Long Term Tillage Effects On The Distribution Patterns Of Organic Carbon Within Soil Aggregates And Their Seasonal Change

The variation of soil organic carbon pool will affects the CO₂ concentration in atmospheric enormously and would have an important impact on global change.Farmland soil organic carbon pool is playing a pivotal role in soil organic carbon pool,so the research of variation of farmland soil organic carbon pool is very necessary.However,there are many complex factors affect the change of farmland soil organic carbon pool,including the climatic conditions,farm management practices, vegetation and soil physical and chemical properties,as well as changes in land use patterns and so on.We engaged this study in assumed that there are some factors remain unchanged,for the future provide the basis for further study.In addition,microbial biomass carbon and respiration measurement,can be more objective study of soil organic carbon pool changes.Following the results of research:1.Judging from the distribution of MBC in aggregate,under the three different kinds of tillage managements,MBC is enrichment in 2.0-0.25mm aggregate mainly;Judging from the tillage managements,the MBC contents in combining ridge with no-tillage conditions in aggregate are generally higher than conventional tillage and flooded paddy field,which some people with other similar conclusions;Judging from the seasonal change,as a result of this experiment in the sub-tropical monsoon climate zone,moderate temperature and precipitation in spring,more conducive to microbial growth,so in April in the MBC content of aggregates is usually the largest.2.Judging from the distribution of TOC in aggregate,TOC is enrichment in 2.0-0.25mm aggregate mainly;Judging from the tillage managements,under combining ridge with no-tillage, TOC content is often greater than the other two types of tillage managements;Judging from the seasonal change,the trend of TOC content vary is accord with trend of temperature changes in this study area.3.Judging from the distribution of DOC in aggregate,DOC is enrichment in 2.0-0.25mm aggregate mainly;In three different tillage managements,DOC content and no significant differences;Judging from the different seasons,DOC concentration increased with temperature increase.4.Judging from the distribution of POC in aggregate,POC is enrichment in 2.0-0.25mm aggregate mainly;Combining ridge with no-tillage significantly increase the POC content in the each size aggregate;Judging from the different seasons,the turnover of POC in the aggregate is generally a few years to several decades,so in one year there is no significant change in the basic.5.In three different tillage managements,soil respiration rate have the same distribution pattern,wasâ…¤-shaped distribution.Respiration rate in January of the smallest and the largest in July;Respiration rate of combining ridge with no-tillage soil was significantly lower than that of conventional tillage and flooded paddy field soil,a will protection of the soil organic carbon; Judging from the different seasons,respiration rate increased with temperature increase.