"If these acres were fallowed from last year, available nitrogen may be very high," Gelderman says. "However, if the acres being planted are recrop acres, then available nitrogen could be moderate or low. Nitrogen fertilizer costs have increased 20-30% over last year, so soil sampling for available nitrogen can be a real money saver. Knowing that additional nitrogen is needed also can help the producer make money on the extra yield gained."
Only a deep (0-2-ft.) nitrate-N test can show if nitrogen is adequate or if more is needed, Gelderman says. Soil tests allows a producer to maximize profits by putting high price fertilizer dollars on fields that need it and not wasting money on those that don't.
"This is also a good time of year to begin sampling those harvested small grain and silage fields," Gelderman says. "If there were areas of a field that didn't produce as well as others, sample these areas separately to determine if plant nutrients are the problem. In addition, soil sampling alfalfa and grass areas can be done at this time. Sampling now will take off the pressure after corn and soybean harvest to accomplish this task before fall tillage."
Tillage makes taking a good soil sample more difficult. An early snow may stop all field operations until spring and producers may lose the opportunity for planning how to use their limited fertilizer dollars, Gelderman says. Soil samples can be sent to the Soil Testing Lab, Box 2207A, SDSU, Brookings, SD, 57007. Contact: Ron Gelderman, (605) 688-4770