three to four years. Soil tests conducted by the MSU Soil and Plant Nutrient Laboratory provide a report to the producer with MSU recommendations for lime and fertilizer. Reports from other labs may easily be converted by using the MSU Fertilizer Recommendations Program. Keeping nutrient recommendations realistic means providing achievable crop yield goals. Realistic yield goals should be achievable 50 percent of the time.

Finally, any phosphorous that is added to the field through bio-solid or manure applications should be accounted for when determining how much inorganic phosphorus is required to achieve the recommended level.

Take the first step – soil test and apply at recommended rates!

For more information on nutrient management, visit the MSU Soil Fertility Research website.

This article was published by Michigan State University Extension. For more information, visit https://extension.msu.edu. To have a digest of information delivered straight to your email inbox, visit https://extension.msu.edu/newsletters. To contact an expert in your area, visit https://extension.msu.edu/experts, or call 888-MSUE4MI (888-678-3464).