Effect of wheat straw retention on light energy utilization and water production benefits of maize in inland irrigated region

The response of light energy utilization and production benefit of crops to straw return to soils usually is important for establishing highly efficient cropping systems and optimizing cultivation practices. It is also the theoretical basis for exploring the cost-saving and benefits-increasing crop production in arid inland irrigation area. A field experiment was carried out in a typically irrigated oasis region in 2009-2012 in the Hexi Corridor of China to determine the effects on light energy utilization and production benefit of maize of different treatments of wheat straw return to soil and different tillage operations. The tillage and wheat straw retention operations included (i) no tillage with straw standing (NTSS), in which no tillage was combined with 25 to 30 cm high wheat straw standing in the field after wheat harvesting in the previous fall; (ii) no tillage with straw covering (NTS), in which no tillage was combined with 25 to 30 cm long wheat straw evenly spread on the soil surface at wheat harvest in the previous fall; (iii) tillage with straw incorporation (TIS), in which 25 to 30 cm long wheat straw was incorporated into the soil through conventional deep tillage (30 cm) at wheat harvest in the previous fall; and (iv) conventional deep tillage without wheat straw retention (as control), in which conventional deep (30 cm) plow was done with wheat straw removed from the field. The results showed that compared with the control, wheat straw retention treatments reduced leaf area duration (LAI-D) of maize before the large bell mouth stage, however, increased LAI-D of maize after silking, which effectively delayed senescence. No tillage with straw standing and straw covering (NTSS and NTS) had the best effects on senescence delay among all treatments, and the total LAI-D increased by 11.2% to 14.5% under NTSS, 16.3% to 20.8% under NTS and 6.0% to 7.5% under TIS, respectively; specifically, the increase in LAI-D under NTS treatment was the highest. Wheat straw retention had the effect of improving light use efficiency of maize field, and NTS treatment had the highest increasing effect, whose light use efficiency was 5.3% to 11.8% higher than that of the control. The previous wheat straw retention was favorable to increase grain yield of maize, and NTS treatment had the best increasing effect of grain yield, boosted grain yield by 13.7% to 17.5% compared with the control. NTSS and NTS treatments reduced the production cost, while improved the net return and the input-output ratio. NTS treatment had the large increasing range, increased the net return and the input-output ratio by 22.2% to 35.5% (3 953 to 5 200 ￥·hm^-2) and 16.8% to 23.4%, respectively. Meanwhile, the water productivity and benefit per cubic meter water were improved by 13.7% to 17.5% and 25.6% to 33.1%, respectively. Based on the results therefore, no tillage with 25 cm to 30 cm long wheat straw covering over soil surface (NTS) was the most suitable straw return strategy, which can be used as the key technology for cost-saving and benefits-increasing maize production in arid inland irrigation area.