Quantitative analysis in regulation effects of water-fertilizer in semi-arid farmland

Based on a field study in the semi-arid Loess plateau of China, the strategies of limited irrigation on farmland in dry-period and pre-sowing of normal-precipitation years are studied comparatively, and the difference effects on water use and grain yield of spring wheat with dry-period irrigation, pre-sowing irrigation and fertilizer application are examined. The results indicate that both dry-period irrigation and pre-sowing irrigation conduce to larger and deeper root systems, compared with the non-irrigated treatments. However, the promoting effect of dry-period irrigation is more significant under the same amount of supplemental irrigation and dry-period irrigation is more beneficial for the increase of grain yield. Furthermore, dry-period irrigation is more beneficial for improving WUE and grain yield of spring wheat than pre-sowing irrigation, and fertilizer application is more favorable for improving yield than without fertilizer application. The combination of dry-period irrigation and fertilizer application is the most efficient way for improving WUE and grain yield of spring wheat.