| Abstract: | Abstract Bray P2, Mehlich 1, and Mehlich 2 methods identified soils on which loblolly pine would respond to P fertilizer in a greenhouse study using six soils from the West Gulf Coastal Plain. The P extracted by any of the three methods did not correlate with growth on unfertilized soils or to the maximum amount of response when P was applied. Phosphorus sorption curves were used to estimate the amount of P in soil solution. The concentration of P in roots and tops was proportional to the log of the amount of P in solution. For 90% of maximum dry weight of loblolly seedlings, about 0.22 mg/liter of P in soil solution was necessary. The phosphorus sorption method has the potential of predicting the P requirements of loblolly pine, but field testing is necessary. |
