S-metolachlor is a widely used herbicide that may contaminate groundwater when applied to irrigated crops, especially when the soil has a low organic carbon (OC) content. The objective here was to assess the capacity of two organic wastes, namely, green compost (GC) and pelletised organo-mineral manure fertilizer (PM), applied to two soils (S) with different textures at a rate of 10% dry weight to modify the fate of S-metolachlor. The herbicide's Freundlich adsorption coefficient (Kf) increased within a range of 3.2–8.2 times in S + GC and 3.8–6.8 times in S + PM. A positive correlation between adsorption and OC and the coefficient of variation of the OC normalised adsorption coefficients (Kf_oc) higher than 20% indicated the evident influence on this process of soil OC content and its nature. The increase in adsorption did not prevent the dissipation of S-metolachlor in the amended soils, although the degradation rate decreased up to ~2 times or was not significantly modified across the different soil types. The S-metolachlor metabolites, metolachlor ethane sulfonic acid and metolachlor oxanilic acid, were detected in the herbicide's dissipation in the unamended soils, but they were not detected in the amended soils. The mobility experiments indicated leached amounts of S-metolachlor higher than 50% in unamended soil. The amounts decreased 1.1–1.7 times and 1.7–1.8 times in the S + GC and S + PM when a saturated flow was applied. Moreover, breakthrough curves indicated a slow leaching kinetics of herbicide in amended soils, with low concentrations continuously detected in the leachates together with a decrease in the maximum peak concentration. The results show the effect of the application of organic wastes especially in sandy soils to promote the immobilisation and/or degradation of S-metolachlor, avoiding its transfer to other environmental compartments.

S-异丙甲草胺是一种广泛使用的除草剂，在用于灌溉作物时，特别是在土壤中有机碳（OC）含量较低的情况下，可能会污染地下水。此处的目的是评估两种有机废物的容量，即绿色堆肥（GC）和颗粒状有机矿物肥料（PM），以10％的干重比施用于具有不同质地的两种土壤（S）的能力。改变甲草胺的命运。除草剂的Freundlich吸附系数（Kf）在S + GC中增加了3.2–8.2倍，在S + PM中增加了3.8–6.8倍。吸附和OC之间的正相关性与OC归一化吸附系数的变化系数（Kf _oc）高于20％表示对该过程中土壤OC含量及其性质具有明显影响。吸附量的增加并不能阻止S-甲草胺在改良土壤中的消散，尽管降解速率降低了约2倍，或者在不同土壤类型中没有明显改变。在未经改良的土壤中除草剂的消散中检测到了S-甲草胺代谢产物，甲乙草胺乙烷磺酸和甲草胺草酰苯胺酸，但在经修正的土壤中未检测到它们。流动性实验表明，未经改良的土壤中的异丙甲草胺的浸出量高于50％。当施加饱和流量时，S + GC和S + PM中的量减少了1.1–1.7倍和1.7–1.8倍。此外，突破曲线表明除草剂在改良土壤中的浸出动力学较慢，在浸出液中连续检测到低浓度，同时最大峰值浓度降低。结果表明，特别是在沙质土壤中施用有机废物，可促进S-异丙甲草胺的固定和/或降解，避免其转移到其他环境隔室中。