SOIL STUDIES
 By W. G. Blue

 Methods
 Sampling procedures.-Soil samples (0- to 6- inch depth)
were collected annually within a 30-foot radius of permanent
posts placed at random within pasture subdivisions. Ten cores
were composite for each sample. This procedure tended to re-
duce the effect of natural soil variation and permitted measure-
ment of changes that occurred as a result of experimental treat-
ments. Thus, 20 samples were collected annually from Program
1, 34 from Program 2, and 16 from Program 3. The samples
were dried, screened, and analyzed by the Cooperative Extension
Service Soil Testing Laboratory. Soil p1H was measured in a 1:2
volume soil: water suspension. Soil K, P, Ca, and Mg were ex-
tracted by ammonium acetate (pH 4.8) using 5 g of soil and 25
ml of solution. Phosporus was determined colorimetrically, K by
flame emission spectrophotometry, and Ca and Mg by atomic
absorption spectrophotometry.
 Plant analyses.-Plant samples from the first, fourth, and
sixth cage harvests in 1971 as collected and prepared by Agron-
omy Department personnel were analyzed to determine adequacy
of soil nutrients and fertilizer treatments for plant mineral nu-
trition. One-gram samples were dry-ashed at 450 C for a mini-
mum of 4 hours. The ash was dissolved in 5 N HC1, taken to dry-
ness to dehydrate Si, and redissolved in sufficient 5 N HC1 to give
50 ml of 0.2 N solution. Phosphorus was determined colorimetri-
cally; K by flame emission spectrophotometry; Ca, Mg, Mn, Cu,
Zn, and Fe by atomic absorption spectrophotometry; and S gravi-
metrically.
 Availability of accumulated nutrients.-Since some nutrients,
including P and the micronutrients, are known to accumulate in
flatwoods soils (Spodosols) from fertilization, particularly after
liming, a small-plot experiment was superimposed on these
grazed programs in early 1971, to measure availability of ac-
cumulated nutrients. Five treatments were located in each of
four pastures replicationss) on the experimental area. These
were fenced to prevent contamination from cattle and were cov-
ered with a plastic sheet briefly in the fall to eliminate the effects
of general pasture fertilization. Treatments from 1952 through
1970 included periodic liming and micronutrient applications,
and annual application of P, K, and S. Initially 2 tons of calcitic