Dynamics Of Organic Carbon And Its Typical Influence Factors In Greenhouse Vegetable Soils From Wuhan Suburbs

Greenhouse vegetable industry plays an important role in solving the problem of the supply of seasonal vegetables, ease the contradiction between more people and less land, and improving the income of inhabitant, emerging as the times require. Because greenhouse soil has the special environment conditions of “ high temperature ? high humidity?frequent continuous cropping?continuous vast fertilizing?no rain washing”and so on, the soil physicochemical must differ from vegetable field under natural environment conditions. Because of playing an important role in the global carbon cycle, organic carbon in soil have a direct impact on carbon balance in the accumulation and decomposition of global change directly. In the research, we use the greenhouse soils as the research object to study on the content and form of organic carbon in greenhouse soils and investigate influence of several typical factors on variety of organic carbon by combining analysis of field sampling with the indoor simulation experiment. We mainly draw the following conclusions:(1) TOC?DOC?MBC and ROOC in greenhouse soils were higher than the open field soils. During the planting period of 1~5 years, the contents of TOC?DOC and MBC were stable, and increased with the increase of planting time during the planting period of 5~20 years.(2) The contents of TOC were 6.1% higher in the rotation mode of “water spinachgarlic” than the rotation mode of “water spinach- celery”, and the contents of MBC in different seasons were 13.5%?9.2% and 37.2% higher respectively. The contents of DOC and ROOC were stable in different rotation mode.(3) Compared to the open field soils of corresponding layer, the contents of TOC were not changed obviously at the depth of 40 cm in greenhouse soils, and the contents of MBC were not changed obviously at the depth of 60 cm in greenhouse soils. The DOC and ROOC showed obvious phenomenon of surface accumulation and vertical migration and their contents were higher than surface soil at the depth of 100 cm(4) During temperature from 4? to 25?, the contents of ROOC and MBC were raised and DOC reduced by the with increasing of temperature. During p H from 5.30 to 8.34, the lower the p H was, the more the contents of ROOC and MBC reduced and DOC increased.(5) The contents of DOC?MBC and ROOC became lower in the condition of high saline soil. In greenhouse soils,the organic carbon mineralization rate decreased and the ratio of HA/FA in humus raised in the condition of higher temperature?closing to 7 of soil p H or higher soil Stalinization.(6) During 5 factors of carbon species?phosphorus species?temperature?moisture and p H in the soil, temperature?carbon species and their interaction influenced the degree of variation of organic carbon. In the indoor simulation experiment for 30 days, the influences of various factors on the variation of organic carbon were not significant.