Ridge-furrow full film mulching: An adaptive management strategy to reduce irrigation of dryland winter rapeseed (Brassica napus L.) in northwest China

Abstract

Ridge-furrow full film mulching (RFFM) has been widely adopted as a water-saving and yield-improving planting pattern in arid and semi-arid regions. Whether or not RFFM can replace the conventional flat planting pattern (FP) with supplemental irrigation in dryland farming has not been tested. Moreover, the effects of reducing irrigation frequency and amount on crops in dryland farms under different rainfall years (dry, normal or wet years) remain unknown. Present study selected winter rapeseed (Brassica napus L.) as a test crop for a three-year field experiment to investigate the irrigation water-saving potential of RFFM. Six treatments: 1) FP without irrigation (FP0); 2) FP with 30-mm irrigation at the overwintering stage (FP1); 3) FP with 30- and 60-mm irrigation at the overwintering and stem-elongation stages, respectively (FP2); 4) FP with 30-, 60- and 60-mm irrigation at the overwintering, stem-elongation and flowering stages, respectively (FP3); 5) RFFM without irrigation (RFFM0); and 6) RFFM with 45-mm irrigation at the flowering stage (RFFM1) were conducted to explore their effects on root and shoot biomass, nutrient uptake, yield, oil production, evapotranspiration (ET) and water use efficiency (WUE). The results indicated that RFFM0 significantly promoted root and shoot biomass accumulation and nutrient uptake. Thus it significantly improved yield by 23.7–39.0%, oil production by 26.8–43.3% and WUE by 71.3–86.5%, and simultaneously decreased ET by 21.2–29.7% in comparison to FP0 and FP1 in dry, normal and wet years. Furthermore, the yield-increasing effect in RFFM0 was nearly equal to FP3 in the normal rainfall and wet years, and was equivalent to FP2 in the dry year. Yield and oil production in RFFM1 were significantly higher than in RFFM0, and were commensurate with those in FP3 in the dry year. Therefore, RFFM reduced a two-time application with total 90 mm irrigation water in a dry year, as well as a three-time application with total 150 mm irrigation water in normal rainfall and wet years for dryland winter rapeseed. Overall, RFFM is a promising adaptive agronomic strategy to apply in dryland regions to sustain food security, and cope with water scarcity, a potential threat to dryland farming due to climate change.