Effects of mulching materials and furrow-to-ridge ratios on oat grain/hay yield and water use efficiency under rainwater harvesting cultivation

In order to improve soil water content and rainwater utilization in the semiarid Northwest China region, a field experiment of a randomized complete block design was conducted in 2012 at Dingxi Arid Meteorology and Ecological Environment Experimental Station of the Institute of Arid Meteorology of China Meteorological Administration. The experiment investigated the effects of different mulching materials biodegradable mulch film, common plastic film, no mulching (compacted soil with soil crust) and furrow-to-ridge ratios (60 cm∶30 cm, 60 cm∶45 cm and 60 cm∶60 cm) of rainfall harvesting cultivation with ridge and furrow on soil water storage, hay yield, grain yield, yield components and water use efficiency (WUE) of oat, with the conventional planting as the control. Also the economic benefits of rainfall harvesting cultivation with ridges and furrows were investigated. The results showed that the order of soil water storage was ridge covered with common plastic film (CMR) ≈ ridge covered with biodegradable mulch film (BMR) > ridge with compacted soil (SR) > traditional planting (TP). Also soil water storage increased with increasing ridge width. Hay yield, grain yield and WUE of oat under SR planting were respectively 12%, 18% and 27% lower than those under TP planting. While these variables were respectively 5%, 4% and 14% higher under BMR planting, they were 7%, 9% and 23% higher under CMR planting, compared with TP. In most cases, hay yield, grain yield and WUE of oat decreased with increasing ridge width. Based on regression analysis, oat grain yield under CMR planting reached the maximum of 2 213 kg·hm^-2 under furrow-to-ridge width ratio of 60 cm∶38 cm. The maximum oat grain yield of 2 114 kg·hm^-2 under BMR planting was for furrow-to-ridge width ratio of 60 cm∶34 cm. On average, the economic benefits of oat were respectively 5 194 Yuan·hm^-2, 4 557 Yuan·hm^-2, 4 889 Yuan·hm^-2 and 5 637 Yuan·hm^-2 under TP, SR, BMR and CMR planting systems. Taking grain yield, WUE and environmental protection into account, biodegradable mulch film with ridge-to-furrow width ratio of 60 cm∶34 cm was best for oat planting in the semiarid Loess Plateau regions.