Abstract: Based on an understanding of the differences in salt composition and nutrient availability, saline-alkali land improvement can be carried out to specifically improve the soil environment of saline-alkali land and increase crop yields. The objective of this study was to select an appropriate treatment of fertilizer application combined with improvement agents for maize planation in Ningxia, China. Given the unique characteristics of secondary saline-alkali soils in the Northwest Hetao Irrigation District, this study focused on the synergistic regulation of the “amendment-fertilizer-soil-crop” system. It investigated different types of amendment-organic fertilizer application patterns to address three key issues: 1) elucidate the synergistic mechanisms of composite amendments and fertilizer application on soil salinity migration and transformation, and clarify the interactive effects of each component in salinity regulation; 2) Reveal the coupled influence patterns of application patterns on soil physical and chemical properties and corn growth; 3) Select the optimal application scheme suitable for the Hetao Irrigation District, quantify its effect on reducing the annual accumulation rate of soil salinity, and assess its potential for increasing maize yields. This treatment was designed as the combinations of amendments (microbial agents, activated humic acid, and microsilica powder) and different types of fertilizers (conventional chemical fertilizers, organic fertilizers, and amino acid containing fertilizers) with no fertilization as the control. The field experiment of maize was carried out in 2023. Soil pH value, total salt, salt distribution, nutrients, and corn yield were analyzed at different stages of maize. The results showed that: 1) The application of activated humic acid in combination with amino acids can effectively reduce soil pH, alkalinity, and total salt content. Under this treatment, soil fertility levels improved most significantly, with organic matter and alkali-hydrolyzable nitrogen increasing by 80.92% and 86.07%, respectively, compared to pre-improvement levels. Activated humic acid combined with amino acids can improve soil quality by regulating salinity and alkalinity indicators, with Na⁺ and Cl⁻ levels decreasing by 83.34% and 57.27%, respectively, compared to pre-improvement levels. Under this treatment, the maize yield reached 137.77 kg/hm², increased by 3.97% to 29.52% compared to other treatments. 2) The soil quality index was the highest under the treatment of activated humic acid combined with amino acid treatment. This treatment outperformed other treatments in reducing saline-alkali indicators, improving soil fertility, and increasing maize yield. 3) The application of activated humic acid combined with amino acids improved soil quality by reducing soil salinity, increasing soil nutrients, and enhancing soil fertility. In summary, the use of activated humic acid combined with amino acids is recommended as a guideline for improving saline-alkali soils and achieving high maize yields in the study area.