A Cover Crop Program for Florida Pecan Orchards 9

ammonia was applied annually in June or July to half of each
plot beginning with 1930. This was done for the purpose of
testing its effects on tree growth and yield when used on soils
under different cover-crop management. Superphosphate and
sulfate of potash were applied to all plots annually in the fall.
 The block of Frotscher (Fig. 2) and Stuart (Fig. 3) selected
for the tests is located in Jefferson County. The land is only
slightly rolling with no appreciable erosion and is classified as
Norfolk fine sandy loam. This type is commonly planted to
pecans in the area. The trees were set 17 to the acre in 19044
and were therefore 23 years old when the experiment was
initiated in 1927. They were rather uniform, although they had
been in low production for several years prior to 1927 when there
were no planted cover crops grown and little or no fertilizers
applied.
 PLAN OF EXPERIMENT
 After it had been determined which winter and summer cover
crops would make best growth, the experiment was planned to
test their value in pecan orchards. The work was started in
1927. In the experimental area were 144 trees planted 50 by 50
feet, but records were kept on the behavior of only 42 Frotschers
and 42 Stuarts, the others being used as buffers between the
cover-crop plots.
 The block of trees was divided into four plots for each variety,
three planted to cover crops and one used as a check where
nothing was planted. The planted plots each contained 12
Frotscher and 12 Stuart trees originally, and the unplanted plot
six of each variety. In 1930 all plots were divided equally into
two sections, A and B; with this arrangement there were six
trees of each variety in the corresponding parts of the planted
plots and three in the unplanted. Austrian peas (Fig. 1), hairy
vetch (Fig. 4), and oats (Fig. 5) were grown on the cover-
cropped Plots 1, 2 and 4 during the winter and C. spectabilis
during the summer. No crops were planted on Plot 3 either
winter or summer (Figs. 6 and 7). The following amounts of
seed in pounds per acre were planted annually in the experiment:
Hairy vetch 20, Austrian peas 30, oats 64, rye 60, and C. spec-
tabilis 6 each in 1928 and 1931 only, as it volunteer all other
years. The initial planting of the cover crops was made in 1927
and growth and yield records started in 1928.

 4 This date was given as 1908 in former published articles.