Soil erosion is a significant challenge for agricultural regions, with cascading impacts to waterways, land productivity, soil carbon, and ecological health. We provide the first national-scale soil erosion model that incorporates the impacts of grazing on ground cover (C_gr) and soil erodibility (K_tr) into the RUSLE framework. Surface erosion rates for winter-forage paddocks (11 t ha⁻¹ y⁻¹) were substantially higher than pastoral grasslands (0.83 t ha⁻¹ y⁻¹), woody grasslands (0.098 t ha⁻¹ y⁻¹), forests (0.103 t ha⁻¹ y⁻¹) and natural soil production rates (≤1–2 t ha⁻¹ y⁻¹). Validation with empirical measurements from sediment traps, sediment cores, and chemical fingerprinting demonstrated strong linear regressions (r² = 0.86). Terrain impacted soil erosion directly through slope steepness and flow convergence and indirectly through strong orographic effects on rainfall erosivity (r² = 0.39–0.83). Annual surface erosion across Aotearoa New Zealand could reach 16.5-29.2 Mt y⁻¹, representing ∼$20M annually and up to 24–31% of sediment yield for two catchments.

土壤侵蚀是农业地区面临的重大挑战，对水道、土地生产力、土壤碳和生态健康产生连锁影响。我们提供了第一个全国范围的土壤侵蚀模型，该模型将放牧对地被植物(C _gr ) 和土壤可蚀性 (K _tr ) 的影响纳入 RUSLE 框架。冬季牧草围场 (11 t ha ^-1 y ^-1 ) 的表面侵蚀率明显高于牧区草地 (0.83 t ha ^-1 y ^-1 )、木本草地 (0.098 t ha ^-1 y ^-1 )、森林 ( 0.103 t ha ^-1 y ^-1 ) 和自然土壤生产率 (≤1–2 t ha ^-1y ^-1 )。对沉积物圈闭、沉积物岩心和化学指纹的经验测量的验证证明了强线性回归 (r ²  = 0.86)。地形通过坡度陡度和水流汇聚直接影响土壤侵蚀，并通过对降雨侵蚀力的强烈地形影响间接影响土壤侵蚀（r ²  = 0.39-0.83）。新西兰 Aotearoa 的年地表侵蚀量可能达到 16.5-29.2 Mt y ^-1，相当于每年约 2000 万美元，两个流域的沉积物产量高达 24-31%。