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The University of Maryland currently maintains three "long-term" field sites where soil test phosphorus (P) is monitored on plots receiving no P following manure applications at five rates to achieve a gradient of soil test P concentrations. Through the use of advanced technologies, the goal of this project is to understand the behavior of P during drawdown by grain and forage crop rotations when no additional P is applied, specifically the shift in soil P pools under a long term P drawdown scenario. Further analysis of archived soils collected from this project will lead to a better understanding of long-term transformations of P in soils as P is depleted.
Many agricultural soils throughout Maryland, and the greater Delmarva Peninsula, have high concentrations of P due to a long-term history of manure applications at or exceeding rates designed to meed crop nitrogen needs. Maryland's P-based nutrient management standards restrict manure applications on soils with soil test P, thus, manure may not be applied where P loss potential is high or where soil test P concentrations exceed 500 UM-FIV. Unfortunately, in fields where only grains are harvested, it is estimated that it will take decades to reduce P concentrations to a point where manure can again be used at P-based rates to fertilize grain crops.
This research is being conducted by Dr. Nicole Fiorellino and Dr. Louis Thorne of the University of Maryland, along with Dr. Amy Shober of the University of Delaware.
The Maryland Grain Producers are pleased to fund this ongoing phosphorus research with $8,373 for 2022!
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