Effects of fertigation with carboxymethyl cellulose potassium on water conservation, salt suppression, and maize growth in salt-affected soil

Soil salinization is a severe problem in arid and semi-arid regions that substantially reduces local agricultural productivity and poses long-term risks to sustainable food production. Traditional soil conditioners and drip irrigation alone fall short in mitigating soil salinity, necessitating the development of more effective soil amendments with higher water retention capacity. This study conducted maize field trials from 2021 to 2022 on loamy alluvial soil in Ningxia, northwest China, aiming to evaluate the impact of three treatments: CK (flood irrigation with irrigation quota of 900 mm), D (drip irrigation with irrigation quota of 450 mm), and DC (drip irrigation with irrigation quota of 450 mm and 300 kg ha1 carboxymethyl cellulose potassium (CMC-K) application). We investigated water-salt transport, soil fertility, and maize growth. The results revealed that a high frequency of drip irrigation significantly reduced surface soil salinity, thereby generating a desalination layer centered on the drip emitters. During the mature stage of maize growth in the second year of the experiment, the D and DC significantly increased soil moisture content by 11.61-20.43% in the 0-40 cm soil depth and reduced soil salinity by 17.50-23.10% compared with CK, yielding an average desalination rate of 23.42%. Compared to D, DC significantly increased soil organic carbon (6.70-44.62%), mineralized nitrogen (11.86-27.42%), effective phosphorus (6.52-65.13%), and soluble potassium (8.64-36.42%), mitigated surface evaporation, curbed groundwater loss, minimized transpiration of maize, and improved water use efficiency of maize cultivation, resulting in a marked 21.29% increase in grain yield. In summary, CMC-K was found to have a pronounced influence on water retention, salinity reduction, and crop productivity, and can be considered a promising novel soil amendment.