A Cover Crop Program for Florida Pecan Orchards 13

 by these conditions and produced a moderately good crop of nuts
 in 1932, which was heavier in corresponding parts of the planted
 plots than where no cover crops were grown. Yet, under these
 adverse conditions the data in Table 4 show that trees in the
 plots where the winter and summer legumes had been grown
 and returned to the soil for four years gave the highest pro-
 duction.
 The majority of Stuart trees in the experiment developed
 varying amounts of rosette after the experiment was started,
 doubtless reducing yields of this variety to a marked degree.
 While this condition contributed materially to the low produc-
 tion, it probably was not the sole cause, as trees of the Stuart
 variety did not respond to fertilizers in other experiments (3)
 as satisfactorily as some other varieties. The rosette, however,
 was not caused by treatments given to any of the plots, as it was
 general and could be traced to other factors operating prior to
 the period of the experiment.

 CULTIVATION OF EXPERIMENTAL AREA
 All plots were cultivated by either disking or shallow plowing
each fall in preparation for planting winter cover crops. The
soil was again disked each spring except in years when there
was an exceptionally heavy growth of winter crops; at such
times the plants were allowed to die down and form a mulch
over the soil, and no cultivation at all was given to any of the
plots. The heaviest mulch was made by hairy vetch, the second
heaviest by Austrian peas, while the oat mulch was almost as
scanty as the covering produced by the native growth of weeds
and grasses in the check plots. The hairy vetch was very dense
in 1931, giving a mulch so completely covering the surface of
the soil that even the growth of nut grass was materially re-
tarded. However, the C. spectabilis, due to a thin stand of
plants, made a poor showing during the summers when the land
was left uncultivated in the spring.
 Cultivation was handled in this manner because it seemed
better to have a mulch on the land whenever possible rather
than to clean cultivate the area; in so doing it was necessary
to leave the check and non-legume plots undisturbed so that the
soil would receive the same treatment in all plots. This pro-
cedure proved to be extremely beneficial for the hairy vetch
plot, but it was not so advantageous in the non-legume and check
plots and for the growth of the summer legume.