The combined effects of maize straw mulch and no-tillage on grain yield and water and nitrogen use efficiency of dry-land winter wheat (Triticum aestivum L.)

Abstract

Excessive soil evaporation induced water loss resulting in drought stress is a significant yield-limiting factor in dry-land regions of China. However, the crop yield response to straw mulch and tillage depends on the cumulative rainfall that varies greatly from year to year due to frequent occurrences of extreme weather events. The aim of this study was to investigate the responses of grain yield and water and nitrogen use efficiency to mulch-based no-tillage in both humid and dry climates. The experiment was laid out in split plot design using tillage as a main factor and maize straw mulch as sub-plot with three replications each. Maize straw mulch combined with no-tillage was able to conserve soil moisture (0.348 cm3 cm–3 vs. 0.398 cm3 cm–3) at tillering stage and reduce daily variation of soil temperature in the topsoil layer, and thereby increased the maximum number of wheat tillers and fertile spikes by 51.3% and 72.3%, respectively, compared to the no-mulch control. The favorable soil hydrothermal regime also enhanced the activities of soil urease and neutral phosphatase, which activated the release of plant-available soil N and Olsen–P by 61.4% and 43.2%, respectively, compared to the no-mulch control. Improved plant-available soil N lead to greater root system vigor and root surface area and thus promoted the nitrogen uptake efficiency (NUpE), maximum value of LAI and the plant assimilate accumulation. The grain yield, WUE and nitrogen utilization efficiency (NUtE) in mulch-based no-tillage were 36.8%, 16.0% and 14.8% greater, respectively, than those in no-mulch control, and they were more effective in a dry climate than in a humid climate. These results suggest that maize straw mulch combined with no-tillage can not only conserve soil moisture for wheat tillering but also activate the release of plant-available soil N and plant N acquisition for higher grain yield and water and nitrogen use efficiency.