Effect of biodegradable film mulching on crop yield, soil microbial and enzymatic activities, and optimal levels of irrigation and nitrogen fertilizer for the Zea mays crops in arid region

Highlights: • Soil microbial biomass decreased as mulching area decrease for different mulch-type. • Bio-film mulching shorted turnover time of soil microbe by 9.4 day than no mulching. • Soil enzyme activity was similar between bio-film and plastic-film mulching. • An irrigation of 22.5 mm and N-fertilizer of 280 kg ha⁻¹ was the optimal strategy. Biodegradable film mulching (BM) is considered as the best alternative to plastic film mulching (PM) since it can prevent pollution caused due to plastic residues. However, the differences in soil microbial biomass and enzymatic activities between BM and PM, especially for different soil water and nitrogen contents remain ambiguous. In this study, the effects of BM, PM, and no film mulching (NM) on soil microbial biomass C (C_mic), N (N_mic), soil enzymes, and soil C/N ratio in a cornfield were evaluated using experimental data from 2018 and 2019. Additionally, different irrigation depths (30 mm, 22.5 mm, and 15 mm) and N-fertilizer application levels (280 kg ha⁻¹ and 210 kg ha⁻¹) were used in BM. The experimental results demonstrated no apparent differences between the C_mic, N_mic, and soil enzymes between BM and PM in the early stage (elongation stage), but these values under BM were significantly lower than that of PM in the middle stage of crop growth (tasseling and filling stages). Soil sucrase, catalase, and urease under PM were increased by 20.2%, 0.6%, and 12.0%, respectively, compared to BM. The analysis of C_mic, N_mic, soil enzymes, and crop yield under different irrigation and N-fertilizer application levels demonstrated the preponderance of BM_{22.5, 280,} showing the highest yield of 14,110.1 kg ha⁻¹ and NUE of 61.7.