Soil Water-Salt Dynamics and Maize Growth as Affected by Cutting Length of Topsoil Incorporation Straw under Brackish Water Irrigation

Abstract

Brackish water has been utilized extensively in agriculture around the world to cope with the global water deficit, but soil salt accumulation caused by brackish water irrigation cannot be ignored. Straw incorporation has been confirmed an effective sustainable means to inhibit soil salt accumulation. An experiment was conducted in growth tanks over two consecutive growing seasons to investigate the effects of wheat straw incorporation on soil moisture and salinity under brackish water irrigation (5g NaCl L−1). Furthermore, the trial investigated the effects of three wheat straw cutting lengths (CK = 0 cm; L1 = 5 cm, L2 = 10 cm, and L3 = 20 cm) on soil water-salt dynamics and summer maize growth. The results showed that soil properties and maize yields were favorably and significantly affected by the shorter straw segments incorporated into the cultivated field (p < 0.05), as indicated in the decrease in soil bulk density (7.47%–7.79%) and the rise of soil organic matter (SOM) content (2.4–4.5g kg−1) and soil total porosity (4.34%–4.72%) under treatment L1. Meanwhile, treatment L1 produced the greatest dry above-ground biomass (14447 ± 571 kg ha−1), 100-grain weight (34.52 ± 1.20 g) and grain yield (7251 ± 204 kg ha−1) of summer maize. Soil water content in the cultivated layer increased 4.79%–25.44%, and the soil salt accumulation rate decreased significantly due to the straw incorporation and the highest value of soil moisture content (19.10%–21.84%), as well as the lowest value of soil salt accumulation rates (2.12–9.06) obtained at treatment L1. Straw incorporation with cutting length in 5 cm is the optimal choice for alleviating the adverse effects due to brackish water irrigation and improving soil properties, which could be helpful for agricultural mechanization and straw field-returning practices.