Straw and plastic management regulate air-soil temperature amplitude and wetting-drying alternation in soil to promote intercrop productivity in arid regions

Abstract

Soil coverage with straw and plastic mulch is a valuable and useful strategy for enhancing crop production in arid regions. However, a better understanding of the mechanism by which this innovative practice drives spatial and temporal variation in soil temperature and water content and improves crop production could guide cropping system optimization. A three-year field experiment was performed with four wheat-maize strip-intercropping treatments: 1) no-tillage with 25−30 cm tall wheat straw standing in wheat strips and residual plastic mulching in maize strips (NTS), 2) no-tillage with 25−30 cm tall wheat straw mulching in wheat strips and residual plastic mulching in maize strips (NTM), 3) conventional tillage with 25−30 cm tall wheat straw incorporation in wheat strips and annual new plastic mulching in maize strips (CTS), and 4) conventional tillage without wheat straw retention in wheat strips and annual new plastic mulching in maize strips (CT). The temporal and spatial variation in soil temperature and soil water content was assessed. NTM had the greatest soil water retention, and increased soil water content in the 0−120 cm soil depth by 6.4, 5.2, and 5.4 % at the wheat independent growing period, intercrops co-growing period, and maize independent growing period, respectively, compared with CT. In the 0−15 cm soil depth, compared with CT, NTS decreased soil temperature by 0.73, 1.18, and 0.85 °C, NTM decreased it by 1.35, 1.95, and 1.38 °C, during the three aforementioned crop growing periods. With the intercropping treatment, soil temperature in the 0−15 cm soil depth of maize strips was higher than that of wheat strips with NTS by 1.13, 3.67, and 1.44 °C, and with NTM higher by 1.32, 2.97, and 1.75 °C, especially higher as 1.38, 4.00,and 1.68 °C with CT, during the three aforementioned crop growing periods. According to the value of difference between air and soil temperatures, NTM maintained soil heat in the low temperature season and reduced soil temperature in the high temperature season. These allowed the intercrops to grow in a collaborative state with the NTM treatment during their growing period, it is an important regulation mechanism for growth and development of intercropped wheat and maize. NTM improved total grain yield of wheat plus maize by 14.9 % in comparison to CT. The optimized soil temperature and increased soil moisture for the intercrops’ strips with NTM indicates that the integrated set of practices in this treatment can be used as a superior technique to overcome simultaneous water shortage and heat stress in arid irrigated areas of northwestern China.