by Dr. Clark Neely, Statewide Small Grains and Oilseed Extension Specialist, College Station, TX
Dr. Jake Mowrer, Statewide Soil Fertility Specialist, College Station, TX
Dr. Emi Kimura, Regional Extension Agronomist, Vernon, TX
Dr. Dennis Coker, Soil Fertility Program Specialist, College Station, TX
Russell Sutton, Assistant Research Scientist, Commerce, TX
Daniel Hathcoat, Small Grains Program Specialist, College Station
One of the foremost questions on many wheat producers’ minds this year is “Will I make any money on wheat?” While it is true wheat prices are down and many budgets are in the red, there are some steps that can be taken to improve the chances of staying in the black. One of those steps is soil sampling and crediting soil nutrients. In this article we will focus on nitrogen. Soil sampling is a basic, but proven technology that can reliably reduce fertilizer applications. There have been studies done in Texas on cotton, corn and sorghum showing the benefits of crediting soil nitrates, but little data on the amount or depth one can credit soil N for winter wheat in Texas. This credit can be accurately calculated through a deep profile soil test (up to 24”).
A study conducted in 2016-2017 showed no significant yield differences between the control (no crediting) and crediting down to 24” inches at all study sites (Figure 1). In fact, wheat yield did not respond to increasing nitrogen applications in two of the three sites. This, combined with additional nitrogen found at 36” and 48” depths suggests wheat will even utilize nitrogen from below 24”. Test weight was also the highest at all sites when crediting down to 24”.
Based on this information, producers could save a significant amount of fertilizer cost by soil sampling and crediting nitrate nitrogen already in the soil. There was approximately 21, 40, and 30 lb N/a in the top 24” of soil at Leonard, McGregor, and Vernon, respectively. Assuming nitrogen costs $0.34/lb, a producer would have saved between $714 and $1360 on a 100 acre field, minus the cost of soil sampling, which runs $10/sample for a routine analysis that includes nitrate nitrogen at the Texas A&M AgriLife Extension Service Soil, Water and Forage Testing Laboratory. If your previous crop was not harvested due to a crop failure (e.g., stand establishment issues or hail damage), which is often observed in the Rolling Plains, there is a high possibility that the N was not fully utilized by the crop and may still remain in the soil. Of course, a soil test is the only way to know if these savings are possible on your farm.
For more information on proper soil sampling please visit: http://varietytesting.tamu.edu/files/wheat/docs/fertility/Testing%20Your%20Soil%20-%20How%20to%20Collect%20and%20Send%20Samples.pdf.