Nutrient dynamic differences in former wetland soils following 80+ years of agriculture.
Borges, Ashlyn*,1, Johnson, Keith1, Bernacchi, Carl2, McConnaughay, Kelly1, Paul, Eldor3, Conant, Rich3, Morris, Sherri1, 1 Bradley University, Peoria, IL2 Illinois State Water Survey, Champaign, IL3 Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado
ABSTRACT- Soil C content and nutrient dynamics are important factors to developing plant communities and can be altered by moisture regimes. This study examines soil differences between two former wetlands that existed for 50 and 1,000+ years. Both former wetlands have been disturbed with soybean/corn cultivation for 80+ years, and are part of a large-scale restoration project along a major river system. Composite cores from 0-10, 10-25, and 25-50 cm depths were taken from the two former wetlands and an adjacent undisturbed wetland site. Soils were analyzed for bulk density, total and resistant carbon and nitrogen, and net nitrogen mineralization rates were determined using two 30-day incubations. Carbon and C/N did not differ between the two former wetland soils. However, nitrogen was marginally higher in the younger wetland. Resistant C, resistant N and the RC/RN ratio were higher in the younger wetland at 10-25 cm. Former wetland nutrient content was lower than the adjacent wetland. Nitrogen mineralization, nitrification and percent nitrification was significantly higher in the adjacent wetland soils following 30 days of incubation from 0-10 cm. After 60 days, adjacent wetland soils had significantly greater N mineralization and nitrification at 0-10 cm. However, the older former wetland had higher nitrogen mineralization and nitrification at 10-25 cm. These results suggest that nutrient content and nitrogen turnover currently differ between the former wetland sites and the adjacent wetland. We predict that restoration will result in changes in soil carbon dynamics and increased N turnover as sites are returned to wetlands.
Key words: soil nutrient dynamics, landscapes
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