Six-year growth of Eucalyptus saligna plantings as affected by nitrogen and phosphorous fertilizer

Abstract

Growth responses of Eucalyptus saligna to nitrogen (N) and phosphorus (P) fertilizers were assessed in bioenergy plantations on abandoned sugarcane land in Hawaii. Fertilizers were applied three times (0, 6, and 15 months after planting) in a factorial design with four dosages each of N (0, 25, 50, and 75 g urea per tree) and P (0, 30, 60, and 90 g triple superphosphate per tree). Phosphorus and the N x P interaction had little effect on tree growth. Effects of N, however, were dramatic during the first year, and benefits were sustained through 6 years. Trees treated with 25 g urea were twice as tall, twice as large in diameter, and produced four times as much biomass per ha as untreated trees. Compared with trees treatcd with 25 g urea. Trees treated with 50 g and 75 g urea were 35 to 45 percent larger in diametear and height and produced twice as much biomass per ha. Effects of N on height growth and diameter growth dropped markedly during the third year and thereafter. Survival and uniformity of tree size were also increased by N fertilizer. Bioenergy plantations of E. saligna established on similar sites and soils will benefit from high dosages of N fertilizer and presumably from repeated applications.

Citation

Whitesell, Craig D.; DeBell, Dean S.; Schubert, Thomas H. 1987. Six-year growth of Eucalyptus saligna plantings as affected by nitrogen and phosphorous fertilizer. Res. Pap. PSW-RP-188. Berkeley, CA: U.S. Department of Agriculture, Forest Service, Pacific Southwest Forest and Range Experiment Station. Revised 1988. 5 p