Exploring optimal soil mulching for the wheat-maize cropping system in sub-humid drought-prone regions in China

Abstract The application of soil mulching is widely used to improve crop productivity within semi-arid regions of China, but little is known when using a crop rotation system in the sub-humid drought-prone regions as to whether the mulching practice may perform as well as in semi-arid regions. A field study was conducted during two consecutive cycles of a wheat (Triticum aestivum L.) - maize (Zea mays L.) cropping system within the Yangling District of Northwest China to evaluate the effects of different mulch cultivation practices on soil water contents and soil temperatures (EM50 probes), crop yields, and water use efficiency (WUE). Four treatments were evaluated: (1) a flat plot without mulch control treatment (CK), (2) a flat plot with straw mulch (SM), (3) a flat plot with plastic film mulch (PM), and (4) a ridge-furrow planting with film mulch over the ridge and wheat straw mulch over the furrow (PSM). All mulch treatments significantly improved grain yields and WUE of the winter wheat and summer maize in comparison with CK. The highest grain yields and WUE occurred in the PSM treatment over the two wheat-maize cycles. The average soil water storage within the 0–200 cm soil layer was 3.82%, 2.25%, and 1.31% higher under the PSM, PM, and SM treatments, respectively, in comparison to the CK treatment.Although the soil mulching practices insignificantly changed the total crop evapotranspiration (ET) with a small quantity compared with non-mulched treatment, they tended to reduce non-productive soil evaporation (E) and increase productive plant transpiration (T). All mulching treatments increased the soil temperature of the winter wheat from the seedling to the regreening stages and helped prevent freeze damage. The PSM and SM treatments effectively inhibited the excessive soil temperature rise during the growth stage for summer maize. The PSM treatment resulted in favorable soil moisture and temperature conditions that increased the grain yields and water use efficiency of winter wheat and summer maize. Therefore, we concluded that ridge-furrow planting with film mulch over ridge and wheat straw mulch over the furrow is an effective management practice to increase yields and WUE in a winter wheat-summer maize crop rotation within this sub-humid drought-prone region.