4.4. Correlations of wheat and maize grain yield, ET and
WUE to SWSp
The RR of wheat and maize grain yield increased linearly with increase
of the RR of SWSp for conservation tillage practices (Figure 6). An
increase of 24.1% in wheat and 29.6% in maize yields can be explained
by the increase of the RR of SWSp for conservation tillage practices.
The RR of ET to SWSp under conservation tillage methods was significant
for wheat but remained non-significant for maize. Similarly, the RR of
wheat and maize WUE was also related to with that of SWSp, which can be
attributed to 12.1% increase in wheat and 11.0% increase in maize WUE
under conservation tillage methods (Figure 6).
Conclusion
The meta-analysis results showed that conservation tillage methods
overall increased soil water storage, grain yield and crop water use in
both winter wheat and spring maize cropping systems compared to
conventional tillage. Although overall conservation tillage methods
increased PSE, SWSp, grain yield, ET and WUE in both of the cropping
systems but the intensity was greater in spring maize as compared to
winter wheat. Soil texture and precipitation pattern played a
significant role in determining the results. High precipitation
increased PSE, SWSp and wheat grain yield and the effect was opposite in
case of maize. Fine-textured soil increased PSE, SWSp and ET in both of
the cropping systems while medium-textured soil showed increased grain
yield and water use in both cropping systems. Even though different
conservation tillage methods had variable effects on soil water
conservation under different edaphic and climatic conditions, however,
overall conservation tillage methods can improve soil physical health
and enhance crop productivity to obtain food security under climate
change scenario.