Improving Nitrogen Management In No-till Production Sysstem.

The large amount of surface residue left on the soil surface in no-tillage production systems can made nitrogen (N) management difficult. Surface broadcast applications of urea-containing fertilizers are subject to volatilization losses and are generally less efficient than ammonium nitrate. There are several products currently available for use with granular urea (46% N) and urea-ammonium nitrate solution (UAN) that have the ability to reduce or eliminated N losses. The objective of this study was to evaluate the effectiveness of several N-fertilizer additives and a slow-release polymer coated urea product in a no-tillage corn (Zea mays L.) production system. Studies were conducted at several locations to evaluate the effectiveness of nitrogen additives. Treatments at the Kansas site consisted of a control released polymer-coated urea product (PCU), acid polymer coated urea (AP), urea coated with a urease inhibitor, [N-(n-butyl) thiophosphoric triamide] (nBTPT) , untreated urea, UAN (28%) treated with nBTPT, UAN treated with nBTPT plus dicyandiamide (DCD), UAN treated with an acid polymer, untreated UAN, and ammonium nitrate. Each fertilizer treatment was applied at three rates of N (90, 180 and 270 kg ha-1). A no N check plot also was included. All fertilizer materials were broadcast on the soil surface after planting but before crop emergence. When averaged over the 3-years of the experiment, the treated fertilizer products yielded greater than untreated urea or UAN. This occurred regardless of applied N-rate. The additive treated products along with the time release-polymer coated urea yield the same as ammonium nitrate. There were no significant differences among additive products. The new acid polymer treated urea was as effective as nBTPT or nBTPT plus DCD.