Saturday, 15 July 2006
155-97

Effects of New Nitrogen Technologies and Rates on Corn in Southern Illinois.

Stephen A. Ebelhar1, Carl. D Hart1, and Jorge D. Hernandez2. (1) Univ of Illinois, Dixon Springs Agric. Res. Cnt., Simpson, IL 62985, (2) Southern Illinois Univ, S. Illinois Univ Mail Code 4415, Dept of Plant, Soil and Ag Systems, Carbondale, IL 62901-4415

Problems with the availability of Ammonium Nitrate (AN) and anhydrous ammonia fertilizers in United States corn production has increased the demand for urea and Urea-Ammonium Nitrate (UAN) solution. These replacement fertilizers have problems with volatilization and perhaps even denitrification when surface applied (in no-till systems) or lightly incorporated with secondary tillage at time of planting. ESN (a polymer coated granular urea) and granular Super Urea are new fertilizer technologies designed to reduce Nitrogen (N) losses from agricultural systems and therefore improve nitrogen use efficiency. A comparison of N sources and N rates was conducted at two locations (the University of Illinois Dixon Springs Agricultural Center [DSAC] and the Southern Illinois University Belleville Research Center [BRC]) for three years, 2003-05. Treatments consisted of five N sources granular urea, ESN, UAN solution, granular AN, and granular Super Urea. Each N source was preplant surface broadcast applied and incorporated with a secondary tillage tool within two hours under a Conventional Tillage (CT) system or left on the surface with a No-Tillage (NT) system. These treatments were applied to corn following soybeans in conventional tillage, but to corn after corn in the no-tillage system. These treatments were compared to a sidedress injected UAN application, which may be considered a Best Management Practice (BMP) treatment. Nitrogen rates of 0, 67, 134, 201 and 268 kg N per hectare were used with each of the above source treatments. Both urea and UAN had significant problems when either surface broadcast (NT) or surface broadcast and incorporated (CT). When rainfall was very high (ex. Belleville, 2003), ESN, Super Urea and UAN sidedress injected were all superior. These superior treatments were usually equal, and seldom resulted in lower yields than other treatments across locations and years. The UAN broadcast and urea treatments were consistently inferior, while the ESN, Super Urea, and AN broadcast and UAN sidedress injected were consistently superior N sources. These results are less consistent with no-tillage continuous corn.

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