烟-稻复种连作对红壤性水稻土团聚体组成及稳定性的影响

Effects of Tobacco-Rice Continuous Cropping on Distribution and Stability of Soil Aggregates in Red Paddy Soil

红壤性水稻土面临土壤结构退化、土壤养分失衡和酸化等土壤质量问题,制约农业生产和农民增收。本文以南方红壤丘陵区植烟的红壤性水稻土为对象,采用时空替代法、相关及冗余分析等技术方法,研究了烟-稻复种连作(YDLZ)对红壤性水稻土团聚体及其稳定性变化的影响及其关键影响因素。YDLZ后的红壤性水稻土>5 mm团聚体含量、土壤团聚体重量平均直径(MWD)和几何平均直径(GMD)均显著降低,<0.25 mm团聚体含量和分形维数(D)则显著升高,土壤团聚体稳定性降低;且以YDLZ 5~10年(YDLZ5~10)对土壤团聚体粒径分布及稳定性影响最大。相关及冗余分析表明,土壤有机质和粘粒含量是引起团聚体分布的关键指标;>5 mm和<0.25 mm的团聚体含量是引起团聚体稳定性变化的关键指标。烟-稻复种连作引起红壤性水稻土有机质和粘粒含量变化,主要导致>5 mm团聚体含量的减少,<0.25 mm团聚体含量增加,从而土壤团聚体稳定性降低。针对YDLZ的红壤性水稻土结构培育和土壤质量保育,需关注土壤有机质及粘粒含量的变化。

Red paddy soil is facing quality problems such as soil structure degradation,soil nutrient imbalance and acidification,which have impeded the growth of agricultural production and farmers’income.In this paper,we sampled tobacco planting soil from the red soil hilly region in southern China,to explore the effects of tobacco-rice continuous cropping(YDLZ)on soil aggregates’distribution,aggregates’stability as well as the key influencing factors,based on the means of spatial-temporal substitution,correlation analysis and redundancy analysis.The results showed that the content of>5 mm soil aggregates,and the mean weight diameter(MWD)and geometric mean diameter(GMD)of soil aggregates decreased after YDLZ in red paddy soil,but the content of<0.25 mm soil aggregates and the aggregate fractal dimension(D)increased significantly;therefore,the stability of soil aggregates decreased.Meanwhile,the greatest influence was found on the distribution and stability of soil aggregates under the YDLZ years from 5 to 10(YDLZ5-10).Correlation and redundancy analysis(RDA)revealed that the contents of soil organic matter and clay were the key indexes that induced the variation of the soil aggregates distribution;and the content of>5 mm and<0.25 mm soil aggregates were the key indexes that caused the variation of the soil aggregates’stability.The change of organic matter and clay content in red paddy soil caused by continuous cropping of tobacco and rice mainly resulted in the decrease of>5 mm aggregates’content and the increase of<0.25 mm aggregates’content,which could reduce soil aggregate stability.Therefore,for the cultivation of soil structure and soil quality in red paddy soil of YDLZ,it is necessary to pay attention to the content variation of soil organic matter and clay.