relatively constant from 1965 through 1972 (Table 6). Addi-
tional lime, surface applied in 1967, increased soil pH although
there was relatively little effect on extractable Ca and Mg.
During Phase 2 of this study, it was demonstrated that lime was
concentrated at the soil surface as a result of surface applica-
tion, and much of this was undoubtedly not extracted by the
ammonium acetate.
 Extractable P did not change appreciably except that it was
substantially lower in the fall of 1972. Total soil P analyses from
this experiment and supplementary laboratory studies (3) in-
dicated that applied P accumulated in the surface soil. This is
known to occur as soil pH is increased (11). Laboratory data
indicated that about 60% of the P applied at rates used in the
field study would be retained in the surface soil if the pH were
maintained at 6.0. Total P analyses of field samples confirmed
that approximately this percentage was retained. This accumu-
lated P was shown to be available to white clover and Pensacola
bahiagrass (13). Response to applied P in greenhouse pot ex-
periments was nil when soil contained 600 pounds per acre of
total P; response to currently applied P was small for soils with
300 pounds per acre. Unfortunately, neither P extracted by am-
monium acetate (pH 4.8) nor by the Bray-Kurtz No. 1 reagent
(0.03 N NH4F + 0.025 N HC1) was related to total P. Stronger
extractants such as Bray-Kurtz No. 2 (0.03 N NH4F + 0.1 N
HC1) have not been tested.
 Potassium extracted from surface soil varied slightly among
years, but it did not differ drastically from concentrations in vir-
gin soils (45 pounds per acre) even though at least 1,300 pounds
of K per acre were applied between 1952 and 1972. Supplemen-
tary studies indicated that there was some K retained in the soil
throughout the rooting zone though there was no horizon where
K was concentrated. This accumulated K was absorbed by deep-
rooted grasses (4), but it would be of limited value to white
clover, since this plant apparently requires a higher K concen-
tration in the surface soil for its annual re-establishment from
seed. The CEC which is largely responsible for retention of the
basic nutrients is derived primarily from organic matter in
these surface soils. Cation exchange from organic matter is pH
dependent; i.e., it increases as pH is increased. Theoretically,
elevation of soils pH to 6.0 would increase the capacity of the
soil to retain K; however, liming to increase soil pH also adds
Ca and Mg which act as competing ions. These ions are held
more strongly than K and in effect exclude K from the exchange