Tea plantations cover an area of ca. 31,000 ha in the Central North of Iran. This area, after clearing the original forests more than 50 years ago, became exposed to severe soil erosion. The objective of this study was to assess long-term soil erosion rates in tea farms and to evaluate their soil conservation effect at a whole-of-catchment scale. No previous information on direct measurements of soil erosion in this mountainous tea agro-ecosystem of Northern Iran is available. Point-based estimates of net erosion have been obtained using the ¹³⁷Cs technique and these results were compared with estimates using the RUSLE model. Calculations of soil erosion rates from ¹³⁷Cs inventories, based on the Mass Balance Model II, revealed that 1.3 mm year⁻¹ and 1.45 mm year⁻¹ of soils were lost from the two sub-catchments A1 and A2, into which the catchment can be divided. The annual net erosion rate of the entire catchment was 17.06 t ha⁻¹ year⁻¹ which is consistent with the rate of 20.4 t ha⁻¹ year⁻¹ obtained by the RUSLE model of at the same scale. This study suggests adopting soil conservation practices to control soil erosion, especially after deforestation and periodic pruning of tea bushes. Sustainable land-use plans are then necessary for tea farms of Iran to protect soil resources and to reduce the off-site impacts of land degradation (mainly siltation) on the reservoirs and coastal area.

茶园约占面积。伊朗中北部31,000公顷。在五十多年前砍伐原始森林后，该地区开始遭受严重的土壤侵蚀。这项研究的目的是评估茶园的长期土壤侵蚀率，并在整个集水规模上评估其土壤保护效果。没有关于伊朗北部山区茶农业生态系统中土壤侵蚀直接测量的信息。使用¹³⁷ Cs技术获得了基于点的净侵蚀估计，并将这些结果与使用RUSLE模型的估计进行了比较。根据质量平衡模型II，从¹³⁷ Cs清单进行的土壤侵蚀速率计算表明，1.3 - ¹年^-1从两个子集水区A1和A2损失了1.45 mm年^-1的土壤，可以将集水区分为两个子集水区。整个集水区的年净侵蚀率是17.06 t ha ^-1  year ^-1，这与相同规模的RUSLE模型获得的20.4 t ha ^-1  year ^-1的速率一致。这项研究建议采取土壤保护措施来控制土壤侵蚀，尤其是在森林砍伐和茶树定期修剪之后。因此，伊朗的茶园必须制定可持续的土地利用计划，以保护土壤资源并减少土地退化（主要是淤积）对水库和沿海地区的异地影响。