Background Soil organic carbon (SOC) is key indicator of soil quality and health. It has substantial benefits to the ecosystem. Information on the magnitude of carbon pools under field scale of subsistence farms is scanty. This study aimed to assess carbon stock, sequestration and soil properties among different fields in smallholder farms of southern Ethiopia. Five field types within a farm were investigated viz. coffee ( Coffea arabica L.), enset (Ensete ventricosum), root and tuber crop field (RTC), crop field used for growing cereals and pulses, and fallow land. For each field, eight representative fields as a replication were selected. Surface soil samples were collected, and analyzed to determine soil physico-chemical properties. In addition, C stock, C-sequestration, and CO 2 emission were also evaluated. Results The result regarding soil properties revealed significant differences in almost all of investigated parameters. The minimum and maximum values being recorded were: bulk density (BD) (1.05, 1.29 gm cm −3 ), pH (6.1, 7.0), SOC (1.1, 2.48%), TN (0.09–0.19%), available P (1.1, 70.9 mg/kg), total exchangeable bases (9.5, 20.5 Cmolc/kg), K/Mg (0.37,1.02), B (0.4, 1.2 mg/kg) Cu (0.32, 0.91 mg/kg), Zn (5, 20.5 mg/kg), Fe (105.5, 133.8 mg/kg) and CEC (18.6, 27.5 mg/kg). Fields in the backyard (enset and coffee) showed lowest BD and maximum values of soil chemical properties. On contrary, highest BD and lowest values of chemical parameters were observed in crop and fallow fields. The result further indicated that the field that stocked and sequestered more carbon, and emitted less CO 2 was coffee > enset > RTC > crop field > fallow land. C-stock and sequestration (t/ha) magnitude was being: coffee (81.4, 298.5), enset (75.5, 277.0), RTC (68.8, 252.6), crop field (57.5, 211.0) and fallow (43.3, 159). Using coffee field as least CO 2 emitter and as the base value for comparison, the percentage increment in CO 2 emission out of the sequestered carbon was 7.2% (enset), 15.4% (RTC), 29.3% (crop field) and 46.7% (fallow).Soil deterioration index (%) relative to coffee field for OC, N, P, and K in their order was as follows: enset [− 2.8, 0, 254.5, 23.1], RTC [− 17.7, − 31.6, − 59.5, − 34.6], crop field [− 35, − 47.4,− 79, − 46] and fallow [− 55.7, − 52.6, − 94.5, and − 76.9]. Conclusion Different fields within smallholder farms exhibited significant variation in amount of carbon sequestered, CO 2 emission, soil degradation and soil properties. Thus, climate smart soil management practices that would enhance carbon pool and simultaneously increasing soil quality are suggested e.g., integrated nutrient management.

中文翻译：

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埃塞俄比亚南部小农农场田间的碳储量、封存和土壤特性

背景 土壤有机碳 (SOC) 是土壤质量和健康的关键指标。它对生态系统有很大的好处。关于自给农场田间规模的碳库规模的信息很少。本研究旨在评估埃塞俄比亚南部小农农场不同田间的碳储量、固存和土壤特性。调查了农场内的五种田地类型，即。咖啡 (Coffea arabica L.)、enset (Ensete ventricosum)、块根和块茎作物田 (RTC)、用于种植谷物和豆类的作物田以及休耕地。对于每个字段，选择八个代表性字段作为复制。收集表层土壤样品并进行分析以确定土壤理化特性。此外，还评估了 C 储量、C 封存和 CO 2 排放。结果 关于土壤性质的结果显示，几乎所有调查参数都存在显着差异。记录的最小值和最大值是：体积密度 (BD) (1.05, 1.29 gm cm -3 )、pH (6.1, 7.0)、SOC (1.1, 2.48%)、TN (0.09–0.19%)、可用 P ( 1.1, 70.9 mg/kg), 总可交换碱 (9.5, 20.5 Cmolc/kg), K/Mg (0.37,1.02), B (0.4, 1.2 mg/kg) Cu (0.32, 0.91 mg/kg), Zn ( 5, 20.5 mg/kg), Fe (105.5, 133.8 mg/kg) 和 CEC (18.6, 27.5 mg/kg)。后院的田地（enset 和咖啡）显示土壤化学性质的最低 BD 和最大值。相反，在作物和休耕地中观察到最高的 BD 和最低的化学参数值。结果进一步表明，储存和封存更多碳、排放较少CO 2 的田地是咖啡> enset > RTC > 农田> 休耕地。C 储量和封存 (t/ha) 量级为：咖啡 (81.4, 298.5)、enset (75.5, 277.0)、RTC (68.8, 252.6)、农田 (57.5, 211.0) 和休耕 (43.3, 159)。以咖啡田作为最低的 CO 2 排放量并作为比较基准值，固碳中 CO 2 排放的百分比增量为 7.2%（enset）、15.4%（RTC）、29.3%（作物田）和 46.7% （休耕）。 OC、N、P 和 K 相对于咖啡田的土壤退化指数 (%) 依次为：enset [− 2.8, 0, 254.5, 23.1], RTC [− 17.7, − 31.6, − 59.5, − 34.6]，作物田地 [− 35, − 47.4, − 79, − 46] 和休耕地 [− 55.7, − 52.6, − 94.5, 和 − 76.9]。结论 小农农场内的不同田地在固碳量、CO 2 排放、土壤退化和土壤性质方面表现出显着差异。因此，