|Fall soil sampling for next year’s fertilizer decisions|
|Written by Gary W. Hergert, Charles Shapiro, Charles Wortmann, Richard Ferguson and Tim Shaver, Extension Soils Specialists, University of Nebraska – Lincoln|
|Friday, 28 October 2011 10:18|
Farmers have made excellent progress on this fall’s harvest and it’s time to think about next year’s fertilizer needs. The steady climb in fertilizer prices over the last year, the volatility in grain prices, and the precipitation and flooding extremes in some areas this past year make it even more important to do a good job of soil sampling this fall.
Recent rains across the state should provide great conditions for sampling after harvest (Figure 1).
This year has produced a range of precipitation. Varying corn yields due to N leaching, disease or weather damage produce variability in soil residual nitrate-N.
Because soil nitrate is mobile, soil sampling is the only reliable way to determine what is left in your soil. Soil samples for nitrate should be taken to at least a three-foot depth for next year’s corn crop. View soil management tools at http://cropwatch.unl.edu/web/soils.
Because pricing depends on an individual’s marketing plan, a range of fertilizer and corn prices can be used in the spreadsheet to look at the most profitable N recommendations. With corn in the $6 to $7 range and nitrogen in the $0.50 to $0.70 range, the recommended N rate for 200 bu/ac corn would range from 185 to 240 lb N per acre.
Nitrogen availability can be estimated based on when the manure was applied, the application rate, the concentrations of organic and ammonium-N, and the application method.
For more information on how this is determined, view the UNL webcast, Manure Application and Nutrient Management, at https://connect.extension.iastate.edu/p88906821/?launcher=false&fcsContent=true&pbMode=normal.
Concentrate on the nutrients that have been shown to produce yield increases. Products and nutrients that don’t have a research-based recommendation should be tested in small areas before being used extensively. FG
—University of Nebraska–Lincoln Cropwatch newsletter, October 2011
Figure 1 courtesy of High Plains Regional Climate Center. Figure 2 courtesy of Fertilizerworks.com, Basket Price. Figure 3 courtesy of Cleveland Research Company.