A Cover Crop Program for Florida Pecan Orchards


in the different treatments. The average annual yields per
tree are shown for the different plots, and were calculated to
an acre basis of 17 trees. They are pictured graphically in Fig.
15 to show more clearly the effects of the cover crops and the
fertilizers.
 Production of each variety during 1928-1931 did not vary
greatly with different soil treatments. There was a slight ad-
vantage in the legume plots but it was not significant, since the
differences were almost the same as those shown for the first
record in 1928.
 By examining the data presented in Table 4 it will be noted
that nut production under all treatments averaged relatively
low for both varieties during the first period of 1928 to 1931.
For the second period of 1932 to 1934, however, the average yield
of Frotscher amounted to 35.3 and 34 pounds per tree without
sulfate of ammonia where Austrian peas and hairy vetch were
grown, but with sulfate of ammonia trees on soils growing the
same cover crops produced 56.9 and 57.1. Therefore in the two
all-legume plots the increase for the second period over the first
amounted to over 400 pounds per acre with superphosphate
and sulfate of potash only, and more than 750 pounds where
nitrogen, phosphoric acid and potash all were applied. These
increases were rather significant and clearly show the value of
maintaining soil fertility with the use of legumes in both winter
and summer, since yields were decidedly higher with leguminous
cover crops than in the other plots.
 The data in Table 4 show that Stuart, though lower in pro-
 duction, followed the same general trends as the Frotscher.
 Tree yields consistently increased during the second period over
 the first where the winter legumes and crotalaria were grown
 in comparably fertilized sections.
 There were only slight differences in production of trees
under various treatments during the first period. However,
it can be observed in Table 4 that during the second period the
trees growing where winter and summer legumes were returned
to the soil produced consistently heavier than where no cover
crops were planted. The combination of oats in winter and
Crotalaria spectabilis in summer as green manure crops returned
to the land failed to give satisfactory results, and except in one
instance trees in this plot produced fewer nuts than where only
native vegetation was returned to the soil.