Historical Patterns of Forest Fertilization in the Southeastern United States from 1969 to 2004

摘要

Based on historical forest fertilization survey records, over 16 million ac were fertilized in the southeastern United States from 1969 to 2004, with the peakforest fertilizer application in 1999, when 1.59 million ac were fertilized. The 1999 applications were largely on loblolly pine (Pinus taeda L; 91%) in establishedstands (78%) and included both nitrogen and phosphorus, typically as urea and diammonium phosphate fertilizers, respectively. On a tonnage basis from 2000to 2004, the average amount of forest-applied urea and diammonium phosphate represented 2.5% of those materials applied in the United States. The numberof acres fertilized approximately doubled every 2 years from 1991 through 1999. This increase can be attributed to a shift in forest production interests tothe southeastern United Stales at a time when research results were showing positive biological and economic responses to nitrogen and phosphorus applicationsin midrotation southern pine stands. Common application rates for nitrogen and phosphorus were 200 and 50 Ib elemental nitrogen ac~(-1) and 25 and 50 Ibelemental phosphorus ac~(-1) for stands >2 years old and <=2 years old, respectively. In 1994, application of elements other than nitrogen and phosphorus,including potassium, boron, and magnesium, began in response to newly available research results. Boron was applied to 30% of the total number of acresfertilized in 2004, likely because boron, when applied with urea, may reduce nitrogen volatilization.