Response of Slash Pine (Pinus elliottii Engelm. var. elliottii) to Phosphorus in Sandy Soils1
- W. L. Pritchett and
- W. R. Llewellyn2
Rock phosphate or superphosphate band applied to slash pine about 1 year after transplanting resulted in significant height and diameter increases in 5 of 8 experiments, 3 to 5 years after treatment. However, response occurred only on somewhat poorly to poorly drained (flatwood) sands of the Groundwater Podzol and Humic Gley groups. While 50 lb N/acre applied alone usually suppressed tree growth, when applied in combination with 35 lb P/acre, it resulted in additional response. After the third year, 140 lb P/acre from rock phosphate gave about as good results as 35 lb P/acre from superphosphate. The optimum level of tissue P in current needles of 3- to 5-year-old trees was approximately 0.10%. Total soil P did not appear to be of much value for predicting response of young pine trees to added P. However, the amount of P extracted from unfertilized surface soil with 1.0N NH4OAc (pH 4.8) was negatively correlated with response to phosphate applications on flatwoods sands. Curvilinear regression lines in relation to tree response to varying levels of fertilizer P with amounts of soil extractable P were constructed.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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