Closing the Yield Gap and Achieving High Water Use Efficiency with Field Management Practices in Dryland Wheat: A Case Study on the Loess Plateau

To determine how field management impacts water use of winter wheat, yield gaps and water use efficiency in dryland farming, yield gap analysis based on boundary line analysis was applied. The results showed that plastic film mulching during the fallow period increased evapotranspiration (ET) and wheat yield but had little influence on water use efficiency (WUE) and the yield gap. Compared with no tillage (NT), deep ploughing (DP) increased wheat yield without influencing ET and thus increased WUE. Subsoiling had little influence on the average yield, but it increased the possibility of obtaining a high yield. Compared with drill sowing (DS), drill sowing on plastic film (DSM) increased wheat yield with an increase in ET. DSM also reduced the yield gap to some extent. Appropriate fertilizer application rates are also important for reducing yield gaps. When the yield gap was the lowest, the respective nitrogen and phosphate application rates were 150 ha(-1) and 180 ha(-1), respectively. In conclusion, yield gap analysis based on boundary line analysis makes it possible to evaluate how effectively water is used. This case study on the Loess Plateau showed that plastic film mulch and drill sowing on the edges of plastic film (P-DS) increased wheat yield but had little impact on the yield gap and WUE. Deep ploughing increased wheat yield and WUE and reduced the yield gap. Subsoiling (SS) had little impact on yield and WUE, but it increased the possibility of obtaining a higher yield and reduced the yield gap. Moreover, SS is a more effective technique in wet years than in dry years. (C) 2020 Friends Science Publishers