Effects Of Calcium On Organic Carbon Distribution In Cultivated Brown Soil Aggregates

Soil carbon library in terrestrial ecosystems is one of the largest and most active organic carbon,and soil aggregate is the important place to maintain soil organic carbon,is very important to soil carbon and soil fertility.Calcium is one of the medium nutrient elements necessary for plant growth and development and is an important regulator of many physiological and biochemical processes.Meanwhile,calcium is also a good cementing agent,which plays an important cementing role in the formation of soil aggregates.Therefore,it is of great significance to study the effect of calcium on the distribution of organic carbon in soil aggregates on the carbon sequestration of cultivated land.Based on cultivated brown soil as the research object,research under the condition of different fertilization in the accumulation of organic carbon in soil calcium and aggregate correlation,on the basis of the indoor temperature simulation training,the use of stable isotopes of the delta ¹³C calibration corn stover,exogenous calcium on soil organic carbon was studied on the influence of cultivated land in brown soil aggregate distribution.The main research results are as follows:?1?The application of organic fertilizer increases the content of 1?2 mm granulocular aggregates in the soil and the degree of soil agglomeration.However,the application of nitrogen fertilizer reduced the content of 1?2 mm granular aggregates and increased the content of0.053?0.25 mm granular aggregates,but the difference with CK was not significant?P<0.05?.?2?Application of organic fertilizer increased the total calcium content of 1?2 mm and0.25?1 mm granule aggregates,and the application of nitrogen fertilizer reduced granule aggregates.Compared with CK,single application and application of organic fertilizer and nitrogen fertilizer increased the content of water-soluble calcium.However,organic fertilizer increased the exchange of calcium and acid soluble calcium in soil and at all levels,and the trend of nitrogenous fertilizer was reversed.?3?The content of total and active organic carbon in soil was increased by the application of organic and nitrogen fertilizers.Organic fertilizers increased the total organic carbon content of 0.053?0.25 mm grain size aggregates and the active organic carbon content of 0.053?0.25mm and<0.053 mm grain size aggregates.Nitrogen fertilizer increased the total organic carbon and active organic carbon content of 0.25?1 mm and 0.053?0.25 mm grain size agglomerates.?4?Under the condition of applying organic fertilizer,except for 1?2 mm grain size,the acid-soluble calcium of aggregates of all grain sizes was positively correlated with the total organic carbon and the content of active organic carbon.Except for the grain size<0.053 mm,the content of water-soluble calcium and total organic carbon in the aggregates of the whole soil and other grains were significantly positive.Under the condition of nitrogen fertilizer application,water-soluble calcium and total organic carbon content were significantly positively correlated in the whole soil and granular aggregates of 0.25?1 mm and 0.053?0.25mm.The contents of acid-soluble calcium and total organic carbon in agglomerates of different grain sizes were significantly negative.In addition to 0.053?0.25 mm grain size,there was a significant negative correlation between acid-soluble calcium and active organic carbon content in the whole soil and the other three granule size aggregates.In general,the correlation between acid-soluble calcium and water-soluble calcium and organic carbon in soil and agglomerates at all levels is relatively high.?5?The content of 1?2 mm granulocular aggregates in soil treated with single application and combination of exogenous calcium and maize straw increased with the culture time.Compared with CK,the increase rate was Ca1>Ca2>J>Ca1J>Ca2J.The content of exogenous calcium and maize straw 0.25?1 mm granulocular aggregates decreased with the culture time.Compared with CK,the increase rate was Ca2J>Ca1J>J>Ca2>Ca1.The grain size of0.053?0.25 mm and<0.053 mm in each treatment increased with the increase of culture time.?6?Single application of exogenous calcium increases the total organic carbon content of soil and aggregates at all levels.The application of exogenous calcium fertilizer also increased the content of active organic carbon in the whole soil and the aggregates of 0.25?1 mm and<0.053 mm grain size.Compared with single application of maize straw,exogenous calcium increased the total organic carbon content of 1?2 mm and 0.25?1 mm granule and activated organic carbon content of the whole soil.Exogenous calcium increased the content of soil new carbon in 1?2 mm and 0.25?1 mm granular aggregates,but decreased with the increase of culture time.Among them,the content of new carbon was relatively high in 0.053?0.25 mm granular aggregates.The content of new carbon decreased with the increase of exogenous calcium application.