Evaluating black soil thickness under straw return practices by using ground penetrating radar

The intensive utilization and erosion-induced thinning of global black soil threaten its sustainable use, making accurate thickness assessment crucial. This study aimed to evaluate the impact of straw return practices on the accuracy of Ground Penetrating Radar (GPR) for measuring black soil thickness. Indoor simulation experiments were conducted with varying soil bulk density (1.1 g cm -3 , 1.3 g cm -3 , and 1.5 g cm -3 ), moisture contents (10%, 20%, 30%), and straw application methods (mulched or incorporated at 50% and 100% rates). The results indicated that soil permittivity generally increased with moisture under both straw treatments. While permittivity increased with bulk density under straw mulching, it responded variably under incorporation (slight increase at 50% rate but decrease at 100%). GPR overall achieved an accuracy of 86.5%-93.8%%. It proved effective under straw-incorporated conditions,but had limited effectiveness under low bulk density and moisture content in the straw-mulched treatment. Field measurements revealed average thicknesses of 29.1 cm (bare slope), 28.6 cm (straw-mulched slope), and 34.6 cm (straw-incorporated slope), with distinct distribution patterns along slopes. This study clarified the applicable range and precision of GPR for measuring black soil thickness under straw return and provided scientific and technological support for sustainable black soil management.