A large body of research has emphasized how plastic mulching can benefit crop yields in dryland areas. However, this practice's pollution of the soil, air and environment has only recently attracted attention. We conducted a five-year field experiment with winter wheat as a test crop to evaluate whether plastic mulching can be replaced with straw mulching in dryland areas of the Loess Plateau in China. The obtained results showed that straw mulching (SM) resulted in similar grain yields that were comparable with plastic mulching. More specifically, ridge-furrow plastic mulching plus furrow seeding (RM+FS), whole field plastic mulching (PM) and SM treatments resulted in average yields of 5950, 6447 and 6246kgha-1, respectively. No soil water storage difference was observed at harvest, but SM retained more water during summer fallow and then stored more water prior to seeding, 26mm and 27mm higher that of PM, and 44mm and 46mm higher that of RM+FS, respectively. None of the three treatments caused soil nitrate-N leaching. Furthermore, because straw is a potential source of slow-releasing N, the SM 0-200cm soil profile contained significantly more nitrate-N than the corresponding RM+FS and PM soil profiles. The SM treatment decreased greenhouse gas emissions intensity (GHGI) by 47% and 40% and increased economic return by 13% and 27% when compared to the PM and RM+FS treatments, respectively. Therefore, an optimized SM system is a viable alternative for increasing crop yields in dryland wheat production that avoids the negative impacts of the increasingly popular plastic mulching approach.
Keywords: Dryland; Ridge plastic mulching plus furrow seeding; Straw mulching; Whole field plastic mulching plus bunch-seeding; Winter wheat.
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