Multi-site assessment of the effects of plastic-film mulch on dryland maize productivity in semiarid areas in China

Transparent plastic-film mulch combined with ridge-furrow technology is widely used to improve crop productivity in cold semiarid areas of China, but whether the technology has similar benefits in different climatic environments is not known. The present study was initiated to assess the variation of plastic-film mulch on maize (Zea mays L.) production in different semiarid environments. Four treatments: (i) plastic-film mulch, (ii) straw incorporation in soil without plastic-film mulch, (iii) straw incorporation plus plastic-film mulch, and (iv) no plastic-film mulch or straw incorporation (control) were imposed in ridge-furrow prepared fields at five sites along a hydrothermal gradient for up to 6 years. Compared to non-mulched plots, maize grain yield and aboveground biomass in mulched plots increased by 30-107% and 37-69%, respectively, across sites due to increased soil temperature and moisture principally during early growth. Plastic mulch increased grain yield to a greater extent at sites with higher hydrothermal limitations. Plastic mulch increased the harvest index of maize at cooler sites, but showed a decrease in harvest index at warmer sites, compared with no mulch. The mulch decreased the year-to-year variation in maize yield at the more hydrothermally-limited sites, but increased the variation at less hydrothermally-limited sites. Compared to no straw incorporation, straw incorporation increased grain yield and aboveground biomass by 7-12% and 8-12%, respectively, across the five sites. The present study suggests that the benefits of plastic-film mulch on maize grain yield and its stability varied significantly with local climatic conditions and that plastic-film mulch can be preferentially applied for maize production where both insufficient rainfall and low spring temperatures are limiting factors.