Effects of straw strip mulching on soil water-temperature in root zone and grain yield of sorghum in southwest dryland, China.

To address the low-yield of sorghum caused by high temperature and drought stress during the growing season in the drylands of Southwest China, we conducted a field experiment in a typical rain-fed dry farming area of Guizhou Province from 2021 to 2022. The treatments included ridge planting with plastic film mulching strips only on the ridges (RFM), single-row planting with a double-35 cm structure under whole maize straw strip mulching (SMN), and double-row planting with a double-70 cm structure under whole maize straw strip mulching (SMW), with conventional flat open-field planting as the control (CK). We investigated the effects of strip mulching on the dynamics of soil moisture and temperature in the root zone and grain yield of sorghum. The results showed that the three strip mulching treatments significantly increased soil water content in the 10 cm and 20 cm depths by 29.8% and 27.1% over the two years, respectively. SMN and SMW exhibited moisture preservation effects comparable to RFM. SMN and SMW generally reduced soil temperature across growth stages, with an average decrease of 1.3 ℃ in the 5-20 cm soil layer during the entire growth period. The effective accumulated soil temperature decreased by an average of 78.3 ℃, while the whole growth period was prolonged by an average of 7 days. In contrast, RFM showed significant warming effects mainly before jointing and at maturity stages. The average soil temperature in the 5-20 cm layer was increased by 0.9 ℃ under RFM, and the growth period was shortened by 6 days. SMN and SMW significantly reduced the diurnal soil temperature amplitude by 0.7-3.4 ℃, forming a more stable thermal environment compared to CK and RFM. SMN, SMW, and RFM all significantly increased the grains number per spike and the aboveground biomass per sorghum plant, with grain yields being increased by 16.0%-31.0%, 13.0%-25.6%, and 22.5%-50.4%. In conclusion, while maintaining the yield-increasing advantage, whole maize straw strip mulching resolved the problems of extreme high temperature and drought stress caused by plastic film mulching in midsummer. Furthermore, it featured a higher straw utilization rate and lower production costs. SMN performed the best and would be suitable for application as a green production and cultivation technology for sorghum in the drylands of Southwest China.