M.S. Level Student
Southern Illinois University Carbondale
Advised by Dr. Amir Sadeghpour
Assessing Fall Applied Phosphorus Sources and Wheat Cover Crop on the Following Soybean Performance
Growers often maintain soil test P (STP) using ammonium phosphate fertilizers, such as diammonium phosphate (DAP, 18-46-0) or monoammonium phosphate (MAP, 11-52-0) and employ fall application to avoid competition for time and wet field conditions, both prevalent in the spring. However, fall application of N with these P fertilizers presents a risk of N loss over the fallow period. One source that could minimize N loss during the fallow period is triple super phosphate (TSP; 0-46-0). This experiment evaluates wheat (Triticum aestivum L.) cover crop use of fall applied P sources and the following soybean (Glycine max L.) yield and yield component in rotation to evaluate response of soybean to wheat as a cover crop and P management in the fall. The trial had three P sources (DAP, MAP, and TSP) applied to supply 200 lb/acre P2O5 and a no-P control. These four treatments will be crossed with two levels of wheat cover crop (no cover and 2M seeds/acre) for a total of eight unique treatments (4 P source X 2 cover crop) replicated five times using a complete randomized block design. We will present the results on both wheat and soybean at the ISA conference.