This study aims to develop water-saving, alkalinity-reducing, and soil fertility-enhancing techniques to provide technical support for the efficient utilization of heavily saline-alkaline areas in Ningxia. To address issues of dual salinity and alkalinity, limited freshwater resources, and difficulties in crop growth in arid regions, four organic materials—organic fertilizer, maize straw, furfural residue, and biochar—were selected for combination with desulfurization gypsum. Additionally, a control treatment without any improvement materials was established for comparative analysis. The effects of gypsum combined with organic materials on the properties of alkaline saline soils and maize growth under brackish water drip irrigation conditions were evaluated through a series of bucket cultivation experiments conducted in Huinong District, Ningxia. The findings revealed that (1) the application of gypsum enhanced exchangeable calcium content and significantly lowered electrical conductivity (by 28.3% to 57.9%) and pH. It also led to significant reductions in total nitrogen, alkaline-hydrolysis nitrogen, rapidly available potassium, and organic carbon. However, in the spring of the second year, soil electrical conductivity increased, while available phosphorus content declined. (2) The combination of gypsum and organic fertilizer with 0.56% furfural residue or biochar further reduced soil electrical conductivity and increased exchangeable calcium content, while maintaining total nitrogen and available potassium contents. This combination significantly enhanced organic carbon, alkaline-hydrolysis nitrogen, and available phosphorus contents in the soil. (3) The addition of 0.56% furfural residue combined with gypsum and organic fertilizer significantly mitigated soil salinity and alkalinity in the following year, while markedly enhancing soil organic carbon, total nitrogen, available phosphorus, and cation exchange capacity. This combination also notably enhanced the height and stem diameter of maize plants, ultimately resulting in increased maize biomass. Given that furfural residue offers better economic advantages than biochar. Therefore, the application of desulfurization gypsum combined with organic fertilizer and furfural residue is suitable for improving alkalize solonchaks soil.