Abstract:Plastic mulching (PM) technology can effectively improve the crop productivity in the dryland. However, few studies have been conducted to determine PM effect in different soil moisture conditions before sowing. Based on the winter wheat-summer maize rotation experiment with PM from 2013—2016, the Aquacrop model was tested, and then different levels of soil moisture before sowing were set up in Baoji, Wugong, and Xi’an using the historical climatic data. The response law of the plant growth and water use during summer maize growing seasons to soil moisture before sowing was explored under PM, and the criterion for using PM was established. Results showed that when the initial soil water content before sowing (ISWC) was less than 70% of field capacity (FC), the maize yield greatly fluctuated in the three sites. The yield increment for both non-mulching and PM treatments increased with the precipitation. With the increasing ISWC, the increment in yield became more and more obvious, which was less and less sensitive to precipitation, and finally tended to be stable under PM. When ISWC reached 80%~85% of FC, the maize water use efficiency under PM reached the highest level. To sum up, the soil water availability was one of the prerequisites for the yield promotion effect under PM. When the ISWC is less than 70% of FC, PM is not recommended; when the ISWC is greater than 80% of FC, PM is recommended to farmers.