Inputs to the biosphere of chemically active compounds of nitrogen, known as reactive nitrogen, are increasing. These inputs have beneficial effects including increased crop production, and deleterious effects such as nutrient pollution. Forest soils can serve as sinks and sources for reactive nitrogen. The identification of mechanisms that allow forest soils to retain this nitrogen is an important research goal. This research will improve our understanding of reactive nitrogen retention by incorporating soil carbon and soil texture into an analysis of forest soil nitrogen retention. Soil carbon can promote the transformation of reactive nitrogen into non-reactive forms. In contrast, coarse soil texture can promote the transportation of reactive nitrogen to surface and ground waters. The relative importance of these processes will be evaluated along gradients of soil carbon and soil texture in a Chesapeake Bay watershed. The results will be integrated to determine how nitrogen transformation and transportation interact to control ecosystem losses of reactive nitrogen. An improved understanding of the mechanisms promoting nitrogen retention can help to determine when, where and why reactive nitrogen is transported to surface and ground waters. Soil texture offers a broadly applicable framework for interpreting these relationships.
Because soil texture is well-mapped across the globe, results from this research will enable managers to use existing soil texture maps to predict places and times where open waters are particularly susceptible to non-point nutrient pollution and to manage landscapes accordingly. An undergraduate student will participate in this project, and high school students will benefit from educational materials developed from this research.
