不同稻蟹模式对土壤团聚体腐殖质特征的影响

Effects of Different Rice^crab Production Modes on Soil Humus Characteristics in Different Aggregates

采取田间定位试验与室内分析的方法,研究了有机稻蟹、常规稻蟹和单作水稻3种模式对土壤团聚体组成、各级团聚体中有机碳的分布、团聚体中腐殖质组成和胡敏酸光学性质的影响。结果表明:不同模式下团聚体含量均随粒级的减小表现为先升高后降低的趋势,2~0.25mm为优势粒级团聚体,所占比例高达46.73%~51.56%;与常规稻蟹模式和单作水稻模式相比,有机稻蟹模式可明显提高各级团聚体内有机碳以及胡敏酸碳(HAC)和富里酸碳(FAC)的含量。有机稻蟹模式各级团聚体中有机碳含量较单作水稻模式分别提高59.40%、64.44%、23.46%和15.88%;与单作水稻模式相比,有机稻蟹模式2~0.25mm和<0.053mm粒级团聚体中HAC含量明显增加,增幅分别为31.10%和30.82%;有机稻蟹模式和常规稻蟹模式2~0.25mm和<0.053mm粒级团聚体中FAC含量较单作水稻模式均显著提高,分别为56.26%、17.80%和27.58%、22.47%;有机稻蟹模式各级团聚体中胡敏酸(HA)的Δlog K值最高,标志着HA分子向新成化方向发展。因此,有机稻蟹模式不仅可以增加各级团聚体中有机碳的数量,而且能够改善土壤腐殖质品质,提高土壤肥力。

By using the field location test and laboratory analysis,the soil samples were analyzed for the composition of aggregates,distribution of organic carbon,the composition of humus and optical property of humic acid（HA） in four aggregates under the organic rice ~crab,the conventional rice ~crab and the rice monoculture mode.The results showed that the aggregate contents firstly increased and then decreased with the decrease of aggregate size.2-0.25 mm aggregate was dominant,with the proportion up to 46.73%-51.56%;the organic rice ~crab could significantly increase the contents of total carbon,humic acid carbon（HAC） and fulvic acid carbon（FAC） in four aggregates.Compared to the conventional rice^crab and rice monoculture mode,organic carbon content in the organic rice^crab mode increased by 59.40%,64.44%,23.46% and 15.88%.Compared to the rice monoculture mode,in the organic rice ~crab mode the HAC contents of 2-0.25 mm and 0.053 mm aggregates significantly increased by 31.10% and 30.82% respectively.The FAC contents of 2-0.25 mm and 0.053 mm aggregates in the organic rice ~crab and the conventional rice ~crab mode both significantly increased when compared with the rice monoculture mode,by 56.26%,17.80% and 27.58%,22.47% respectively.Organic rice^crab mode had the highest Δ log K ratio of humic acid（HA） when compared with the conventional rice^crab and rice monoculture mode.It suggesfed that humic acid（HA） molecule developed to younger direction.Consequently,the organic rice ~crab mode was more effective in raising the quantity of soil organic carbon,increasing the content of HAC and FAC in four aggregates than other modes.Under organic rice ~crab mode,much younger and simpler HA molecule caused the soil to be more active,improved soil quality and fertility.