Submitted to: Biology and Fertility of Soils
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 3, 2005
Publication Date: December 20, 2005
Citation: Larkin, R.P., Honeycutt, C.W., Griffin, T.S. 2005. Effect of swine and dairy manure amendments on microbial communities in three soils as influenced by environmental conditions. Biology and Fertility of Soils. December 2005. 42: 1-11. Interpretive Summary: Effective application of manure amendments to croplands requires maximizing the recycling of nutrients to crops, while minimizing adverse environmental consequences. Understanding the impacts of manure amendments on soil microbial communities can provide valuable insight into nutrient availability and potential crop and environmental effects. Since soil microbiology is a critical determinant of these processes and is very sensitive to changes in soil conditions, effects on soil microbial communities can indicate important effects on nutrient cycling and availability. In this study, soil type was observed to have the greatest effect on soil microbial community characteristics, causing differing effects of manure amendments based on soil type. Overall, dairy and swine manure amendments were found to increase microbial populations, activity, diversity, and certain microbial subgroups in all soils. Dairy manure had greater effects than swine manure on several specific characteristics due to greater C inputs. Temperature and moisture regime had relatively minor effects on soil microbial communities. These results indicate the importance of soil type and other environmental factors that need to be considered when evaluating manure effects. This information is most useful to scientists for monitoring, evaluating, and predicting effects of organic amendments on soil processes and nutrient management.
Technical Abstract: Understanding the impacts of manure amendments on soil microbial communities can provide valuable insight into nutrient availability and potential crop and environmental effects. Soil microbial community characteristics, including microbial populations and activity, substrate utilization (SU) profiles, and fatty acid methyl ester (FAME) profiles, were compared in three soils amended or not amended with dairy or swine manure at two temperatures (18 and 25 C) and two soil water regimes (constant and fluctuating) in laboratory incubation assays. Soil type was the dominant factor determining microbial community characteristics, resulting in distinct differences among all three soil types and some differing effects of manure amendments at different temperatures and water regimes. Both dairy and swine manure generally increased bacterial populations, substrate diversity, and FAME biomarkers for gram negative organisms in all soils, temperatures, and water regimes. Microbial activity was increased by both manures in an Illinois soil, but only by dairy manure in the two Maine soils. Dairy manure had greater effects than swine manure on substrate utilization and FAME parameters such as increased activity, utilization of carbohydrates and amino acids, substrate richness and diversity, and fungal FAME biomarkers. Overall, microbial characteristics were more highly correlated with soil physical factors and soil and amendment C content than with N levels. These results indicate the importance of soil and environmental factors on microbial communities, and need to be considered when evaluating manure amendments.