Effect of Tillage and Soil Phosphorus Target Level On Corn Yield.

A sufficiency correction strategy for recommending phosphorus (P) for corn (Zea mays) with a critical level (15 ppm Bray #1) determined by field research is the basis for Nebraska P recommendations. A strict interpretation of this approach means waiting for soils to go below the critical level and may ignore special cases where corn may respond with higher soiltest levels. Three sites were established in Nebraska in 2011 to determine the effect of three soiltest Bray #1 P levels (15, 25, and 35 ppm), crop removal P applications, and a no P control. In addition, each site has a tillage factor (no-till vs disk). Two sites are irrigated, and one site is calcareous. Effect on soil test levels and yields will be discussed.