Alternating small and large ridges with full film mulching increase linseed (Linum usitatissimum L.) productivity and economic benefit in a rainfed semiarid environment

The farming practice of alternating ridges-furrows with plastic film mulching is widely used to improve field productivity of most staple crops such as maize and wheat in the semiarid Loess Plateau, but whether the technology has similar benefits on oil crops such as linseed flax (Linum usitatissimum L.), still remains unknown. From 2012-2013, a 2-year field experiment was carried out to evaluate the effects of different ridges-furrows mulching patterns on soil hydrothermal parameters, linseed yield performance, water use efficiency and economic benefit at a rainfed semiarid site of the Loess Plateau. Four different treatments were designed as: i) alternating small and large ridges with full film mulching (RFM), ii) alternating ridges and furrows with plastic film mulching only on the ridges (RM), iii) flat planting with fully film mulching (FM) and iv) conventional flat planting without mulching (CK). Local widely cultivated variety Tianya 9 was used as testing cultivar. The results indicated that soil water storage during early growing stage was increased by 7.1%, 0.6% and 6.3% in RFM, RM and FM, respectively, compared with that of CK across two growing seasons. After harvesting, soil water storage in RFM was recovered to higher level than that of CK. Average soil temperature at seedling stage was 3.1 °C and 2.1 °C higher in RFM and FM than that of CK. In addition, film mulching generally accelerated crop development during early vegetative period, leading to a shorter growing season in RFM and RM. Particularly, both linseed yield and water use efficiency were enhanced by 116.2% and 154.8% in RFM, 50.3% and 72.4% in RM, 87.5% and 84.2% in FM across two growing seasons, respectively, compared with those of CK. Critically, the greatest net income and output to input ratio were achieved in RFM across both growing seasons. Present results clearly suggest that the practice of alternating small and large ridges with full film mulching provide an innovative option to optimize soil hydrothermal conditions, thereby boosting the productivity and profitability of dryland linseed flax in rainfed semiarid environment.