Improving effect of mulching methods on moderately saline soil and sunflower yield

Soil surface mulching with plastic film or crop straws can prevent secondary soil salinization and improve crop water use efficiency (WUE). An experiment was conducted in a moderately saline field to investigate the effects of different mulching methods on soil characteristics and sunflower yield. Seven treatments were conducted in the study, including 9 000 kg·hm^-2 chopped maize straw mulching (F0.9), 6 000 kg·hm^-2 chopped maize straw mulching (F0.6), whole maize straw mulching (YZ), whole sunflower straw mulching (KZ), plastic film mulching (DM), second-used plastic film mulching (MG) and no mulching (CK). The study analyzed the effects of different mulching methods on soil water and salt movement, sunflower yield and economic benefits of moderately saline soils. The aim of the study was to improve production effects of surface mulching of saline soils. The results showed that salt contents in the 0 5 cm soil layer under treatments of F0.9, YZ and DM decreased while those under MG, F0.6, KZ and CK treatments increased at harvest compared with thoes at sowing. Also salt contents at the 0 20 cm soil layer under F0.9 and DM treatments decreased while those under F0.6, YZ, MG, KZ and CK treatments increased at harvest compared with those at sowing. Different mulching treatments had significantly different effects on soil salt content in the 0 20 cm soil layer. The effects of different mulching methods on soil salt content were inclined to similar with increasing soil depth. In terms of salt content in the 0 20 cm soil layer, F0.9 treatment was the lowest, which suggested that F0.9 treatment had the best salt inhibitory effect. The inhibitory effects on soil salt of mulching measures of DM and F0.6 were similar. For different straw mulching treatments, the inhibitory effects on soil salt of F0.9 and F0.6 were better than those of YZ and KZ. For different plastic film mulching treatments, the inhibitory effect on soil salt of DM was better than that of MG. In the 0 5 cm and 0 20 cm soil layers, average soil water content under DM treatment was higher than those under straw mulching treatments throughout the entire growth period of sunflower. Average soil water content under chopped straw mulching treatments (F0.9 and F0.6) were higher than that under whole straw mulching treatments (YZ and KZ) throughout the growth period. Compared with CK, DM and F0.9 improved 0 100 cm soil water storage significantly. Treatments F0.9 and DM decreased soil water variation coefficients in the 0 100 cm soil layer and thereby maintained stable soil water content throughout the growth season. The order of sunflower yield for different treatments was DM > F0.9 > YZ > F0.6 > MG > KZ > CK. The different mulching methods enhanced crop WUE by improving farmland environment. WUE under DM, F0.9, YZ treatments was higher than those under the other treatments. Output-input ratios of DM, MG, YZ, F0.9 and F0.6 treatments were significantly higher than that of CK. The net income and output-input ratios of DM and MG treatments were significantly higher than those of straw mulching treatments. For moderately saline soils, plastic film mulching was the most effective method. Among the straw mulching treatments, F0.9 treatment was the best mulching method. Compared with the other mulching methods, water retention, salt inhibition, and yield effects of KZ treatment were bad. Thus sunflower straw (KZ) was not a suitable mulching material in the study area. The results of the study were suitable for application in guiding the use of mulching methods in Hetao Irrigation District.