An evaluation framework for identifying saline croplands for improvement: A case study of Songnen Plain

Land salinisation in the Songnen Plain is a serious constraint to agricultural development. Assessing and identifying saline land as having advantages for improvement is of great significance for improving the efficiency of saline croplands improvement. Taking the western Songnen Plain as the study area, an evaluation framework for identifying saline-alkali croplands for improvement was proposed. Compared with traditional research models that evaluate the degree of saline-alkali land suitable for farming, the purpose of this study is to identify land that is easier to improve and has more or more value for farming. On the basis of evaluating the suitability of saline-alkali land using the Analytic Hierarchy Process-Geographic Information System (AHP-GIS) model, this framework incorporates the degree of soil salinisation, quantified by electrical conductivity and exchangeable sodium percentage, and hydrological connectivity, calculated based on terrain factors and vegetation cover., constructs a saline-alkali land improvement index, and divides suitable improvement areas at different levels. The results indicate that the northern part of the study area exhibits low cropland suitability value, primarily due to higher pH values, unfavorable topography, and lower temperatures. Extreme salinity area are concentrated in the central part of the study area, mainly due to elevated soil conductivity and exchangeable sodium percentages. Areas with high hydrological connectivity value are distributed in the northern, southern, and eastern parts, owing to the presence of numerous lakes and dense vegetation cover. Using the Suitable Improvement Index (SII), 39.42 % of the croplands were identified as suitable for improvement. Among these, low-value, moderate-value, and high-value accounted for approximately 5.43 %, 33.36 %, and 61.21 % of SII subareas. The low SII values are found in Qianan and Tongyu in the southern and central parts of the study area, while high SII values are distributed in Tongyu, Daan, and Taobei in the central part of the study area. The evaluation framework of this study identifies saline-alkali croplands that is more suitable for improvement, providing valuable insights into the restoration of saline-alkali croplands in Northeast China. We provides valuable insights into saline-alkali land restoration from a management and strategic perspective.