Microbial Community Diversity in Alleys and Tree Rows in a 20 Year Alley Cropping System in North Eastern Missouri.

Soil physical and chemical properties in the cropped areas and tree rows in alley cropping configuration varies greatly due to differences in litter quality and microclimate in areas under trees compared to those in the alleys. Soil properties greatly impact microbial diversity and function and thus in alley cropping systems, the microbial composition and diversity could be different between soils in tree rows and cropped areas. The objective of this study was to compare and contrast the soil microbial diversity and composition in the cropped areas and tree rows in a 21 year old alley cropping system. Soils samples were taken in three parallel transects to a depth of 10 cm in the tree row and at the middle of the alley in a silver maple (Acer saccharinum) alley cropping system with a companion maize (Zea mays) – soybean (Glycine max) rotation. Soil bulk density, %C, and %N were similar between the different transects while minor differences were observed between cropped areas and tree rows. No significant difference in microbial diversity was observed between the tree rows and cropped soil based on soil DGGE profiles, band richness (19.6 and 22.8) and Shannon-Weiner diversity (2.958 and 3.099) respectively. Identification of bacterial genera revealed dominance of gram +ve as well as gram –ve bacteria in both soil types. Ordination plot revealed no clustering effect based on location (transect) or on the cropping system in the different samples. Microbial diversity in cropped areas most likely were influenced by the expanding tree roots as well.