Analysis and Closing of the High-Production-Maize Yield Gap in the Semi-Arid Area of Northeast China

A mulched drip fertigation system is an effective way to improve maize yield, but at present, the efficiency of nutrient delivery and water use are generally low. Therefore, this study conducted optimization field experiments to identify the main factors limiting the delivery of water and fertilizer, including regulations on nitrogen (N) fertilizer, irrigation conditions, planting density and maize varieties, in the semi-arid area of Northeast China. As part of an effort to close the yield gap for maize, an optimized system (DS) for optimal crop, nutrient and water management was designed to improve the agronomic and economic performance of maize farming in the area. The application rate of N fertilizer was 240 kg ha-1; the base fertilizer was applied four times (once at the jointing stage, twice at the belling stage and once at the silking stage); the rates of application of phosphorus (P) and potassium (K) fertilizer were 90 kg P2O5 ha-1 and 90 kg K2O ha-1, respectively; the irrigation amount was 270 mm ha-1; the maize variety Fumin 985 was planted at a density of 80,000 plants ha-1 in DS; the grain yield of DS reached 13.8 Mg ha-1, 93% of the yield potential. DS yielded an economic benefit of 18,449 yuan ha-1, which was significantly higher than the economic benefit of 13,818 yuan ha-1 achieved under farmers' practices (FP). Furthermore, the utilization rates of N, P, K, and water were significantly improved under DS. In conclusion, DS increased production potential, with high efficiency in nutrient delivery and water use and low losses of nutrients and water. The crop, fertilizer, and water management of DS provided a technological system to simultaneously improve crop production and resource-use efficiency in the semi-arid area of Northeast China.