[Effects of cultivation patterns on wheat yield and soil fertility in dryland]

A field experiment was conducted to examine the effects of plastic film mulching (PM), straw retention (SR), and planting green manure (GM) on winter wheat grain yield and soil fertility. The results showed that PM did not have consistently positive effect on the grain yield, when compared to the traditional patterns (TP). No difference of average grain yield was observed between them over three years. Soil total nitrogen (N), available phosphorus (P), potassium (K), sulfur (S), zinc (Zn) and manganese (Mn) were decreased in 20-40 cm layer in PM than those in TP, while no difference was observed for soil organic matter, nitrate (NO₃^--N), available iron (Fe) and copper (Cu). The mean grain yield of three years decreased by 12.1% in SR than that in TP treatment. At maturity stage of winter wheat, soil total N and available Cu was increased by 5.8% in 0-20 cm and 6.2% in 20-40 cm layer, respectively, while soil available P and Mn were decreased by 36.1% and 10.2%, respectively. No difference was observed between SR and TP treatments for soil organic matter, NO₃^--N, available K, S, Zn and Fe at anthesis and maturity stages. Compared to the TP treatment, the mean grain yield was decreased by 12.1% in GM treatment. Soil pH, available P and S were decreased, while the soil organic matter, total N, NO₃^--N, and available Zn and Mn were increased. No difference was observed for soil available K, Fe and Cu. In conclusion, the PM and SR were not beneficial for the improvement of soil fertility, and thus inhibited the grain yield increase in dryland with low soil fertility level. The GM has greater potential to increase soil nutrients, but it should be paid more attention to the risk of grain yield reduction due to insufficient annual precipitation.