Research On Carbon Sequestration In Two Kinds Of Parent Materials Of Chernozem

The study on the performance and potential of carbon sequestration in chernozem,plays an important role in carbon sequestration mechanism,which reveals the rich chernozem soil fertility improvement theory and provides a theoretical basis for the formulation of the soil environment-friendly fertilization.This paper takes Jilin Province loess and red soil area and the development of different organic matter content of chernozem soil as tested soil.Through the laboratory straw cultivation experiment and the adsorption experiment,the study of the adsorption and fixation of straw-transformed carbon and humus carbon from chernozem top soils and parent materials were focused.At the same time,the effects of adding corn straw on soil aggregate composition and organic carbon distribution in top soils and parent materials.The main conclusions are as follows:The change of the clay content in the top soil of the loess parent material particle composition was between 18.90% and 35.26%,with an average value of 25.29%.The soil texture was mainly sandy clay loam.The change of clay content in the top soil of laterite parent material particle composition was between 10.41% and 16.68%,with an average value of 13.06%.The soil texture was not only sandy clay loam,but also sandy loam and loamy sand.The average contents of DCB soluble components(free iron and aluminum oxide)in the top soils of loess parent material and laterite parent material were 12.22 g·kg-1 and 13.09 g·kg-1,respectively.The mineral composition mainly included 2:1 layer crystal structure vermiculite,montmorillonite,Illite,also contained a small amount of 1:1 kaolinite and other clay minerals and a small amount of quartz,the top soil developed in the laterite parent material also contained feldspar.The average cation exchange capacity(CEC)in the top soils of loess parent material and laterite parent material were 19.93 cmol·kg-1 and 14.49 cmol·kg-1,respectively.The soil clay content of loess parent material and laterite soil parent material were 28.79% and 27.98% respectively,with an average value of 28.39%.The soil texture was sandy clay.The CEC of loess parent material and laterite parent material were 23.43 cmol·kg-1 and 27.61 cmol·kg-1,DCB soluble components were 17.63 g·kg-1,28.13 g·kg-1,respectively.The above composition and physical-chemical properties of chernozem organic carbon fixation laid a rich material basis.The total organic carbon,heavy fraction organic matter,heavy fraction organic matter increment and compound quantity were increased with the increase of the straw addition,but the compound degree showed a gradually decreasing trend after adding the corn straw.Compared with the top soils,the increment of heavy fraction organic matter in the parent materials were higher than them,and the laterite parent material was slightly larger than loess parent material.With the increase of organic carbon content in the original soil,the increasing increment of heavy fraction organic matter and compound quantity were gradually decreasing.The consequence showed that the soil with low organic carbon had higher carbon sequestration potential,the carbon sequestration potential of two parent materials are much greater than top soils,and laterite parent material was stronger.The content of aggregates with different straw addition were increased with the decrease of aggregate size(>0.25 mm),and then decreased(<0.25 mm).For top soils,the greater the content of the organic carbon,the more >0.25 mm aggregates.The maximum content was 1~0.25 mm aggregates.For two parent materials,the maximum content was 1~0.25 mm aggregates of loess parent material,the maximum content was 2~1 mm aggregates of laterite parent material.>2 mm aggregates and >0.25 mm aggregates content increased with the increase of the straw addition.The higher the content of soil organic carbon,the more the two aggregates.The content of <0.25 mm aggregates decreased with the increasing of the straw addition.The decline of the two particle size of micro aggregates is roughly the same.The <0.25 mm aggregates content of laterite parent material is less than the loess parent material.There is a significantly increasing tendency of soil aggregates organic carbon content increased after the straw addition.For microaggregates(>0.25 mm),the organic carbon mainly distributed in >2 mm aggregates.The growth rate of organic carbon in two parent material aggregates was greater than the top soils.For microaggregates,organic carbon mainly distributed in <0.106 mm aggregates.The <0.106 mm aggregates organic carbon content was the highest under any amount of straw.The higher the content of top soil organic carbon,the higher the organic carbon content of each aggregate.For the two kinds of soil parent materials development of chernozem,the kinds of parent material have no significant effect on aggregate organic carbon content.The test samples on the adsorption kinetics of chernozem humic acid 2 h can reach the adsorption equilibrium,adsorption kinetics were consistent with Elovich equation.Two kinds of soil parent materials are in line with the Langmuir equation on chernozem adsorption isotherm of humic acid.By the Langmuir equation,it can be seen that the maximum soil adsorption capacity of the top soil of laterite parent material is higher than that of the top soil of loess parent material.For the two top soils,the average adsorption capacity of the original soil,clay and silt was 26.272 mg·g-1,57.481 mg·g-1,38.13 mg·g-1,respectively.Compared with them,for the loess parent material,the average adsorption capacity of the original soil,clay and silt was 52.458 mg·g-1?68.945 mg·g-1?58.360 mg·g-1,respectively;for the laterite parent material,the average adsorption capacity of the original soil,clay and silt was 58.058 mg·g-1?74.482 mg·g-1?63.139 mg·g-1,respectively.The maximum adsorption capacity of the parent material is larger than that of the top soils,and the laterite parent material is larger than that of the loess parent material.When the carbon source is sufficient,although the original soil organic carbon content of two parent materials is very low,its carbon sequestration potential is greater than the top soils.