Effects of plastic film mulching and straw mulching on wheat yield and nitrogen utilization during different precipitation years

Objectives Plastic film mulching and straw mulching are widely used in wheat production in northwest dryland area. We compared the effect of the two mulching methods under different precipitation years, to provide support for efficient and sustainable wheat production.

Methods A field experiment was conducted from 2012 to 2020 in dryland of Xianyang City, Shaanxi Province. According to the annual precipitation, there were three rainy years, one normal year and four dry years during the experimental period. Randomized complete block design was adopted for the study with four treatments: no-N application control, conventional mode, plastic film mulching and straw mulching. Except control, all the plots received N 150 kg/hm². The wheat grain yield, yield components, N uptake, and the N use efficiency were determined.

Results Compared to the conventional mode, plastic mulching and straw mulching increased wheat grain yields by 9.9% and 6.8%, 15.0% and 12.8%, 16.3% and 15.2%, 13.0% and 10.9% during the rainy, normal, dry years, and 8-year cumulative mean, respectively. Number of spikes increased by 15.1% and 10.9%, 4.4% and 13.2%, 3.3% and 8.7%, 9.0% and 10.4%, respectively. The aboveground N uptake increased by 14.2% and 15.4%, 2.1% and 5.8%, 6.4% and 8.5%, 9.6% and 11.5%, respectively. The grain N uptake was increased by 7.0% and 9.8%, 4.0% and 5.4%, 6.5% and 9.2%, 6.4% and 9.1%, respectively. The N apparent use efficiency was enhanced by 23.0% and 24.9%, 3.0% and 8.1%, 10.4% and 14.0%, 15.3% and 18.2%, respectively. The N agronomic efficiency increased by 20.4% and 13.8%, 25.1% and 21.5%, 34.5% and 31.8%, 26.2% and 21.9%, respectively. Compared with straw mulching in the 8-year study, the wheat grain yield of plastic film mulching increased by 0.9%‒2.9%, the N agronomic efficiency increased by 2.1%‒5.9%; compared with plastic film mulching, the aboveground N uptake of straw mulching increased by 1.0%‒3.6%, the grain N uptake increased by 1.4%‒2.7%, the N use efficiency increased by 1.5%‒4.9%. Compared to straw mulching, number of spikes with plastic film mulching increased by 3.9% during rainy years, and decreased by 1.2%‒7.8% during the normal and dry years.

Conclusions Regardless of the amount of precipitation, both the plastic film mulching and straw mulching had markedly and similarly improved water storage, moisture retention, wheat yield, and N utilization. By comprehensively considering the economic and environmental benefits, it is recommended to use straw mulching in sustainable wheat production.