Phosphorus Management for No-till Winter Wheat in Oklahoma.

Phosphorus deficiency in no-till winter wheat (Triticum aestivum L.) production can result in drastically reduced yields in north central Oklahoma. As a result, many producers are attempting to increase phosphorus application efficiency through the implementation of best management practices (BMP’s) such as soil sampling based fertility recommendations. Regardless of product source or application rate, phosphorus management may be confounded by the fact that current sampling methods and rate recommendations in Oklahoma were developed utilizing fields under intensive tillage practices. During the 2014 and 2015 winter growing seasons, nine on farm studies were established across North Central Oklahoma with varying soil type’s representative of the region to evaluate Oklahoma State University’s current soil sampling recommendations and soil test P recommendations. Site locations had initial Mehlich III extractable soil P concentrations ranging from 1 – 39 mg kg^-1 in the top 15.24 cm of soil at planting. Soil pH ranged from 4.6 to 6.8 across the nine locations. Grain test weight and moisture were not significantly affected by the addition of surface applied phosphorus. Wheat grain phosphorus concentrations were on average increased with the addition of phosphorus fertilizer but the response varied across treatment rates. Wheat grain yield was on average significantly increased by the addition of surface applied phosphorus fertilizer.