Effects of fully biodegradable film mulch on growth, yield and nitrogen utilization of maize

Objectives We investigated the effect of replacing plastic film with biodegradable film in maize production, as well as the suitable fertilizer input, to alleviate the residual plastic pollution in farmlands in northwest China.

Methods A 2-year field experiment with split plot design was conducted in Pingjipu farm, Ningxia Hui Autonomous Region in 2019 and 2020 The main factor (mulching film type) included biodegradable film (BF), ordinary film (OF) and un-mulched control (CK); the subplots (nitrogen application rate) included N rates of 0, 120, 240, 360 kg/hm². The growth and yield of maize were recorded, N use efficiency of maize and the degradation rate of BF was measured.

Results Compared with CK, BF treatment significantly improved the dry matter accumulation of maize by 10.82%, the maximum accumulation rate by 0.034 t/(hm²·d), and the time reaching maximum accumulation rate was 6.86 days earlier in BF, while the N uptake, N recovery rate and agronomy efficiency increased by 11.97%, 31.47%, and 26.20%. BF and OF treatments produced similar values for all the above indices. Multiple regression analysis showed that the maximum yield of maize under BF and OF treatments was 1.42×10⁴ and 1.43×10⁴ kg/hm², and the corresponding N rate was 285.61, and 284.44 kg/hm². At N 240 kg/hm², the yield was similar under BF and OF conditions. The two years average degradation rates of BF and OF were 40.65% and 2.17%, respectively. Both BF and OF treatments obtained the maximum economic gains under N240 treatment, although no significant difference existed between them.

Conclusions Fully biodegradable film mulching had similar growth and yield effect with plastic film mulching in a drip irrigated maize. Under both film mulch types, the maximum nitrogen absorption, utilization and economic benefit at N rate of 240 kg/hm² were recorded. Compared with ordinary plastic film, fully biodegradable film saves the investment of collecting residual film, so the total economic benefit is comparable with that of ordinary plastic film. Considering the additional environmental advantages, fully biodegradable plastic film should be promoted in spring maize production in northwest China.