Response of productivity and nitrogen efficiency to plastic-film mulching patterns for maize in sub-humid northeast China

In the semi-humid region of northeast China, the plastic-film mulching (PFM) is essential for sustaining yields, while the yield-increase potential and nitrogen (N) use mechanism under different PFM patterns in this area remain poorly understood. A field experiment using maize (Zea mays L.) was conducted for two consecutive years to study the effects of different PFM patterns on soil microclimate factors, N mineralization, N loss, crop yields and N use efficiency under drip irrigation. The six treatments consisted of full ridge-furrow mulching (FM), only ridge mulching (RM), non-mulching (NM), ridge-furrow mulching without fertilization (CFM), ridge mulching without fertilization (CRM), and non-mulching without fertilization (CNM). The results showed that the PFM could obviously warm the soil throughout the growing season. Compared to NM, FM and RM obviously increased the soil temperature by 2.0–5.4 ℃ and 1.6–4.8 ℃ in the 2017 season, respectively, and by 1.9–7.8 ℃ and 1.0–5.7 ℃ in the 2018 season, respectively. Across two years, soil temperature was highest for FM followed by RM and NM. In general, FM enhanced the soil water content compared with RM, especially in the 0–50 cm profile throughout the growing season. The PFM could significantly (p < 0.05) promote soil N mineralization (Nmin). Furthermore, irrespective of fertilization, the PFM significantly (p < 0.05) improved plant N uptake (Nuptake), grain N accumulation (Ngrain) and N harvest index (NHI). Averaged across years, full ridge-furrow mulching and only ridge mulching distinctly enhanced the NHI under fertilization by 6.8% and 6.1%, respectively, relative to non-mulching. Finally, PFM imposed significant influence (p < 0.05) on ear barren tip, 100-seed weight and grain yield. Grain yield under FM and RM were significantly promoted by 15.0% and 12.5%, respectively, compared with NM. Meanwhile, full ridge-furrow mulching could obviously increase grain yield compared to ridge mulching. In conclusion, full ridge-furrow mulching provided a more feasible water-heat environment for soil N mineralization, improving plant N uptake and reducing N loss, and thereby significantly increasing crop productivity and nitrogen use efficiency.