Ameliorating C and N balance without loss of productivity by applying mulching measures in rainfed areas

Abstract

Farmland mulching is applied widely as a soil management practice, especially in rainfed areas with scarce water resources. However, it is not clear how continuous mulch application might affect the carbon and nitrogen budget in rainfed agroecosystems. Therefore, we evaluated the impacts of different mulching measures (SM: flat planting pattern with full straw mulching; RM: ridge–furrow construction with half plastic film mulching; PM: flat planting pattern with full plastic film mulching; BM: flat planting pattern with full biodegradable film mulching; and NM: conventional tillage without mulching) on the maize yield, net ecosystem carbon budget (NECB), net global warming potential (NGWP), greenhouse gas intensity (GHGI), and N surplus or deficiency. The results showed that compared with NM, the maize yield decreased significantly by 10.0% under SM, whereas the mulching treatments (RM, PM, and BM) significantly increased the maize yield by 15.1–24.4% (P < 0.05). SM, RM, and PM significantly increased CO2 emissions (24.8–38.2%), N2O emissions (21.1–47.1%), and NGWP (20.8–45.5%), but reduced NECB. By contrast, BM increased NECB and significantly reduced GHGI (P < 0.05). Regardless of the mulching method applied, the N balance indicated an N surplus. Each mulching treatment (SM, RM, PM, and BM) increased the harvested N removal (47.9–179.9 kg N ha–1) and decreased the N leaching loss (8.8–35.9 kg N ha–1). RM, PM, and BM inhibited the ammonia volatilization rate, whereas SM promoted it. PM and BM achieved a lower N surplus. In conclusion, biodegradable film mulching (BM) can significantly reduce GHGI and the risk of N losses while also ensuring high crop yields, and thus it can be used as a high-yield and sustainable production method in rainfed areas.