Master of Science, University of Toledo, 2018, Biology (Ecology)

A principle driver of water-polluting harmful algal blooms (HABs) in agricultural watersheds is fertilizer phosphorus (P) runoff from farm fields. Because P is essential to plant growth, eliminating P application is infeasible. However, much of the P that is added to soils as fertilizer binds tightly to soil particles and is relatively unavailable to plants. In natural systems, microbial and faunal decomposers can increase soil P availability to plants. In agricultural systems, stimulating these organisms may help maintain P availability with decreased P application rates, thereby increasing P application efficiency while reducing runoff potential. We tested the hypothesis that stimulating soil fauna with sodium (Na+) and microbes with carbon (C) would increase soil P availability to plants. We added corn stover and Na+ solution to plots in conventionally-managed corn fields in Northwest Ohio. Stover treatments increased microbial biomass and activity and Na+ and stover combined increased soil faunal activity. However, even in both control plots and plots with stimulation of soil microbes and fauna, soil biological activity was low, and was not correlated with P availability. Therefore, in fields with low levels of decomposer activity, organisms may play a limited role in soil P cycling. In these types of ecosystems, treatments to stimulate decomposers already in those systems may be ineffective in reducing P runoff potential, at least in the short term.

Committee: Michael Weintraub PhD (Committee Chair); Daryl Moorhead PhD (Committee Member); Shannon Pelini PhD (Committee Member) Subjects: Agriculture; Ecology; Environmental Science