Title: Influence of Feedlot Manure Applications on Soil Microbial Communities Associated with Short Grass Prairie and Conservation Reserve Program Grassland Authors
Submitted to: Microbial Ecology International Symposium
Publication Type: Abstract Only
Publication Acceptance Date: August 8, 2010
Publication Date: August 22, 2010
Citation: Rice, W.C., Todd, R.W. 2010. Influence of Feedlot Manure Applications on Soil Microbial Communities Associated with Short Grass Prairie and Conservation Reserve Program Grassland [abstract}. 13th International Symposium on Microbial Ecology. August 22-27, 2010, Seattle, Washington. 2010 Flashdrive. Technical Abstract: Available beef cattle manure exceeds the assimilative capacity of farm land in many areas of the High Plains. About half of the agricultural land base of the fed-cattle-producing region of the southern High Plains is grassland. This study documents the effect of annual (both fall and spring) applications of three rates of N (50, 125, and 200 kg/ha) in the form of feedyard cattle manure on grassland ecosystems and on soil microbial composition. Replicate treatments (n=4) of feedyard cattle manure N applications plus controls were made to native short grass prairie and old world bluestem grass ecosystems starting in the spring of 2000 and continued until the fall of 2006. A significant increase in biomass in response to N application was first observed in 2004 and continued through the last biomass sampling in 2007. Soil samples for microbial community composition at three depth ranges (0-2.5, 5.0-7.5, and 30.0 - 32.5 cm) were obtained in November of 2008. Microbial composition was investigated via DGGE-PCR methods using both general (V3 region) and improve-group specific 16S-PCR primers targeted at the following groups: Alpha-, Beta- and Gamma-Proteobacteria, Bacteriodetes, and Firmicutes. DNA sequence analysis of 16S rDNA gene libraries was also employed. DGGE-PCR data were analyzed by hierarchal clustering, group separation evaluation, and principal components analysis. Microbial community composition was most strongly influenced in order of importance by: 1) soil depth, 2) seasonal applications of manure over rate of N, and 3) by grassland composition. Manure applications also resulted in significant differences between 16S gene libraries as did soil depth. The influence of grassland type was subtle and complex. However, soil depth and manure application treatments provided a strong influence on overall microbial community composition and tended to obscure or suppress grassland influences on microbial community composition.