Degree Type


Date of Award


Degree Name

Master of Science


Agricultural and Biosystems Engineering


Agricultural and Biosystems Engineering

First Advisor

Adina Howe

Second Advisor

Cindy Cambardella


Addressing the growing demand for food from a burgeoning population requires agricultural methods that sustainably support increases in crop production while maintaining environmental health. Agricultural practices that include the use of compost, in lieu of mineral fertilizers, have been shown to reduce environmental impacts and improve soil health. Producers seeking to improve sustainability through compost use are challenged by the chemical form and availability of nutrients in organic amendments, limiting their ability to predict when nutrients will be available to crops. To better understand nutrient dynamics in soils amended with organic fertilizers, we compared the soil microbial community response to amendments with differing carbon and nitrogen content. Composted horse manure was chosen to represent an organic high carbon amendment, and alfalfa hay was chosen to represent a high nitrogen amendment. Amended soils were incubated for 97 days and destructively sampled on seven progressively longer incubation intervals. DNA was extracted for microbial community characterization, and measurements of nitrogen, carbon, and biomass were also compared for all samples. Our results showed significant shifts in soil microbial communities due to both time and amendment. Nutrient release was highly associated with amendment composition, with alfalfa showing the greatest release of plant available nutrients. We observed complex interactions between soils and amendments, with specific bacteria associated with nitrogen and carbon metabolism. These bacteria are targets for further characterization and better knowledge of their role in decomposition may contribute to the increased use of high organic matter fertilizer by producers and lead to a better understanding of sustainable crop production techniques.

Copyright Owner

Jared Scott Flater



File Format


File Size

45 pages