Add more- that was the official extension recommendation for phosphorus fertilization for many decades. Phosphorus is tightly bound in most soils. This nutrient has a strong affinity for reactive groups on soil particles including iron, aluminum and calcium. In order to make sure plants had access to enough P, extension agents typically recommended applications well in excess of plant requirements. That paradigm had a sudden shift about 30 years ago when scientists realized that heavily loaded soils could release P in cases of erosion and even by movement through the soil profile. The era of excess P was born. New soil tests have been developed to measure excess P. New rules restricting use of P have been promulgated in many areas. This new paradigm does not typically recognize the importance of recycling P through use of residuals -based amendments. At about the same time, there has been a recognition of the limited P reserves for production of additional P fertilizers. Reuse of residuals can be the answer to both P saturated soils and low reserves of phosphorus ore. Residuals typically provide slow release P and increase the soils’ ability to bind P, and reduces the movement of water that leaches P. Also, in areas where excess P is an issue, other materials can be added to compost to help bind P, as a designer compost product.
Speakers: Sally Brown
Duration: 17 minutes
Credits: 0.5
Member Price: $30.00
Non-Member Price: $52.50
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USE.113-Paradigm shift: Changing Recommendations for Phosphorus Fertilization-AC22.USCC
