Soil quality assessment and constraint diagnosis of salinized farmland in the Yellow River irrigation area in northwestern China

• Published in: Geoderma Regional 2023-09, Vol.34, p.e00684, Article e00684
• Main Authors: Zhang, Junhua, Ding, Qidong, Wang, Yijing, He, Mengyuan, Jia, Keli
• Format: Article
• Language: English
• Subjects: agricultural land; cation exchange capacity; China; data collection; electrical conductivity; Integrated quality index; irrigation; Linear scoring; Minimum data set; Nonlinear scoring; salt stress; sand fraction; Soil constraint; soil quality; soil texture; Solonchaks; Solonetzs; total nitrogen; Yellow River
• ISSN: 2352-0094; 2352-0094
• DOI: 10.1016/j.geodrs.2023.e00684

The widespread occurrence of saline soils in arid and semi-arid agricultural regions necessitates the development of simple and practical methods for assessing soil quality in salinized farmland where soil constraints vary depending on farmland type. Herein six different salinized farmland types were selected from the Hetao Plain irrigation area in the upper reaches of the Yellow River plain (Ningxia, China) to assess the soil quality and diagnose potential soil constraints. An integrated quality index (IQI) was calculated using four combinations of nonlinear scoring (SNL) and linear scoring (SL) functions with the total data set (TDS) and minimum data set (MDS) methods. Sixteen indicators of soil physical and chemical properties were included in the TDS, seven of which were selected as MDS indicators, including sand content, total nitrogen, electrical conductivity, and cation exchange capacity. IQI values derived from the MDS method mirrored the results from the TDS method. The soil quality assessed by the four different methods showed consistent spatial patterns across the six farmland types, despite differences in details. In most cases, the highest IQI values were obtained based on TDS-SL, whereas MDS-SL yielded the lowest IQI values. Compared with the results of MDS-SL, IQI values derived from MDS-SNL were closer to those from TDS-SNL. When assessed using the MDS-SNL method, medium- and low-quality soils accounted for >98.0% of Calcic Solonchaks and Takyr Solonetzs. Fluvic Solonchaks had the largest proportion of medium-quality soils (86.5%). The major soil constraint was soil texture for Calcic Solonchaks and Haplic Solonchaks, nutrient limitation for Takyr Solonetzs, saline stress for Haplic Solonetzs, and co-existing soil texture and nutrient limitation for Fluvic Solonchaks and Stagnic Solonchaks. This study unravels multiple soil constraints across various salinized farmland types with medium-to-low soil quality in a major commercial grain base in northwestern China. MDS-SNL-based IQI can be useful for large-scale soil quality assessment in salinized farmland in the Yellow River irrigation area. •The total data set included twenty-four physicochemical indicators of soil.•Seven of which were selected as minimum data set indicators.•Soil quality derived from the minimum data set mirrored the results from the total.•Medium- and low-quality soils accounted for >90.39% of all studied farmland.•The major soil constraints were different about six differ