Different mulching materials influence the reclamation of saline soil and growth of the Lycium barbarum L. under drip-irrigation in saline wasteland in northwest China

The plastic mulch has been widely used for salinity controlling in arid-saline area for decades, but the residual plastic shows serious hazards to human and environmental health nowadays. To find an alternative from potential materials, a mulching experiment consisting of 4 treatments, the sown grass cover (GC), the black plastic film (BF), the straw curtain (SC), and the bare soil (CK), for the Lycium barbarum L. (LL) cultivation was conducted for 2 years. The soil physical and chemical parameters and LL responses were comprehensively evaluated. Results showed the average soil water content during a single irrigation interval was the highest in BF, followed by SC and CK that were comparable, and the lowest in GC in both years. The average soil temperatures within 0-20 cm depth in midsummer in BF was 4.1, 4.5 and 1.9 celcius higher than those in SC, GC and CK, respectively. The soil desalination rates in GC, BF, SC and CK were 47.9%, 46.5%, 66.2% and 45.0% when compared with the initial salinity in the first year. And those became 43.6%, 82.5%, 73.5% and 76.4% when the second year terminated. The growing parameters of the LL in SC and CK were significantly larger than other treatments. The high soil temperature in BF and the water competition of sown grass in GC had adverse effects on the survival rate, growth, and photosynthetic efficiency of the LL, resulting in the yields and irrigation water productivities (IWP) in BF and GC being 45.8% and 46.3% lower than CK, respectively. While the yield and IWP in SC were 26.9% higher than CK. Considering the changes of soil parameter and LL response comprehensively, the straw curtain could be the best alternative of plastic film for the LL cultivation in saline soil in low-lying arid area.