Application of carboxymethyl cellulose sodium (CMCNa) in maize-wheat cropping system (MWCS) in coastal saline-alkali soil

Sodium carboxymethyl cellulose (CMCNa) application has been a promising approach to improve soil quality. The purpose of this study was to explore the effects of CMC-Na on soil infiltration, evaporation, water-salt distribution, crop growth, water use efficiency and net profit (Net) in a coastal saline-alkali soil maize-wheat cropping system (MWCS). Five CMC-Na application amounts (0, 0.1, 0.2, 0.4 and 0.6 g kg(-1)) were designed for the soil column experiment indoor, and five CMC-Na application amounts were used in 2019-2020 field experiment (CK: 0, C10: 10 kg ha(-1), C20: 10 kg ha(-1), C30: 10 kg ha(-1) and C50: 10 kg ha(-1)), No treatment will be applied in 2021. The results showed that (1) CMC-Na treatment reduced soil cumulative infiltration, infiltration rate, daily evaporation, and cumulative evaporation. (2) After the application of CMCNa, the average soil water storage (SWS) in the 0-60 cm soil layer increased, and soil salinity (SSC) decreased in most treatments. (3) In the 2019-2020, the maize aboveground biomass (B), yield (Y) and water use efficiency (WUE) were the highest under the C20 and C30 treatments, which were 15.24 and 15.32 t ha(-1), 5.67 and 5.49 t ha(-1) and 1.74 and 1.52 kg ha(-1) mm(-1), respectively, and the wheat under C30 treatment is the highest, which were 10.98 t ha(-1), 5.27 t ha(-1) and 1.78 kg ha(-1) mm(-1). (4) A dose of 25.5 kg ha(-1) and 38.9 kg ha(-1) was recommended as the most optimal CMC-Na application for maize and wheat in coastal saline alkali soil, respectively.