Degree Type


Date of Award


Degree Name

Doctor of Philosophy



First Advisor

Randy Killorn


The possible effects of the application of swine manure and biosolids to high phosphorus (P) test soils has been widely debated due to the potential increase in P pollution. The application of these materials to soils might result in changes in water, soil, and crop quality. Increasing P in an already high soil P test (STP) soil may result in changing P dynamics in agro-ecosystems and enhancing P movement away from sorption sites. The purpose of this study was to determine the effect of swine manure (SM), biosolid (BS) and triple superphosphate (TSP) applications on the soil P content in a Webster soil. An incubation study and a field study were conducted where BS, SM and TSP were applied at three rates to a high STP soil. Soybeans and corn were planted in the field experiment. Soil, plant, and grain samples were analyzed for P and Mo. The application of BS, SM, and TSP to a high STP soil resulted in an increase of soil P. This increase of soil P resulted in different response to plant Mo accumulation. A high soil P did not cause an increase of either grain or whole plant Mo uptake in corn. However, increasing P application rate increased P and Mo concentration in soybean whole plant and grain. The results of this study suggest that the fate of P and Mo after 2 years of application of BS and SM is an accumulation in the soil plant system. Accumulations of P in already high STP soils may lead to potential movement of P off-site. This P movement out of sorption sites may contribute to the already high P surplus in the ecosystem. Accumulations of Mo in the soil and subsequently in soybean may increase the potential for molybdenosis in livestock that use soybean as main source of protein.



Digital Repository @ Iowa State University,

Copyright Owner

Jorge David Hernandez



Proquest ID


File Format


File Size

89 pages