Evaluation of Soil Testing Methods for Predicting Growth and Response of Pinus elliottii to Phosphorus Fertilization1
- R. Ballard and
- W. L. Pritchett2
Soil tests were evaluated as methods for predicting height growth or increased height growth due to P fertilization of Pinus elliottii var. elliottii Engelm. on acid Coastal Plain soils. Growth and response parameters were obtained from field and greenhouse trials fertilized at time of planting with N and P. Field trials were measured 1, 3, and 5 years after planting and the greenhouse trial, which involved unfertilized soils collected from the field trials, was measured 1 and 2 years after planting.
The amounts of P extracted by H2O or NH4OAc (pH 4.8) were the most closely correlated with height growth and response to P fertilization after 1 year of growth in both the greenhouse and field. The effectiveness of these methods declined after longer growth periods. Methods which extracted larger amounts of P—0.5M NaHCO3; 0.05N HCl + 0.025N H2SO4; 0.03N NH4F + 0.025N HCl—were more effective predictors of response to P fertilization over growth periods of 3 and 5 years in the field. Phosphorus extracted by 0.03N NH4F + 0.025N HCl was the most closely correlated with response recorded after 5 years (r2 = 0.778).
Concentrations of P in the tops of greenhouse-grown pine seedlings after both 1 and 2 years growth were most closely related to P removed by the stronger extractants. The r2 values for the relationships between soil test values and both concentrations of P in seedling tops after 2 years and in foliage of field trees at age 4 were almost identical.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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