Management intensive grazing (MIG), also known as rotational grazing or multi-paddock grazing, is purported to sequester carbon (C) in soils compared to other agricultural management systems. Prior research examining the potential for MIG to enhance soil C has been inconclusive, and past investigations have not addressed whether higher nitrous oxide (N₂O) emissions may accompany increases in soil C stocks. Here we examined linkages among MIG, soil C accumulation, and N₂O emissions in cool-season, organic pastures of the northeastern United States. We found that pastures under MIG increased soil C concentrations by 11% from 0–15 cm depth but that soil C stocks at all sampled depths did not differ between hayed and grazed fields. We observed a divergent response in soil N to MIG, where both N concentrations and stocks significantly increased and the soil C:N ratio significantly decreased in rotationally grazed pastures. Our results also demonstrated that during the second year of the study, N₂O emissions were on average 33% higher in grazed fields and compared to hayed fields. These elevated N₂O fluxes in MIG fields may have offset any soil C gains achieved under MIG, as demonstrated by similar climate forcing values (as CO₂-equivalents) for hayed and grazed pastures over a 100-year time horizon. The significant variation we detected among farms in soil C and N stocks, soil microbial activity, plant biomass production, and soil greenhouse gas emissions demonstrates that MIG does not have uniform effects across the landscape. Overall, our study demonstrates that care should be taken when promoting management practices that may have unintended climate consequences.

与其他农业管理系统相比，管理密集型放牧（MIG），也称为轮牧或多围场放牧，据称可以隔离土壤中的碳（C）。先前的研究尚未证实MIG可以提高土壤C的潜力，并且过去的研究尚未解决更高的一氧化二氮（N ₂ O）排放是否可能伴随土壤C储量的增加。在这里，我们研究了MIG，土壤C积累和N _{2之间的联系。}美国东北部凉爽季节的有机牧场中的O排放。我们发现，MIG下的牧草在0至15 cm的深度处将土壤C的浓度提高了11％，但是在所有采样深度的土壤C的存量在干草和草场之间没有差异。我们观察到土壤N对MIG的反应不同，在旋转放牧的牧草中，N的含量和储量均显着增加，土壤C：N的比例显着下降。我们的结果还表明，在研究的第二年中，放牧田地和干草田相比，N ₂ O排放平均高出33％。MIG场中这些升高的N ₂ O通量可能抵消了在MIG下获得的任何土壤C增幅，如相似的气候强迫值（以CO ₂-等价物）用于100年时间范围内的干草和放牧牧场。我们在农场的土壤碳和氮储量，土壤微生物活性，植物生物量生产和土壤温室气体排放量之间发现了显着差异，这表明MIG在整个景观中的影响并不均匀。总体而言，我们的研究表明，在推广可能会对气候造成意外影响的管理实践时应格外小心。