@article {Bengtson:1976:0015-749X:487,
	author = "Bengtson, G. W.",
	title = "Comparative Response of Four Southern Pine Species to Fertilization: Effects of P, NP, and NPKMgS Applied at Planting",
	journal = "Forest Science",
	volume = "22",
	number = "4",
	year = "1976",
	abstract = "Seedlings of sand, slash, loblolly, and longleaf pine planted on an intensively prepared, excessively well-drained Sandhills site in west-central Florida were treated immediately after planting with varied rates and schedules of application of P, NP, and NPKMgS fertilizers. Nitrogen-phosphorus fertilizers, especially at the highest rates, reduced survival of all four species below that of the controls. But in sand and slash pine, inclusion of KMgS (as potassium-magnesium sulfate) with the NP fertilizer negated this effect. Three years after fertilization was started, survival of longleaf pine (59 percent) was significantly lower than that for sand (86 percent), slash (88 percent), and loblolly pine (91 percent). Longleaf survival was also most adversely affected by heavy NP fertilization. None of the four species showed significant growth response to P or NP fertilizers, but height growth increases of 25 percent for sand, 16 percent for slash, 28 percent for loblolly, and 17 percent for longleaf pine were recorded after 3 years when KMgS was applied with the highest rate of NP fertilizer. Foliage collected 3 years after fertilization showed significant differences in concentration of N, P, K, Ca, Mg, and S associated with tree species and differences in P, K, and Ca related to fertilizer treatment. But only the substantial and highly significant increase in foliage K observed for all four species following application of the N<SUB>2</SUB>P<SUB>2</SUB>KMgS treatments appeared causally related to fertilizer-stimulated growth. The data suggest that on this site, and perhaps on similar intensively prepared Sandhills sites, K deficiency limits the growth potential of these four species and their capacity to respond to NP fertilizer. This deficiency is manifest in young trees by dormant-season foliage K concentrations below 0.30 percent. Concentrations in the range 0.35 to 0.40 percent appear to reflect K sufficiency in all four species. Species height ranking over all fertilizer treatments at 3 years from planting was sand &#62; slash &#62; loblolly &#62; longleaf. Forest Sci. 22:487-494.",
	pages = "487-494",
	url = "http://www.ingentaconnect.com/content/saf/fs/1976/00000022/00000004/art00026",
	keyword = "Sand pine, slash pine, loblolly pine, longleaf pine, critical nutrient levels, foliage analysis, species comparisons"
}