Thursday, 10 November 2005 - 9:15 AM
324-5

Carbon and Nitrogen Status of Forest and Pasture Soils Nine Months after Poultry Litter Application.

Robert L. Ficklin1, Joshua Richardson2, and Hal O. Liechty2. (1) University of Arkansas- Monticello, AFRC, 203 Forest Resources Bldg., Monticello, AR 71656, (2) University of Arkansas at Monticello, School of Forest Resources, Monticello, AR 71655

The use of poultry litter as a fertilizer in agronomic systems results in positive crop growth responses, but information on the influence of litter applications in silvicultural settings is limited. Furthermore, the effect of litter on carbon (C) and nitrogen (N) dynamics in pasture and forest settings is not well documented. In this study changes in soil C and N one growing season after poultry litter applications to pasture and pine plantation soils were measured. Six paired plots- control and treatment pairs- were established on similar soils, and treatment plots received 9 Mg/ha of poultry litter with concentrations of 251.1 g/kg and 35.9 g/kg of C and N, respectively. Antecedent C and N contents to a 15cm depth were higher for pasture than forest soils; however, no differences were observed at the 15-30cm depth between the two land uses. After litter application, pasture N contents remained higher in the surface 15cm, but the C content did not differ following treatment. No change was observed for C or N in the 15-30cm depth following treatment. Potential N mineralization was estimated for the surface 15cm of forest and pasture soils following a 28 day aerobic incubation. Organic N concentrations were higher in pasture soils than forest soils; however, more organic N was mineralized in the forest soils than the pasture soils. Mineralization of N decreased in both forest and pasture soils compared to control areas after treatment. C:N ratios were 12:1 or lower across all study plots, and we hypothesize that the decrease in mineralization was due to limited availability of C. The long-term influence of litter applications on the quantity and forms of N in forest soils compared to pasture soils remains unclear, so additional sampling is required to track changes in C and N dynamics after multiple poultry litter applications.

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