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
Authors: Adil Muhammad 
Published: December 2022

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.