Print PageSettlement of the Midwest, with the subsequent conversion of tallgrass prairie to agricultural fields, has led to a drastic reduction of carbon in the soil. As some agricultural fields are returned to grasslands, it is important to understand the factors influencing rates of carbon and nitrogen accrual in order to better predict carbon storage rate and capacity. The Conservation Reserve Program (CRP) encourages farmers to set aside previously cropped land to reduce runoff of sediment, fertilizer and herbicide as well as provide natural habitat. In this study we investigated the effect of soil and vegetation attributes on the rate of soil carbon and nitrogen accrual in remnant and restored tallgrass prairie and CRP lands in Newton County, Indiana and Lee County, Illinois in order to better predict soil carbon and nitrogen under differing levels of plant species diversity and soil texture. Soil samples were collected from depths up to 90cm from remnant and restored prairies, high and low-diversity farm conservation practices, and agricultural fields. Vegetation surveys and biomass collections were conducted in the prairie and conservation areas to estimate plant species richness, abundance, and productivity.
Results/Conclusions
As expected, aboveground biomass displayed a positive relationship with soil carbon and nitrogen, however, plant species richness showed a negative relationship with both soil carbon and soil nitrogen. The abundance of cool season grasses (C3) had a significant positive relationship with soil carbon and nitrogen, whereas the presence of other functional groups such as C4 grasses and legumes did not have a clear effect. Soil texture, measured as % silt + clay content, may be influencing patterns of plant species richness and productivity in our sampling area. Vegetation and soil texture can both affect soil carbon and nitrogen and should be accounted for when attempting to predict soil carbon storage in conserved or planted grasslands.
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