Impacts of ridge with plastic mulch-furrow irrigation on soil salinity, spring maize yield and water use efficiency in an arid saline area

The inadequate soil and water management has resulted in ecological and environmental problems in Hetao Irrigation District, which is characterized by low precipitation, high evaporation and soil salinity issues. A two-year field experiment was conducted to investigate the effects of the combined application of irrigation methods, irrigation amounts and plastic mulching modes on soil moisture, soil salinity, and water use efficiency of spring maize. This experiment included four treatments: (i) border irrigation partially mulched by plastic film with full irrigation amount (CK), (ii) ridge-furrow irrigation not mulched by plastic film with high irrigation amount (NRF), (iii) ridge with plastic mulch-furrow irrigation with high irrigation amount (PRF), (iv) ridge with plastic mulch-furrow irrigation with low irrigation amount (PRL). The results demonstrated that soil water and soil salinity mainly changed in the upper 80 cm soil layer. The proportion of the amount of deep percolation in the total growing season ranged from 9.3% to 29.5% and the highest deep percolation amount appeared in CK. Less irrigation amount generally resulted in a higher salt accumulation in the upper 40 cm soil layer. At harvest, the highest salt accumulation appeared in PRL and the lowest salt accumulation appeared in PRF among the three ridge-furrow irrigation treatments. Compared with the CK treatment, the average grain yields in the PRF, PRL and NRF treatments were increased by 29.6%, 12.2% and 14.4% in 2015, and increased by 5.5%, 4.2% and 2.5% in 2016, respectively. The highest water use efficiency was found in the treatment with PRF in 2015 growing season, and in the treatment with PRL in 2016 growing season. Irrigation water use efficiency was lower in PRF than in PRL, whereas higher than in CK and NRF. Fully considering maize yield, soil water storage, soil salt balance and water use efficiency in the Hetao Irrigation District, ridge with plastic mulch-furrow irrigation with about 300 mm of irrigation water can be recommended as the effective soil and water management practice.