No-tillage with mulching improves maize yield in dryland farming through regulating soil temperature, water and nitrate-N

Abstract

Nitrogen (N) losses from cropland soils contribute to a series of ecological problems. No-tillage and mulching are widely regarded as practices that can minimize the disturbance of the agro-ecosystem and regulate the water cycle in dryland farming. However, detailed understanding of water and nitrate-N transport in soil and their effects on the soil ecosystem under no-tillage with mulching is lacking. To improve our understanding, a long-term continuous maize field experiment was conducted in the southern Loess Plateau, China. This article reports experimental data form a complete growth year for spring-sowing maize, including the fallow period (from October 2017 to April 2018) and the growth period (from May 2018 to September 2018) after 15 years maize planting. Treatments included conventional tillage (CT), no-tillage (NT), no-tillage with biochar (NB), no-tillage with straw mulching (NS), no-tillage with plastic film mulching (NP), and no-tillage with straw-plastic film mulching (NSP). Overall, the results revealed that the effect of different treatments on soil temperature gradually weakened with increased maize growth and increased soil depth. The NP had the highest average temperature during the whole growth period, and NS had the lowest. Average soil profile water content (SWC) and the soil water storage (SWS) of the mulching treatments (NSP, NP, NS) were higher than the non-mulching (CT, NT, NB) at each stage. The SWS of NSP in the maturity period was significantly greater by 7.1 % compared with CT. Our results indicated that there was no nitrate-N leaching in NSP and NP below 40 cm, and the nitrate-N accumulation followed the order of CT > NT > NS > NB > NP > NSP. Conventional tillage exhibited a nitrate-N accumulation peak in deep soil layers (140−180 cm), while nitrate-N peaks of the NT, NS, and NB treatments in the shallow soil layers (40−90 cm) decreased with seasonal variation. However, the NSP and NP increased yields by 36.5 % and 34.1 %, NT decreased yields by 14.8 %, respectively, compared to CT. These suggest that no-tillage alone (NT) does not effectively improve soil water use efficiency and may even reduce yields, but reduce nitrate leaching. No-tillage with straw-plastic film mulching (NSP) was the most effective measure to facilitate the sustainable development of agriculture in dryland farming.