Tree Nutrition and Forest Fertilization of Pine Plantations in the Southern United States

Abstract

The growth of many pine plantations in the southern United States is limited by soil nutrient availability. Therefore, forest fertilization is a common silvicultural practice throughout the South. Approximately 1.2 million ac of pine plantations were fertilized in 2004. In the last 10 years, considerable advances have been made in identifying the ecophysiological basis for stand growth and the response to fertilizer additions. Nitrogen (N) and phosphorus (P) are the nutrients that most commonly limit growth of southern pine. On wet clay soils in the lower Coastal Plain and on some well-drained soil in the upper Coastal Plain, severe P deficiencies exist. On these soils, P fertilization with 25–50 lb of P per acre at the time of planting produces a large and sustained growth response, on the order of 50 ft3 ac−1 yr−1 (1.5 tn ac−1 yr−1) throughout the rotation. On most other soils in the South, chronic deficiencies of both N and P exist. On these sites, soil nutrient availability often is adequate early in the rotation when tree demand is small. However, around the time of crown closure, N and P frequently become limiting. Fertilization with both N and P in these intermediate aged stands typically increases growth for 8–10 years. The growth response to a combination of 25 lb of P per acre plus 200 lb of N per acre averages around 55 ft3 ac−1 yr−1 (1.6 tn ac−1 yr−1) for an 8-year period. The amount of leaf area in the stand is the main factor determining the current growth rate of the stand and the potential growth response after fertilization. When stand leaf area index is less than 3.5, light capture by the stand is restricted and growth is negatively affected. In many of these stands, fertilization will increase leaf area because of increased soil nutrient availability and thus increase growth. The financial return after fertilization depends on the growth response that occurs, the cost of the fertilizer treatment, and the stumpage value of the timber produced. Using a growth response of 55 ft3 ac−1 yr−1 over 8 years, a fertilizer cost of $90 ac−1, and stumpage values from the first quarter of 2006, the internal rate of return from midrotation fertilization of a loblolly pine plantation with N and P would be approximately 16%.

Carbon payback period and carbon offset parity point of wood pellet production in the South‐easternUnited States

“…Both the ownership class and forest management type are indications of timberland ownership objectives, for example, planting is seen as an upfront investment for commercial wood production (Butler & Wear, ). In the Southern United States, Best Management Practices (BMP's) were developed to minimize the environmental impact of intensive harvesting and site preparation, for example, soil erosion and offsite movement of sediment (Fox et al ., ). For example, in Georgia the latest version of the Georgian BMP was developed to ‘establish sound, responsible, guiding principles for silviculture operations’ (GFC, ).…”

“…For example, in Georgia the latest version of the Georgian BMP was developed to ‘establish sound, responsible, guiding principles for silviculture operations’ (GFC, ). Despite the voluntary character of the BMP principles, compliance is high in Southern pine silviculture (Fox et al ., ).…”

Streamside Management Zones Effectiveness for Protecting Water Quality after Forestland Application of Biosolids

“…We applied biosolids to a total of 3.5 ha of loblolly pine stands adjacent to the three streams at a rate of 1120 and 629 kg ha −1 of total N and total P, respectively, which provided 268 and 68 kg ha −1 of plant‐available N and plant‐available P, respectively (Evanylo, 1999b). The target application rate was to provide 224 kg of plant‐available N ha −1 , which is the standard N fertilization rate for intensively managed loblolly pine plantations (Fox et al, 2007). The typical mid‐rotation P fertilization rate for intensively managed loblolly pine plantations is 28 kg ha −1 (Fox et al, 2007).…”

“…The target application rate was to provide 224 kg of plant‐available N ha −1 , which is the standard N fertilization rate for intensively managed loblolly pine plantations (Fox et al, 2007). The typical mid‐rotation P fertilization rate for intensively managed loblolly pine plantations is 28 kg ha −1 (Fox et al, 2007). Phosphorus applied exceeded recommended P rates for loblolly pine due to the N/P ratio of biosolids.…”

“…In the south, many soils become limited in nitrogen (N) and phosphorus (P) as stands mature. Fertilizing intermediate‐age loblolly pine ( Pinus taeda L.) stands on N‐ and P‐limited soils improves tree growth, which reduces rotation times, increases profits, and allows fiber production on a decreased land base (Fox et al, 2007). However, fertilizer prices are increasing, causing decreased financial returns from conventional fertilization and encouraging forest managers to seek less expensive alternatives (Albaugh et al, 2007).…”