Effects of wheat straw mulching and wet treatment on soil improvement, greenhouse gas emission, nitrogen leaching, and vegetable yield

Abstract

Plastic tunnels are a crucial tool used for intensive vegetable production in developing countries, however these tunnels have resulted in significant soil degradation. Another issue that the agriculture industry is facing is that an excess of crop straw is produced every year. This paper aims to combat both of these issues by combining them: to relieve soil degradation and consume crop straw, six treatments of three wheat straw quantities (0, 5,000 and 10 000 kg · hm−2) and two soil moisture levels (wet and submergence) were evaluated during two-month high-temperature summers to explore the possibility of applying straw mulching to improve degraded soil in plastic tunnels. Greenhouse gas emission and nitrogen leaching, which are two other significant problems with using intensive vegetable tunnels, were also investigated. Compared to the no straw mulching and wet treatment, the net global warming potential, available nitrogen, nitrogen leaching, and N2O emissions from subsequent crop fields decreased by 389.59%, 21.2%, 45.9%, and 41.5%, respectively. The soil-available phosphorus, available potassium, total nitrogen, total phosphorus, total potassium, organic carbon, microbial biomass carbon, microbial biomass nitrogen, activities of urease, sucrase, and acid phosphatase, and yields of cucumber and tomato increased by 2%, 79.6%, 75.3%, 51.4%, 92.5%, 32.8%, 122.1%, 152.5%, 103.9%, 102%, 88.6%, 19% and 13%, respectively, in the 10 000 kg straw and wet treatment. According to the 15N-site preference value, nitrification was the dominant pathway for N2O production in the field, and its contribution was enhanced by straw mulching and weakened by submergence. Considering all factors, no significant advantage was found for submergence compared with wet treatment, while treatment with 10 000 kg of straw showed remarkable improvement over the treatment with 5,000 kg of straw. We conclude that applying 10 000 kg of wheat straw in conjunction with the wet treatment during the summer fallow period has wide application potential to improve degraded soil, alleviate secondary salinization and nitrogen leaching, and consume crop straw without increasing net global warming potential.