Effects of Water Saving Practices on Winter Wheat and Summer Maize Yields in South Loess Plateau of Northwest China

A field experiment, laid out in Randomized Complete Block Design (RCBD) with split plot arrangement having four replications, was conducted at the south edge of Loess Plateau, Shaanxi, China to evaluate the responses of winter wheat and summer maize to different water saving management practices involving four mulching and irrigation treatments, i.e., plastic mulch ridge and straw mulch furrow combined with deficit irrigation (RF+DI), straw mulch combined with deficit irrigation (SM+DI), Deficit Irrigation (DI), and Conventional Flood Irrigation (CFI). Soil temperature and moisture during the crop growth were monitored in two years. RF+DI treatment significantly increased maize yield, and it also had higher wheat yield than SM+DI treatment. SM+DI treatment increased maize yield; however, it did not increase winter wheat yield. Soil water content in RF+DI and SM+DI treatments was significantly higher than those of CFI or DI treatments. Compared with RF+DI treatment, SM+DI treatment had higher soil water content (0-20 cm); however, it had the lowest heat 741 Degree Days of Soil (DDs) among the four treatments. The low soil temperature in SM+DI plots, especially in early spring, delayed winter wheat growth stages and development, thus reduced grain yield compared with RF+DI treatment. The positive effects of ridge-furrow system on both wheat and maize yield could be explained by harmonizing soil moisture and temperature by this treatment.