Daniel H. Pote

Growth and Soil Nutrient Responses to Stocking Rate and Nitrogen Source for Mid-Rotation Loblolly Pine in West-Central Arkansas

Fertilization is needed to replace nutrients removed from pine straw plantations, but tree response to fertilization could be influenced by stocking rate. Our objective was to determine effects of three N fertilizer sources on loblolly pine (Pinus taeda L.) growth and pine straw yield as a function of stocking rate (trees ha -1 , TPH) at about mid- rotation (12-14 years post-planting). Commercial mineral fertilizer (CF), poultry litter (PL, 5.4 Mg ha -1 ), and pelletized

Switchgrass Compositional Variations Arising from Spatial Distribution and Legume Intercropping

ABSTRACT Due to genetic diversity within and among switchgrass (Panicum virgatum), there may be genotype x environment and management-induced differences among secondary cell walls. Consequently, two separate experiments were conducted to determine feedstock variance using near-infrared spectrometry (NIRS). One experiment tested legume-intercrops [red clover (RC; Trifolium pratense), crimson clover (CC; Trifolium incarnatum), hairy vetch (HV; Vicia villosa), and partridge pea (PP; Chamaechrista fasciculata)], nitrogen (N) fertilization (0, 67, and 135 kg-N ha−1), and location impacts on characteristics. The second one determined on-farm bale variance within and across locations. Clustering NIRS data indicated that chemical signatures differed among locations and N-levels, but less so among intercrops. Results suggest that homogeneity may vary within a region responsible for supplying biomass to a biorefinery. Thus, conversion efficiencies and enzymatic requirements for ethanol production may be affected. Consequently, legumes may displace inorganic-N with minimal compositional changes, whereas location and N-level influence feedstock quality and recalcitrance level to a greater extent.

Short-Term Soil Responses for an Emulated Loblolly Pine Silvopasture

Pine (Pinus spp. L.) stands are often overstocked early in the tree rotation, prior to initial thinning. While pre- and/or post-thinning fertilizer applications are best-management practices to optimize growth of southern pines, there can be poor nitrogen (N) utilization and adverse environmental impacts associated with fertilization. Our objective was to determine short-term (3-year) soil responses of an emulated loblolly pine (P. taeda L.) silvopasture, which received a single application of commercial N–phosphorus (P)–potassium (K) fertilizer (CF) or pelletized poultry litter (PPL) applied at about midrotation (12 years postplanting). Compared to the control, CF decreased soil pH at depths of 0–10 and 10–30 cm, and PPL increased Mehlich 3 available P at 0–10 cm. Fertilizer responses were found for soil extractable ammonium (NH4 +)-N, and nitrate (NO3 −)-N concentrations, mineral N ha−1, pH, and available P but not for diel carbon dioxide–carbon (CO2-C) flux, total C, and total N. Total soil C, total soil N, pH, and available P decreased with depth, whereas mineral N ha−1 and 1 M potassium chloride (KCl)–extractable aluminum (Al) increased with depth. These results further our understanding of the nutrient dynamics during alley cropping of an upland soil and demonstrate the challenge in detecting short-term responses with fertilization.