土壤学报2017，Vol.54Issue(4)：874-884,11.DOI:10.11766/trxb201610130419
自然降雨条件下红壤坡面有机碳的选择性迁移
Soil Erosion-induced Selective Transfer of Organic Carbon in Red Soil Slope Field under Natural Rainfall
摘要
Abstract
[Objective] The red soil hilly region in South China is one of the areas of the country suffering serious soil erosion.Currently,the researches on loss of soil organic carbon with soil erosion in this region were executed mainly via simulated rainfall tests,without much in-situ field quantitative monitoring under natural rainfalls or comparison between fields different in land use.This study was intended to explore relationships of surface runoff and sediment loss with organic carbon carried in runoff and sediment under natural rainfall,so as to characterize responses of soil organic carbon transfer and loss to changes in rainfall,soil erosion and land use,and to deepen the scientific knowledge about relationship between soil erosion and carbon recycling.[Method] Tracts of bare land,grassland,citrus orchard,and secondary splash pine forest were selected for the experiment as runoff plots in the Jiangxi Soil and Water Conservation Ecological Science Park.Surface runoff,sediment loss and soil organic carbon carried therein were monitored under 24 typical rainfalls between March to August,2015 in order to illustrate selective transfer of soil organic carbon.[Result] Results show as follow:(1) Runoff coefficients and the soil erosion modulus increased with increasing rainfall intensity during all the 24 rainfall events.With the conversion of land use in type from bare land to orchard,grassland and forest,the effects of land use reducing runoff and sediment increased.Rainfall intensity was the major factor affecting runoff volume,while the latter was the one affecting sediment loss,with correlation coefficient being 0.89 ～ 0.92 (p ＜ 0.001) and 0.95 ～ 0.98 (p ＜ 0.05),respectively.(2) Under natural rainfalls,the concentration of organic carbon was 5.00,7.68,6.11 and 10.02 mg L-1 in runoff and 7.69,8.58,8.08 and 8.93 g kg-1 in sediment on the hare land,grassland,orchard and forest,respectively.The concentration of organic carbon in runoff was significantly and negatively related to volume of the runoff and so was the concentration in sediment with the volume of sediment loss.The sediment-associated loss of soil organic carbon in the four plots accounted for 64.67％,47.38％,53.94％ and 36.03％ of the total lost with the erosion,and reached 560.3 mg m-2,1.98 mg m 2 122.5 mg m 2 and 2.66 mg m-2 in intensity respectively.(3) The organic carbon enrichment ratio of the sediment in the bare land,orchard,grassland and forest was 1.27,1.10,0.80 and 0.58,respectively,and decreased gradually with increasing rainfall intensity.Selective transfer of organic carbon was more evident in weak rainfalls.[Conclusion] Under natural rainfalls,soil erosion has very important impacts on migration of soil organic carbon in slope fields in the red soil region.Selective migration of soil organic carbon with surface runoff or sediment is determined mainly by rainfall characteristics (especially rainfall intensity) and land use pattern.In all the lands,regardless of land use,intensified soil erosion makes it easier for soil organic carbon to migrate with sediment,and organic carbon enrichment ratio of the sediments also increases with intensifying soil erosion.However,organic carbon enrichment ratio of the sediment decreases with rising rainfall intensity.关键词
自然降雨/水力侵蚀/土壤有机碳/红壤坡面/富集比Key words
Natural rainfall/Water erosion/Soil organic carbon/Red soil slope/Enrichment ratio分类
农业科技引用本文复制引用
肖胜生,汤崇军,王凌云,段剑,杨洁..自然降雨条件下红壤坡面有机碳的选择性迁移[J].土壤学报,2017,54(4):874-884,11.基金项目
国家自然科学基金项目(41303064)、公益性行业(水利)科研专项(201501047)和江西省水利科技重大研究项目(KT201417)共同资助 Supported by the National Natural Science Foundation of China(No.41303064),the Special Fund for Water Resources Research in the Public Interest(No.2014BAD15B0303) and the Major Research Projects of Water Resources Department of Jiangxi Province(No.KT201417) （41303064）
