Gh. Korndorfer et al., PHOSPHORUS SOIL TEST CORRELATION TO SUGARCANE GROWN ON HISTOSOLS IN THE EVERGLADES, Soil Science Society of America journal, 59(6), 1995, pp. 1655-1661
Sugarcane (Saccharum spp.) in Florida is principally grown on Histosol
s in the Everglades Agricultural Area. Soil-test-based P fertilization
recommendations have not been addressed since the 1970s. The objectiv
es of this research were to evaluate the most acceptable soil test P e
xtractant that best correlates to crop yield, and to define soil test
P groupings associated with crop response to applied P. Results will b
e used in the future to recalibrate soil test data to yield and rate o
f P application. Phosphorus trials were conducted at four sites on org
anic soils between 1968 and 1972 and additionally at eight sites on or
ganic soils between 1982 and 1990. Phosphorus applications ranging fro
m 0 to 98 kg P ha(-1) were broadcast or row-applied in combination wit
h different cultivars, and/or K, Si, or S rates at 12 sites (multiple
experiments used per site per crop). The effectiveness of water, aceti
c acid, and Mehlich-1 extractable soil P as yield response predictors
was determined. Acetic acid extractable P was more highly correlated t
o sugar and cane yields (r = 0.72 and 0.63**, respectively) than wate
r-extractable P (r = 0.27* and 0.39**, respectively). Mehlich-1 extra
ctable P was poorly correlated to sugar (r = 0.25) and cane (r = 0.05
(ns)) yields. Acetic acid extractable P was selected as the best-suite
d extractant related to crop yield response to P fertilization. Soil t
est calibration curves (i.e., relative yield as a function of acetic a
cid extractable P) were determined from the choice of seven types of r
egression models, in which the reciprocal function was chosen with the
highest coefficient of determination (R(2)) and minimized residuals.
Soil acetic acid extractable P criteria were developed to define soil
test level groups associated with yield response conditions: low soil
test levels ranged from 0 to 9 mg L(-1), medium from 9 to 39 mg L(-1),
and high exceeded 39 mg P L(-1).