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首页> 外文期刊>Applied radiation and isotopes: including data, instrumentation and methods for use in agriculture, industry and medicine >(137)Cs tracing dynamics of soil erosion, organic carbon and nitrogen in sloping farmland converted from original grassland in Tibetan plateau.
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(137)Cs tracing dynamics of soil erosion, organic carbon and nitrogen in sloping farmland converted from original grassland in Tibetan plateau.

机译：（137）Cs追踪从青藏高原原始草地转化为坡耕地的土壤侵蚀，有机碳和氮的动态。

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摘要

There is a shortage of research concerning the relationships between land-use change, soil erosion, and soil organic carbon (SOC) and nitrogen (N) dynamics in alpine environments such as those found in the Tibetan plateau. In this paper, typical sloping farmlands converted from grassland 50 years ago in eastern Tibet were selected to determine dynamics of soil erosion, SOC, and total N associated with land-use change. Soil samples were collected from sloping farmland and control fields (grassland). The (137)Cs, SOC, total N contents, and soil particle size fractions were analyzed in these samples. As compared with the control fields, (137)Cs, SOC, and total N inventories in the sloping farmlands decreased by 30%, 27%, and 33%, respectively. Meanwhile variations in the three parameters were enhanced in the sloping farmlands, with coefficients of variation (CVs) of 38%, 23%, and 20%, respectively, for (37)Cs, SOC, and total N. In addition, SOC and total N inventories significantly decreased with increasing soil erosion in the sloping farmland. In a sloping farmland with a steep 24 degrees gradient, the (137)Cs inventory gradually increased along a downslope transect with its lowest value at 0Bqm(-2) in the top-slope position (0m). The soil clay (<0.002mm) content in such an area increased with decreasing elevation (r=-0.95, p=0.001). Significant correlations between (137)Cs and clay (r=0.92, p=0.003), SOC (r=0.96, p=0.001), or total N (r=0.95, p=0.001) were also found in the farmland. These results showed that converting alpine grassland to sloping farmland accelerates soil erosion, losses in SOC and N, and increases the soil's spatial variability. The combined impacts of tillage and water erosion contributed a significant decrease in the soil's organic carbon and N storages. Particularly in steep sloping farmlands, tillage erosion contributed for severe soil loss, but the soil redistribution pattern was dominated by water erosion, not tillage erosion, due to the lack of boundaries across the field patches. It was also found that (137)Cs, SOC, and total N moved along the same pathway within these sloping farmlands, resulting in net C and N losses during soil redistribution. The negative influences of land-use conversion from grassland to farmland in sloping areas in the Tibetan plateau should be addressed.
机译：在诸如青藏高原的高山环境中，关于土地利用变化，土壤侵蚀以及土壤有机碳（SOC）和氮（N）动态之间关系的研究不足。本文选择了50年前西藏东部典型的由草地改建的坡耕地，以确定与土地利用变化相关的土壤侵蚀，SOC和总氮的动态变化。从倾斜的农田和对照田地（草地）收集土壤样品。在这些样品中分析了（137）Cs，SOC，总氮含量和土壤粒径分数。与控制田相比，坡耕地的（137）Cs，SOC和总氮库存分别减少了30％，27％和33％。同时，在倾斜的农田中，这三个参数的差异有所增加，（37）C，SOC和总氮的变异系数（CV）分别为38％，23％和20％。随着坡耕地土壤侵蚀的增加，总氮库存显着下降。在倾斜度为24度的倾斜农田中，（137）Cs量沿下坡样带逐渐增加，其最低值为0Bqm（-2），位于上坡位置（0m）。在该区域中，土壤粘土（<0.002mm）含量随海拔降低而增加（r = -0.95，p = 0.001）。在农田中也发现了（137）Cs与粘土（r = 0.92，p = 0.003），SOC（r = 0.96，p = 0.001）或总氮（r = 0.95，p = 0.001）之间的显着相关性。这些结果表明，将高寒草地转变为坡耕地会加速土壤侵蚀，土壤有机碳和氮的流失，并增加土壤的空间变异性。耕作和水蚀的综合影响大大降低了土壤的有机碳和氮储量。特别是在陡坡耕地中，耕作侵蚀造成了严重的土壤流失，但由于田间地块缺乏边界，土壤的重新分配方式主要是水蚀而不是耕作侵蚀。还发现在这些倾斜的农田中，（137）Cs，SOC和总氮沿着相同的路径移动，从而在土壤重新分配期间导致净的C和N损失。应解决青藏高原坡地土地利用从草地转变为农田的负面影响。

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