Impacts of tillage on soil properties and interactions with drainage when reseeding permanent pasture

Abstract Background Grassland reseeding typically requires intensive tillage. This disrupts soil nutrient dynamics, especially under varying drainage conditions. Methods This study evaluated the combined effects of tillage legacy, drainage and soil depth on key soil properties within a long‐term grassland experiment. Treatments compared two no‐tillage durations (5 years of no tillage, 5YNT; 30 years of no tillage, 30YNT), two drainage systems (drained and undrained) and two depths (0–10 and 10–30 cm) following reseeding. Total carbon (TC), total nitrogen (TN), total phosphorus (TP) and pH were measured. Results Significant three‐way interactions were detected for all variables. At 0–10 cm, undrained 30YNT plots showed 69% greater TC and 66.9% higher TP than the lowest values recorded in 5YNT × drained combinations at 10–30 cm. TN followed a similar pattern, with substantial enrichment under long‐term no‐tillage. Reseeding reduced TC, TN and TP within 5 years, particularly in surface soils, with the largest proportional losses in undrained plots where nutrient concentrations had been high prior to tillage. Conclusions Findings highlight the importance of conserving long‐term no‐tillage systems to enhance nutrient retention and promote sustainable grassland productivity. Conventional tillage of nutrient‐rich pastures should be avoided to prevent major nutrient losses.