Effects of autumn mulching on water and fertilizer use efficiency and yield of spring maize in Western Liaoning Province

In order to examine the effects of autumn film mulching on water and nitrogen use efficiency of spring maize in semi-arid area, a field experiment was conducted in 2013-2015 for two consecutive years in National Agricultural Experimental Station for Agricultural Environment, and three mulching patterns were set up: plastic film mulching at autumn (film mulching begins after harvest in autumn, AM), plastic film mulching at spring (conventional growing season mulching, SM), and no film mulching (NM). Combined with 15N isotope tracer method, the characteristics of water and nitrogen utilization of spring corn mulched in autumn were analyzed. The precipitation during the growing period of spring maize was 310 and 249 mm in 2014 and 2015, respectively, which was lower than the historical average. During the experiments, maize was not irrigated. The aboveground dry matter of maize, biomass yield, grain yield, water consumption and water use efficiency were determined. The results showed that the AM treatment promoted maize growth. After the tasseling period, the aboveground dry matter of maize in the AM treatment was 8.7% and 4.5% higher than the treatments of SM and NM, respectively. The grain yields of AM treatment in 2014 and 2015 were 19% and 11% higher than the SM treatment and 14% and 75% higher than the NM treatment (P<0.05), but there was no significant difference on biomass yield between AM and SM (P>0.05) in the two consecutive years of relative drought. The AM treatment reduced the water consumption in the leisure period (P<0.05), the soil water storage in the sowing period increased by 35 mm on average compared with SM and NM treatments. The water consumptions of maize during tasseling and filling periods was significantly increased (P＜0.05). There were no significant difference in water use efficiency of grain yield and that of biomass yield of maize among the three treatments in 2014 (P>0.05). There was no significant difference in water use efficiency of grain yield and that of biomass yield of maize between AM and SM in 2015(P>0.05), but both were significantly higher than NM(P<0.05). The AM and SM treatments averagely increased the water use efficiency of grain yield and that of biomass yield of maize by 60% and 65% compared to NM in 2015. The AM treatment reduced the nitrogen fertilizer loss, and also reduced the nitrogen fertilizer residue in the soil compared with SM treatment, which improved the use efficiency of nitrogen fertilizer significantly in the current season and the following year (P<0.05). The cumulative nitrogen fertilizer use efficiency reached 50.5% in the two years, while those of SM and NM treatments were only 42.7% and 33.5% in the two years, respectively. However, the residual fertilizer nitrogen of AM treatment in the 0-100 cm soil layer was significantly higher than that of NM treatment (P<0.05). Therefore, the comprehensive analysis showed that autumn film mulching was an effective technical measure for improving the water and nitrogen fertilizer use efficiency and yield of spring maize in the semi-arid west of Liaoning province under the relatively dry years. Optimizing the application of nitrogen fertilizer can further enhance the value of this technology in regional agricultural development.