Resumen de Optimizing application rate of nitrogen, phosphorus and cattle manure in wheat production: An approach to determine optimum scenario using response-surface methodology
Optimal application rates of inorganic nitrogen (N), phosphorus (P) and cattle manure were estimated using Response Surface Methodology (RSM). A Central Composite Design (CCD) was conducted at field level during 2012-13 and 2013-14 growing seasons. The applied levels of N were 0, 150 and 300 kg N ha-1 in form of urea. The levels used for P fertilizer were 0, 100 and 200 kg ha-1 (P2O5) and for cattle manure were 0, 15 and 30 t ha-1. Both seed yield (SY), biological yield (BY) were measured at harvest time. N loss (NL) and Agronomic N Use Efficiency (ANUE) were calculated based on other measurements. Increasing N and P rates up to 200 kg ha-1 increased SY. Optimization of N, P and manure application amount was based on economic, environmental and eco-environmental scenarios. Under economic scenario, using 145.4 kg ha-1 N, 200 kg ha-1 P and 18.4 t ha-1 manure resulted in 6500 kg ha-1 SY with ANUE of 10.49. For environmental scenario, by N application of 21.2 kg ha-1, no application of P and applying 16.3 t ha-1 manure, SY and ANUE of 3160 kg ha-1 and 9.08 were obtained, respectively. Using eco-environmental scenario, by applying 144.7 N and 34.3 kg ha-1 P, plus 30 t ha-1 manure, about 4031 kg ha-1 SY and a considerable high ANUE of 16.5 were recorded. The results of this study showed that the privilege of eco-environmental scenario compared to the other scenarios was mainly due to higher ANUE.
