|Sauer, Thomas - Tom|
Submitted to: North American Agroforestry Conference
Publication Type: Abstract Only
Publication Acceptance Date: 6/25/2003
Publication Date: 7/24/2003
Citation: Sauer, T.J., Brahana, J.V., Skinner, J.V., Defauw, S.L., Hays, P.D., Coblentz, W.K., Moffitt, D.C., Robinson, J.L., James, T.A., Hickie, K.A. 2003. Nutrient assimilation by a silvopastoral system receiving annual applications of poultry litter [CD-ROM]. North American Agroforestry Conference. Columbia, Missouri.
Technical Abstract: Increasing intensity of confined animal feeding operations (CAFOs) can create serious challenges for implementing environmentally acceptable manure management practices. The objective of this research was to quantify various components of nutrient (N and P) cycling in a silvopastoral system receiving annual poultry litter applications. Four rows each of northern red oak (Quercus rubra), eastern black walnut (Juglans nigra) and pecan (Carya illinoensis) were planted at 15 m row spacings on a 4.25 ha site near Fayetteville, AR in 1999-2000. Alleys between tree rows were seeded to orchard grass (Dactylis glomerata var. Benchmark) in the fall of 2000. Beginning in 2001, ½ of the site received a single 4.5 Mg/ha poultry litter application each spring, which resulted in an application of approximately 110 kg of N and 40 kg of P per ha. The remaining area of the paddock received 56 kg/ha N as commercial fertilizer each spring and fall. Soil water samplers (0.6 and 1.2 m depths) and shallow ground water monitoring wells (0.4 - 5.5 m) were installed in both litter-treated and untreated areas in 2000-2001. Annual soil sampling (0-0.15 m) for total N and C, P, K, pH, EC, and micronutrients was begun in 2000. Monitoring results for the 2002 growing season indicate consistently greater concentrations of NO3-N in both soil water and ground water samples collected from the area receiving commercial fertilizer. Average NO3-N concentrations for the soil water samples were 6.7 and 4.0 mg/L for the untreated and litter-treated areas. Ground water samples displayed the same trends, as average NO3-N concentrations in ground water samples were 4.5 and 3.4 mg/L for the untreated and litter-treated areas. Very little change in soil P concentrations were observed as both litter-treated and untreated areas averaged ~35 mg/kg P as measured by the Mehlich 3 extract. However, P concentration in forage harvested from the litter-treated area had consistently greater (~0.05%) total P. Tree, forage, and environmental monitoring will continue and intensify as the trees mature to identify and quantify the major pathways of nutrient and C cycling in this system.