Evaluation of New Nitrogen Fertilizer Technologies for Corn.

Farmers today are faced with escalating fertilizer prices, especially for nitrogen. Gains in nitrogen use efficiency (NUE) can help offset these prices. Nine different N sources were surface broadcast at four to five locations annually across the state of Illinois over a three year period.  These sources included 1) urea, 2) liquid urea-ammonium nitrate (UAN), 3) urea + agrotain®, 4) UAN + agrotain broadcast, 5) UAN + agrotainplus® (agrotain plus a nitrification inhibitor), 6) UAN + 10% v/v CaTs® (calcium thiosulfate), 7) SuperU® (urea with agrotain and a nitrification inhibitor), 8) ESN (polymer-coated urea), and 9) UAN sidedress injected.  All of the above treatments were applied at planting, except for the sidedress UAN injected treatment.  Treatments included each of the N sources above either incorporated or left on the surface under conventional tillage (CT), or left on the surface under no-tillage (NT) systems.  Nitrogen rates of 67, 134, 202 and 269 kg N per hectare were associated with each N source. The yield responses associated with N sources could be broken into wet locations (those with >30 cm rainfall over the 15 week period after fertilizer application) and dry locations (<30 cm). Nitrogen source effects were highly significant at the wet locations. The dry fertilizer products tended to do better than the liquid products.  There was a fair amount of N loss from surface applied urea or UAN, indicating volatilization losses, which was reduced significantly by the application of agrotain or superU.  Sidedress injection of UAN or application of ESN also significantly reduced N losses and increased yields. It appears that many of the N sources in this study may provide significant improvements in N use efficiency, especially during wet years.  These differences appear to more important with NT than CT, but more research is needed.