The expansion of oil palm (Elaeis guineensis Jacq.) cultivation in degraded areas has increased in the Brazilian Amazon. Cultivation of oil palm in diversified agroforestry systems may be a relatively sustainable alternative to monocultures for crop expansion. Here, we evaluated the effect of oil palm cultivation systems on soil C, an important indicator of the soil quality of production systems. We assessed: (1) whether these systems of oil palm cultivation alter the potassium permanganate oxidizable C content (POx-C) and the carbon management index (CMI); and (2) how the POx-C varied among management zones (harvest path, leaf pile, weeded circle, and diversified strip). The soil C indices of the oil palm cultivation systems were also compared with those of secondary forests. POx-C varied consistently based on the pattern agroforestry > secondary forest = monoculture, ranging from 0.95 ± 0.14 (agroforestry) to 0.66 ± 0.10 g·kg⁻¹ (monoculture). The POx-C pattern among management zones was pile > diversified strip = weeded circle > harvest path. The CMI was higher in agroforestry than in monoculture. We found that these indices are sensitive to land-use systems and management practices that affect organic matter input. Organic fertilization and species diversity likely drive the improvement of soil quality in agroforestry systems than in monocultures through C input to the soil directly and indirectly, by creating favorable conditions for the action of root and fauna that in turn positively affect soil C. Therefore, we postulate that soil quality improves through oil palm agroforestry than through oil palm monocultures.

中文翻译：

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油棕农林比亚马逊东部的单一种植园显示出更高的土壤高锰酸盐可氧化碳

油棕（Elaeis guineensis）的扩张Jacq.) 在巴西亚马逊地区退化地区的种植有所增加。在多样化的农林业系统中种植油棕可能是一种相对可持续的替代单一栽培的作物扩张方式。在这里，我们评估了油棕种植系统对土壤碳的影响，这是生产系统土壤质量的重要指标。我们评估了：（1）这些油棕种植系统是否会改变高锰酸钾可氧化碳含量（POx-C）和碳管理指数（CMI）；(2) POx-C 在管理区（收获路径、叶堆、杂草圈和多样化带）之间的变化情况。油棕种植系统的土壤碳指数也与次生林的土壤碳指数进行了比较。POx-C 根据农林业 > 次生林 = 单一栽培的模式一致变化，范围从 0。⁻¹（单一栽培）。管理区的POx-C模式为桩>多样化条带=杂草圈>收获路径。农林业的 CMI 高于单一栽培。我们发现这些指数对影响有机物质输入的土地利用系统和管理实践很敏感。有机施肥和物种多样性可能通过直接或间接向土壤输入碳，为根和动物群的作用创造有利条件，进而对土壤碳产生积极影响，从而推动农林业系统中土壤质量的改善，而不是单一栽培系统。 因此，我们假设土壤质量通过油棕农林业改善而不是通过油棕单一栽培。