David M. Burner

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

Effects of the Establishment of a Forested Riparian Buffer and Grazing on Soil Characteristics

Poultry-litter applications to pastures can result in relatively high soil phosphorus (P) levels, which in turn can contaminate runoff and degrade surface water quality. New management protocols for temperate grasslands are needed to reduce the risk of P transport to surface water. The effects of three land-use treatments on soil characteristics related to P runoff were investigated using small watersheds with 8% slope near Booneville, Arkansas, U.S. The land use treatments were (1) haying of bermudagrass overseeded with winter annual forage (ryegrass or rye), (2) rotationally grazed, and (3) rotationally grazed with 12-m-wide tree buffer on the downhill portion of the plot. Plots and trees were established in 2003. Annual spring application of poultry litter (5.6 Mg ha−1) to the hayed or grazed portions of the plots was started in 2004. Grazing treatments were imposed shortly thereafter. By the summer of 2008 (4 years of treatments), soil concentrations of Bray 1–extractable P and soluble reactive P had increased significantly from approximately 40 and 4 mg P kg−1 soil, respectively, to more than 200 and 30 mg P kg−1 soil, respectively, in the areas of the plots receiving poultry litter. Soil bulk density in the portions of the plots being grazed had increased significantly also. The soil collected from the forested riparian buffer in 2008 had similar soil bulk densities and Bray 1–extractable P concentrations as the plots did in 2003 before treatments were imposed.

Management factors affecting the establishment of pine based silvopastures in southern grasslands in the United States.

Silvopasture practices are being advocated as a means of maintaining pine forest acreage in the southeast United States; however, scientific data on the design and management for optimum tree growth are lacking. Studies were conducted near Booneville AR to determine the effects of weed control, irrigation, soil fertilization and protection from cattle grazing on the establishment of loblolly pines (Pinus taeda L.). Pine seedling growth during the first year after planting was increased significantly by weed control in a factorial experiment in which pre-plant fertilization, irrigation and weed control were treatments. In a follow-up experiment, first-year pine regeneration was increased by a high level of weed control. Pine seedling survival and growth up to 21 months after transplanting were significantly reduced when seedlings were planted into pastures grazed continuously by cattle. These results demonstrate the need for regulated graz- ing systems during pine regeneration and establishment of silvopastures and that pine growth is best when competing vegetation is minimal.

Ice Damage in a Chronosequence of Agroforestry Pine Plantations in Arkansas, USA

Abstract Acute (broken and leaning) and transient (bending) damage to loblolly pine (Pinus taedaL.) were assessed in a case study of experimental agroforestry plantations following a December 2000 ice storm. Stand ages were 7-, 9-, and 17-years-old and tree density ranged from 150 to 3,360 trees ha−1 in rectangular and multi-row configurations. Wider tree spacing or lower stand density of 7-year-old trees increased stem breakage, while closer spacing increased bending. There was substantial straightening of bent 7-year-old trees 8 months after the storm, and this recovery was determined more by degree of initial bend rather than height or diameter. Nine-year-old loblolly pine had 19% more top breakage and 59% more stem breakage than shortleaf pine (P. echinataMill.) (P < 0.001). Agroforestry design influenced ice damage in 7-year-old stands, but no design had catastrophic loss. Thinning from above caused an increased susceptibility of ice damage to a 17-year-old stand compared to a nonthinned stand. The case study supports the cultivation of loblolly pine in areas prone to ice damage.

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.