Objective Due to the combined effects of human activities and natural factors, soil and water loss in the black soil region is becoming increasingly severe, with gully erosion being the most severe form. Gully erosion not only leads to the loss of black soil resources and a decline in crop yields, but also causes deterioration of soil ecological functions, posing a threat to national food security and ecological balance.

Methods To investigate the variation patterns of soil nutrients in erosion gullies on sloping farmland with different treatment durations, this study selected erosion gullies treated for 2 and 7 years as study subjects, with developing gullies serving as controls. Soil samples were collected from the gully slopes and gully bottoms using the diagonal sampling method, and nutrients were measured. Correlation analysis and principal component analysis were applied to elucidate the variation patterns of soil nutrients in the 2-year and 7-year treated gullies.

Results 1) Compared with the developing gully, the mass fractions of soil organic matter, total nitrogen, alkali-hydrolyzable nitrogen, total phosphorus, available phosphorus, total potassium, and available potassium in the erosion gullies treated for 2 and 7 years were all significantly higher (P < 0.05). 2) There was a significant positive correlation among the various nutrient indicators, and the correlation coefficients increased with increasing treatment duration. 3) The comprehensive evaluation scores from principal component analysis were, in descending order: 7-year treated gully (2.303) > 2-year treated gully (1.747) > developing gully (0.873), indicating that a longer treatment duration significantly enhanced the overall recovery level of soil nutrients.

Conclusions Treatment measures can significantly increase soil nutrient content in erosion gullies, and the restoration effect continues to strengthen with increasing treatment duration. Long-term treatment promotes the holistic and synergistic recovery of various soil nutrient indicators. The process of soil nutrient recovery varies markedly across different soil depths, and long-term treatment can effectively improve the profile distribution characteristics of nutrients.