A Cover Crop Program for Florida Pecan Orchards


and C. spectabilis. Oats followed by C. spectabilis gave the least
tonnage of organic material, although C. spectabilis made a
heavier growth in this plot than in those where the winter
legumes were grown. Crotalaria spectabilis could not make
maximum growth in any plot due to the shading of the ground
by large trees.
 The trees responded to leguminous cover crops and sulfate
of ammonia and gave significant increases in growth and yields.
Yields during the first four years were quite low, but for the
three years following they were higher by 292 to 556 percent
for Frotscher and 78 to 204 percent for Stuart. Frotscher
produced much heavier crops than Stuart and consequently gave
much greater returns above cost of materials.
 The combination of oast in winter and C. spectabilis in summer
failed to increase nut production and gave unsatisfactory results.
In fact, nut production during 1932 to 1934 was better in each
section of the unplanted plot than where oats were grown,
except with the Stuart in one instance.
 There were no significant differences in sizes and kernel per-
centages of nuts produced under conditions maintained in the
various plots. Therefore, growers may follow a program of
cover-cropping and fertilization, such as the one giving the
highest yield in the experiment, without fear of impairing the
size and quality of the nuts.
 The nitrogen content of the surface soil in the experiment
increased where cover crops were grown and decreased with
a natural growth of native non-legumes. The organic content
of the surface soil during the period of the experiment showed
a decrease in the unplanted plot and in one plot where the cover
crops were grown, while the other two planted plots showed
slight increases. Sudan grass produced heaviest growth on soils
from hairy vetch Plot 2, second from Austrian peas Plot 1, third
from oat Plot 4, and lowest from the unplanted Plot 3. Pecan
yields where either Austrian peas or hairy vetch were grown
followed by C. spectabilis were in agreement with the Sudan
grass growth.
 Results obtained in this experiment would indicate that a
profitable program to follow in bearing pecan orchards located
on suitable soils, such as the one worked with, would be to grow
winter and summer legumes. Such a program would consist
in the planting of hairy vetch, Austrian peas or some other
legume which would make comparable growth during winter,