The Study Of Soil Organic Carbon Decomposition Under The Incubated Condition At Laboratory In Subtropical And Temperate Zones

In carbon cycling, the terrestrial soil carbon cycling is closely linked with therelationship of human being. Reserve of soil carbon pools is decided soil organic carbonaccumulation and decomposition rate. A little change of soil organic carbon may lead tomore change of carbon dioxide. The paper tries to research the decomposition of soilorganic carbon under different soil types in the subtropical and temperate zones, educes thecurves of soil organic carbon decomposition rate, curve-fit using statistic software, andanalyzes parameters in order to find the rule. Meanwhile, the paper also researches thefactors of soil organic carbon decomposition.Soil samples are obtained from Liping located in Guizhou province, Yujiang in Jiangxiprovince, Nanjing in Jiangsu province, Changbaishan in Jilin province, Qilianshan inGansu province and Ejina banner in Inner Mongolia. There are sixty-six treatmentsaccording to different soil types, vegetations, land-use and altitudes. Soil dried and sievedis incubated for 100 days.The results show: there is a faster decomposition rate in the beginning incubation period,and a slower in the late. The maximum rate of decomposition of soil organic carbon insubtropical wetness area is red soil under coniferous and broad-leaved mixed forest＞yellowsoil under grass＞yellow soil under shrub＞yellow soil under broad-leaved forest＞red soilunder camellia oleifera; decomposition rate of yellow soil is faster than red soil. Themaximum rate of decomposition of soil organic carbon in subtropical wetness zone isyellow-brown soil under mixed forest in Nanjing＞red soil under adult fir in Yujiang＞redsoil under broad-leaved forest in Yujiang. In the subtropical cropland soil, decompositionrate of organic carbon in paddy soil due to ground water is periodical water-logginghuangnitian＞gley huangnitian＞submerged huangnitian; decomposition rate of organiccarbon in dry land soil is vegetable soil in Nanjing＞red soil in Yujiang＞fluvo-aquic soilinYujiang. Effect of water content on decomposition of soil organic carbon in vegetable soilis low-water content is not beneficial to soil organic carbon decomposition of paddy soiland vegetable garden soil, medium-water content is good for decomposing soil organiccarbon of vegetable garden soil, high-water content benefits the one of paddy soil.Decomposition rate of organic carbon in temperate wetness zone is brown coniferous forestsoil＞dark-brown soil, mature spruce grey cinnamon forest soil＞original spruce greycinnamon forest soil＞original fir grey cinnamon forest soil, sub-high mountainous meadowsoil＞mountain meadow soil＞high mountainous meadow soil. Decomposition rate oforganic carbon in temperate dry area is elder populus euphratica fengsha soil＞youngerpopulus euphratica fengsha soil＞salix fengsha soil＞eldest populus euphratica fengsha soil.Compared curve of soil organic carbon decomposition rate of different soil types, theresult shows: decomposition rate of organic carbon in temperate forest zone is brownconiferous forest soil＞dark-brown soil＞meadow soil＞grey cinnamon forest soil＞fengsha soil; decomposition rate of organic carbon in subtropical forest zone is yellow soil＞yellowbrown soil＞red soil; decomposition rate of organic carbon in subtropical cropland area isvegetable soil＞paddy soil＞red soil＞fluvo-aquic soil. Compared carbon pools and turnovertime under different soil types, the result shows: soil total organic carbon is grey cinnamonforest soil＞dark-brown soil＞meadow soil＞brown coniferous forest soil＞red soil＞yellowsoil＞yellow brown soil＞paddy soil＞red soil (vegetable)＞flubo-aquic soil＞fengsha soil,temperate forest soil＞subtropical forest soil＞subtropical cropland soil＞temperate dry soil.Active carbon is temperate forest soil＞subtropical soil. Ca/SOC% of fengsha soil is most.The turnover time of active carbon in subtropical cropland soil is least, slow carbon is thattemperate forest soil is most, fengsha soil is least. Cr/SOC% of brown coniferous forest soilis most.Power function is used to curve-fit of organic carbon cumulation losing capacity. Thereis a better correlation. It is applicable in these areas.The result is b₁ on cropland soil＜b₁ onforest soil in temperate zone; as a whole, b₁ on forest soil in subtropical zone＞b₁ on forestsoil in temperate. B₀ is Changbaishan＞Qilianshan＞Liping＞Yujiang forest＞Yujiangcropland＞Ejinaqi.The curve-fits of soil organic carbon in other climate zones all of the country areadded. The general function is made by this way, which benefits the research on soilorganic carbon decomposition and to find the law of soil organic carbon decomposition. Itis basic of soil organic carbon decomposition theory.