Effect of Forage Brassica on Subsequent Soil Water Content and Yield of Dual-Purpose Winter Wheat in Rainfed Region of Northwestern China

The dual-purpose performance of winter wheat used for both forage and grain production has been explored as an alternative practice for filling the feed gap during winter and spring in agricultural areas of the Loess Plateau. Profit-ability is still restricted however, because of a three month summer fallow period between harvest and planting of the subsequent wheat crop. During this 3 month period 60% of the annual precipitation occurs, limiting the effective use of soil water and compounding the risk of soil erosion. Thus it is important to cultivate some forage crops with higher water consumption, protecting the ecological environment during this period and enlarging the forage resource base through their high forage yield and good quality. A previous study has shown that inclusion of rapeseed into crop rotations could reduce disease in subsequent plantings, leading to an increase in production of the following wheat crop (Brendan and John 2004). Accordingly, dual-purpose winter wheat after forage brassica may be an effective option to meet these requirements. Other studies have shown however, that wheat yield of grazed plots following brassica was reduced by 29% compared with that of grazed plots following fallow, and that average grain yield in grazed plots was reduced by 38% compared with that in ungrazed plots (Kelman and Dove 2007). Additionally, the possibility of severe water stress occurring after forage crop harvest is an important concern. In this study, soil moisture status and forage and grain yield of dual-purpose winter wheat following forage brassica were investigated and compared with those of winter wheat after fallow