Abstract

This study evaluated the effect of contrasting land-use systems on changes in pools of total organic carbon (TOC) and its labile fractions, and identified the sensitivity of soil properties as a minimum data set (MDS) for assessing soil quality change in a dry, mountainous Himalayan region in India. The soils under mono (barley/mustard/oats)- and double (barley-buckwheat/barley-turnip)-cropping systems had significantly (p < .05) lower TOC by ∼34 and 20%, while the less labile C (Fract. 3) concentration was lower by ∼46 and 48%, respectively, compared with the agro-forestry (popular/willow). The stable C pool (Fract. 3 + Fract. 4) comprised ∼74, 77, 86, 74 and 73% of TOC in soils under mono-cropping, double-cropping, agro-forestry, orchards and vegetable crops, respectively. Land-use significantly impacts the sensitivity of labile C fractions, viz. water extractable organic C (WEOC), microbial biomass C (MBC) and organic C fractions of variable oxidizability (i.e. Fract. 1, Fract. 2, Fract. 3 and Fract. 4). The sensitivity analysis showed a change of ∼21.5–56.2% in the TOC pool, with the highest change for soils under vegetable crops and the lowest for double-cropping. Soil protein exhibited a significant relationship with TOC and its fractions, enzymatic and biochemical properties, and soils’ fine fraction (silt and clay). The stable C pool exhibited a significant linear relationship with soils’ finer fraction (silt = 0.82**; clay = 0.78**, p < .01), indicating that the mineral matrix had a profound influence on C stabilization in soils. The land-use systems with higher soil total glomalin (TG) content had higher moisture retention capacity and stable C pool. The principal component analysis (PCA) identified TG, Fract. 3 and available-K as most important soil quality indicators for discriminating change in soil health in a cold, dry Himalayan region.

摘要

本研究评估了对比土地利用系统对总有机碳 (TOC) 库及其不稳定部分变化的影响，并将土壤特性的敏感性确定为评估干旱地区土壤质量变化的最小数据集 (MDS) ，印度喜马拉雅山区。单（大麦/芥末/燕麦）和双（大麦-荞麦/大麦-萝卜）种植系统下的土壤具有显着的 ( p < .05) 将 TOC 降低 ∼34% 和 20%，而较不稳定的 C (Fract. 3) 浓度分别降低 ∼46% 和 48%，与农林业（流行/柳树）相比。稳定的碳库（Fract. 3 + Fract. 4）分别在单作、双作、农林业、果园和蔬菜作物的土壤中占 TOC 的 74%、77%、86%、74% 和 73%。土地利用显着影响不稳定 C 组分的敏感性，即。水可萃取有机碳 (WEOC)、微生物生物质碳 (MBC) 和可变氧化性有机碳馏分（即馏分 1、馏分 2、馏分 3 和馏分 4）。敏感性分析显示，TOC 池的变化约为 21.5-56.2%，其中蔬菜作物下的土壤变化最大，双熟土壤的变化最小。土壤蛋白质与 TOC 及其组分有显着关系，酶学和生化特性，以及土壤的细小部分（淤泥和粘土）。稳定的 C 库与土壤的细小部分（淤泥 = 0.82**；粘土 = 0.78**，p  < .01），表明矿物基质对土壤中的碳稳定性有深远的影响。土壤总glomalin（TG）含量较高的土地利用系统具有较高的保水能力和稳定的C库。主成分分析 (PCA) 确定了 TG、Fract。3 和速效钾作为区分寒冷干燥喜马拉雅地区土壤健康变化的最重要土壤质量指标。