Project title: Soil Test Phosphorous Target Levels for Corn

Principal investigators: Charles Shapiro, Richard Ferguson, Gary Hergert, Timothy Shaver, Charles Wortmann

Duration: 1990- Present

Funding: HATCH Funding; Nebraska Legislature

Contact:

Charles Shapiro Northeast Research and Extension Center, Haskell Agricultural Laboratory, UNL, 57905 866 Road, Concord, NE 68728-2828 (402) 584-2803, cshapiro1@unl.edu

Project description:

Response to applied P was evaluated in 34 high yield corn trials during 2002 to 2004.

In another study, the effect of soil test P levels on corn yield is being evaluated. The targeted levels of Bray-1 soil phosphorus are 15, 30 and 45 ppm. In addition a no-phosphorus control and an application of phosphorus at removal rates are included.  

Key results: Bray-1 P critical levels of 20 ppm for corn following corn and 15 ppm for corn following soybean were determined.

In the study with targeted Bray #1 P levels, yield has been slightly more with P applied at the removal rate (Bray-1 P = 24 ppm) compared with the Bray #1 P target of 15. Applying P for target levels of 30 and 45 ppm Bray-1 has been the least economical options.

Publications:

Wortmann, C.S., A.R. Dobermann, R.B. Ferguson, G.W. Hergert, C.A. Shapiro, D.D. Tarkalson, D. Walters. 2008. High yield corn response to applied phosphorus, potassium, and sulfur in Nebraska. Agron. J. 101 546-555.

Shapiro, C.A., R.B. Ferguson, G.W. Hergert, and C.S. Wortmann. 2009. Fertilizer suggestions for corn. University of Nebraska Extension EC 117.