农田恢复措施对黑土母质发育的新成土壤团聚体微形态及孔隙结构的影响

Effect of farmland restoration practices on morphology and pore structure of soil aggregates newly developed from the parent material of Mollisol of China

土壤结构是土壤肥力的物质基础,水土流失等导致土壤结构退化成为威胁我国粮食安全的重要因素。本文利用8年田间定位试验,通过土壤切片技术,研究不同农田恢复措施(耕作和有机物料投入)对黑土母质发育的新成土壤团聚体微形态的影响,对理解成土过程和肥力快速恢复具有重要意义。结果表明:免耕土壤(自然、人工植被恢复)、不施肥耕作土壤和仅施化肥耕作土壤均为复合孔洞状微结构,主要孔隙形状均为面状或孔洞状,连通性及数量相当,土壤垒结和微结构类似;但土壤颗粒分布频度和均匀度及粗细粒质接触紧密度与耕作负相关,免耕土壤显著地高于耕作土壤(P<0.05)。施肥耕作土壤中,施有机物料的土壤为海绵状微结构,施高量有机物料的土壤微结构发育最好,施低量有机物料的土壤微结构次之,不施有机物料土壤微结构最差;其土壤垒结和微结构发育特征与有机物料的投入正相关。

Soil structure is the basic factor controlling soil fertility. Soil structure degradation resulting from loss of surface soil and extremly exposure of parent material due to soil and water erosion becomes an important threat to food security. The objectives of this study was to determine the effect of farmland restoration practices on morphology and pore strucgure of soil aggregates newly developed from the parent material of Mollisol of China using an 8-year field experiment,which was important to understand soil formation and fertility fast recovery. Results indicated that all of the no-tilled soils（ natural and anthropogenic vegetation restoration）,tilled soil without fertilization and tilled soil with mineral fertilization had composite hole shape microstructure,with similar shape（ face or hole shape） of predominant pores,equal connectivity and amount of pores,whose soil fabric and microstructure were similar; while no-tilled soils were dramatically higher than the tilled soils in frequency and homogeneity of soil particle distribution and closeness of coarse and fine material contact,with a negative correlation. Among the tilled soils,microstructure of soils with organic matter input were spongy; soils with high and full amount of organic material input developed best microstructure; the microstructure of soils with low and limited amount of organic matter input took the second place; the microstructure of soils without organic amendment were the worst. The characteristics of soil fabric and microstructure of tilled soils were positively related with organic material input.