Optimizing N-Fertigation Scheduling to Miantain Yield and Mitigate Global Warming Potential of Winter Wheat Field in North China Plain

Abstract

Evaluating the impact of N-scheduling on crop production and GHG emissions is an important way of ensuring optimum nitrogen management on croplands. Limited results exist on compromising between reduced global warming potential (GWP) and improved grain yield (GY) to achieve an optimized N-scheduling for winter wheat fields under drip fertigation systems. A two-year field experiment was conducted to determine the effect of split nitrogen fertigation on GWP and wheat yield. Five levels of nitrogen schedule were applied using different percentages of basal and topdressing (fertigation) applications through a total of 240 kg ha-1 of nitrogen fertilizer (urea). The treatments were coded as N0-100, N25-75, N50-50, N75-25 and N100-0. The results revealed that the treatments significantly (p < 0.05) affected the GHG emissions, GWP, crop yield, and subsequently the greenhouse gas intensity (GHGI). Soil NO3ˉ-N and NH 4 + -N were found to be the most important factors affecting GHG emissions. Compared with N0-100 treatment, N50-50 was found to decrease GWP and increase GY by 12 ~ 23% and 9 ~ 10%, respectively. Cumulative CO2, CH4 and N2O emissions, GWP and GHGI were decreased in N50-50 treatment. Furthermore, a multi-objective decision method known as Rank Sum Ratio (RSR) suggested that N50-50 or N25-75 was the optimum N-fertigation schedule. However, the Technique for Order Preference by Similarity to Idea Solution (TOPSIS) specified that N50-50 provides the best results for minimized GWP at an acceptably high GY. Therefore, the N-scheduling (50:50) would be recommended for sustainable wheat production with minimum risk of global warming.