Effects of different tillage systems on soil water conservation, grain yield and water use in winter wheat and spring maize cropping systems: A Meta-analysis

Abstract

Climate change is a major threat to food security. The global population is increasing at a stimulated rate. Wheat and maize are the globally important crops. There is a need to focus on the methods that help to improve crop production. Since, conventional tillage (CT) is the major tillage practice in rain-fed areas. Conservation tillage methods are practiced to conserve soil moisture in order to increase crop productivity. However, the effects of conservation tillage methods under varying soil textures, precipitation and temperature patterns are still unknown. We took data from 119 peer-reviewed published articles and carried a meta-analysis to assess the effects of 3 conservation tillage practices including no tillage (NT), reduced tillage (RT) and subsoil tillage (ST) on precipitation storage efficiency (PSE), soil water storage at crop planting (SWSp), grain yield, evapotranspiration (ET) and water use efficiency (WUE) under varying precipitation and temperature patterns and soil textures in dry land wheat and maize cropping systems. We took conventional tillage as a control treatment and compared it with different types of fallow conservation tillage systems. Compared to conventional tillage (CT), conservation tillage methods overall increased PSE, SWSp, grain yield, ET and WUE by 22.6%, 17.8%, 24.1%, 6.5% and 12.1%, respectively in winter wheat. Among conservation tillage methods, NT had a better performance on SWSp, grain yield and WUE compared to RT and ST. Fine-textured soils showed better response of tillage methods on PSE, SWSp and ET than medium and coarse-textured soils, while medium-textured soils showed greater positive response ratio (RR) of conservation tillage methods on grain yield and WUE. The enhancement of conservation tillage on PSE and grain yield was greater in the regions having mean annual precipitation (MAP) of >600 mm, while crop yield, ET and WUE were greater when MAP was <400 mm. Conservation tillage methods also increased PSE, grain yield and WUE in the regions where mean annual temperature (MAT) was 8-15 ℃, while SWSp was greater when MAT was <8 ℃. In dryland spring maize, conservation tillage overall increased PSE, SWSp, grain yield, ET and WUE by 38.1%, 20.6%, 29.6%, 16.9% and 11.0%, respectively. The regions having medium-textured soils showed better response of tillage methods on PSE, SWSp, ET and WUE, while coarse-textured soils showed greater positive response ratio (RR) of tillage methods on grain yield. Compared to CT, the RR of conservation tillage on PSE, grain yield, ET and WUE was greater when MAP was <400 mm, while SWSp was greater when MAP was 400-600 mm. Conservation tillage also increased PSE, SWSp and ET in the regions where MAT was <8 ℃, while grain yield and WUE were greater when MAT was >15 ℃. We conclude that NT is a global promising practice among all conservation tillage methods to increase soil water storage and crop production under varying precipitation and temperature patterns and soil textures in both winter wheat and spring maize cropping systems.