The Comparison Of Soil Humus Characteristics Of Paddy Soil With Different Reclamation Time

Soil is a synthesis of society?history and nature,it is also the basic of human society.Soil is in constant change and update with the combination of nature and man-made. Soil quality is an important standard to value the soil good or bad,it relates to the health of animal and human?the quality of environment and the sustainable development of the global biosphere.The study on soil is of great significance for all production and living.The studies of the paddy soil of the south China had a long history both at home and abroad.The history of northern paddy soil is short and they mostly transformed from the dry field, the studies about that are less.This paper is about the unclear problem of the impact on soil fertility and carbon fixation mechanism of the increasing northern paddy field reclamation area and the change of dry field to paddy field(referred to as "HanGaiShui")during a long time, the study is on paddy field of different cultivated fixed number of year(5 years, 30 years)of Guan Daodong village and the paddy field of different cultivated fixed number of year(5 years, 30 years,50 years)of Qing Shan village, the dry field of different cultivated fixed number of year(5 years, 30 years,50 years)of Qing Shan village are used for comparison. The main studies are about the changes of the total soil organic carbon and the composition of water soluble substance(WSS)?fulvic acid(FA)?humic acid(HA)?humin(Hu) and the HA structure characteristics of different cultivated fixed number of year paddy soil. To explore the changes of soil fertility characteristics of different cultivated fixed number of year paddy field through the studies. The results show:(1) The paddy soil with different reclamation time from the village of Guan Daodong,with the increase of cultivated fixed number of year: the available nutrients(readily available N, available P and readily available K) content increased; the soil organic carbon content and each component of humus content(WSS, FA, HA and Hu) increased; the PQ value increased, the humification degree deepened; the ?LgK value of WSS, FA and HA all decreased, the molecular structure became complicated; the H/C value decreased, O/C value increased of HA; the 2920/1720 value and 2920/1620 value decreased of HA, the molecular structure of HA became complicated.(2) The paddy soil with different reclamation time from the village of QingShan,with the increase of cultivated fixed number of year: the available nutrients content increased; the soil organic carbon content increased; the WSS, HA and Hu increased but the content of FA decreased; the PQ value increased, the humification degree deepened; the ?LgK value of WSS, FA and HA all decreased, the molecular structure became complicated; the H/C value decreased, O/C value increased of HA; the 2920/1720 value and 2920/1620 value decreased of HA, the molecular structure of HA became complicated.(3) The dry soil used for contrast which were from the village of QingShan, With the increase of cultivated fixed number of year: the available nutrient content decreased; the soil organic carbon content and each component of humus content decreased; the PQ value decreased, the soil humification degree reduced; the ?LgK value of WSS, FA and HA all increased, the molecular structure became simple; the H/C value increased, O/C value decreased of HA; the 2920/1720 value and 2920/1620 value increased of HA,the molecular structure of HA became simple.(4) The cultivated fixed number of 5 years,the soil organic carbon content?PQ value and the O/C value of HA of paddy soil from QingShan village lower but the H/C value of HA ?2920/1720 value and 2920/1620 value higher than the dry soil used for contrast;The cultivated fixed number of 20 years, the soil organic carbon content?PQ value? the H/C and O/C value of HA ?the 2920/1720 and 2920/1620 value of paddy soil from QingShan village are closed to the dry soil used for contrast;The cultivated fixed number of 50 years, the soil organic carbon content?PQ value and the O/C value of HA of paddy soil from QingShan village higher but the H/C value of HA ?2920/1720 value and 2920/1620 value lower than the dry soil used for contrast.There are no obvious clustering rules of the changes of component of humus content and ?LgK value.