Fertilizer Responses in Young Pine Plantations
1972
Pritchett, W. L. | Smith, W. H.
Regional fertilizer trials were installed in 28 young pine plantations in the US Lower Coastal Plains in 1968. Three randomized complete blocks consisting of a 3² + 2 factorial experiment were included at each site. Soil samples were collected to help characterize the sites physically, chemically, and biologically. Site preparation, planting and fertilization methods were uniform from site to site. Survival was influenced by site properties and fertilizer treatment. On well-drained sites N reduced survival. Height growth response varied from none on dry sands to as much as 130% increase on some wet sites. Nitrogen significantly affected tree growth in 53% of the tests; but on P deficient sites, N applied alone had little influence on tree growth. Phosphorus additions increased growth in 63% of all tests and 82% of the tests located on poorly-drained sands. The number of trees damaged by tip moths (Rhyacionia spp) averaged 10% or more in only 18% of the tests. In these experiments, P and K applications apparently reduced the number of trees attacked. Almost 22% of the trees in all tests were infected with Cronartium fusiforme Hedge. However, 40% of the tests had less than 5% infection. In tests where rust was severe, the percentage of rust-infected trees increased with fertilization. Fertilization, especially with K, appeared to reduce insect attacks. Species composition of the ground cover was altered by treatments.
显示更多 [+] 显示较少 [-]