Soil Compressibility and Resilience Based on Uniaxial Compression Loading Test in Response to Soil Water Suction and Soil Organic Matter Content in Northeast China

Due to the widespread use of heavy machinery, improper soil tillage practices, and insufficient soil organic materials input, soil compaction has become a major issue affecting soil function in modern agriculture and the sustainability of the environment. The aim of the present study was to evaluate the responses of soil mechanical parameters to soil water content and soil organic matter content (SOM), and to investigate the physical properties of nine disturbed soils in a black soil region in Northeast China. The soil samples were capillary saturated and subjected to 6, 10, 100, 600, and 800 kPa soil water suction (SWS), and pre-compression stress (sigma(p)), compression index (C-c), and decompression index (D-c) were measured. SWS and SOM, and their interaction, significantly influenced the mechanical parameters. sigma(p) increased with an increase in SWS until 600 kPa, while D-c exhibited an opposite trend with an increase in SWS. C-c had a peak value at SWS of 100 kPa. All mechanical parameter values were higher under high SOM than under low SOM. sigma(p), C-c, and D-c were influenced variably by different soil physicochemical factors. Structural equation modeling results revealed that soil mechanical parameters were directly and indirectly influenced by soil texture and mean weight diameter of aggregates, in addition to SOM and SWS. According to the results of the present study, based on soil mechanical and physical properties, increasing SOM and ensuring suitable soil water content during tillage could be applied as management strategies to minimize further soil compaction and improve soil resilience, and thus promote the sustainable development of agriculture in Northeast China.