耕作制度对紫色水稻土根际与非根际土壤有机碳矿化的影响

以稻田免耕长期定位试验点为平台,研究耕作制度对紫色水稻土根际与非根际土壤有机碳矿化的影响。结果表明,不同耕作制度下稻田土壤有机碳日均矿化量均表现前期快速下降而后逐渐趋于平稳,培养结束时有机碳日均矿化量仅为第1天的3.1%～6.7%;另外,实行稻油轮作可有效降低土壤有机碳矿化速率。垄作免耕(中稻-油菜)处理有机碳日均矿化量、累积矿化量及矿化强度均为根际大于非根际土壤,而其他处理则是根际小于非根际土壤。稻田根际与非根际土壤有机碳平均日均矿化量随培养时间均符合幂函数变化规律,在62d培养期内,除第1天外,非根际土壤平均日均矿化量均大于根际土壤平均日均矿化量,差异变幅范围为67.0%～98.7%。各处理稻田根际与非根际土壤有机碳日均矿化量、累积矿化量和矿化强度均与其相应pH显著相关;根际与非根际土壤间有机碳日均矿化量和累积矿化量差异均与其微生物生物量碳、氮含量显著相关。

Effect of Farming Systems on Soil Organic Carbon Mineralization of Rhizosphere and Non-rhizosphere in Purple Paddy Fields

Based on a 20-year-long fertilization experiment in paddy field,effects of farming systems on soil organic carbon(SOC) mineralization of rhizosphere and non-rhizosphere in paddy were studied.This experiment included four cultivation treatments: plain-cultivation(rice),ridge-cultivation without tillage(rice),ridge-cultivation without tillage(rice-rape) and plain-cultivation(rice-rape).The results showed that the daily mineralization of SOC declined rapidly in the first seven days and then gradually became more and more stable under different farming systems.At the end of incubation,the daily mineralization of SOC was only 3.1%～6.7% of the first day.Plus,the mineralization rates of SOC was decreased effectively when practiced the rotation of rice and rape.The daily and cumulative mineralization of SOC and mineralization intensity under the treatment of the rhizosphere of ridge-cultivation without tillage(rice-rape) were higher than those of non-rhizosphere,but other treatments were opposite.The daily mineralization of SOC of rhizosphere and non-rhizosphere fitted with a power-function with incubation time.The daily mineralization of SOC of non-rhizosphere was higher than rhizosphere in the whole incubation period of 62 days except the first day in all treatment.And discrepancy rate was between 67.0% and 98.7%.The daily and cumulative mineralization of SOC and mineralization intensity of rhizosphere and non-rhizosphere were significant correlation with pH.The discrepancy between rhizosphere and non-rhizosphere of daily and cumulative mineralization of SOC were evident correlation with microbial biomass carbon and nitrogen.