The Century model was used to simulate soil C and N cycling and crop production dynamics in an ongoing field experiment in Uruguay (started in 1963). The model was calibrated using observed data from three treatments (crop or crop–pasture rotations) and validated with a fourth treatment. The model correctly predicted the impact of different treatments on microbial biomass, N mineralization, soil respiration, and crop yields. The model and observed data show that soil respiration, N mineralization, soil C, and crop yields increase with increasing plant‐derived C inputs caused by increasing the frequency of pastures in the rotations. This is one of the first papers that show the strong positive correlation of observed soil C with plant C soil inputs to field‐observed microbial biomass, soil respiration, and N mineralization. The results also showed that reducing tillage and transitioning to a no‐till system increased soil C and reduced soil erosion. The main path of soil C losses was heterotrophic microbial respiration, which accounted for 66% of the total C lost in a continuous crop rotation and no fertilizers, 71% in a continuous crop rotation with fertilizers, and 86% in a crop–pasture rotation with fertilizers. Model results from a degraded cropping system showed that adding grass–clover (Trifolium spp.) pastures greatly increased plant production and soil C, whereas reducing the frequency of grass–clover pastures in high‐fertility cropping systems from 50% of the time to 25% reduces crop yields and soil C. Including cover crops substantially increases crop production and maintains soil C in high‐fertility and degraded cropping systems.

中文翻译：

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南美南部五十年田间试验的农作物轮作生态系统动态：世纪模型和田间结果

在乌拉圭正在进行的田间试验（始于1963年）中，使用Century模型来模拟土壤C和N循环以及作物生产动态。使用来自三种处理（作物或作物-牧草轮作）的观察数据对模型进行校准，并通过第四种处理进行验证。该模型正确预测了不同处理对微生物生物量，氮矿化，土壤呼吸和农作物产量的影响。该模型和观察到的数据表明，由于轮作牧场频率的增加，土壤呼吸，氮矿化，土壤碳和农作物产量随植物源碳输入的增加而增加。这是第一批表明观测到的土壤C与植物C的土壤输入与实地观察到的微生物量，土壤呼吸和N矿化之间呈强正相关的论文之一。结果还表明，减少耕作并过渡到免耕系统增加了土壤碳含量，并减少了土壤侵蚀。土壤碳损失的主要途径是异养微生物呼吸，占连续轮作和不施肥的总碳损失的66％，连续轮作和肥料的71％，作物-牧草轮作的总碳损失的86％。与肥料。退化的耕作系统的模型结果表明，添加草三叶草（Trifolium spp。）牧草极大地提高了植物产量和土壤碳，而将高肥力种植系统中草三叶草牧草的频率从50％减少到25％会降低作物产量和土壤C。包括掩盖作物可大大增加作物的收成在高肥力和退化的耕作系统中生产和维持土壤碳。