A Cover Crop Program for Florida Pecan Orchards 17

weight for C. spectabilis with Plots 2 and 1 second and third.
The average annual amount of green material returned to the
soil was relatively high for C. spectabilis and either Austrian
peas or hairy vetch in Plots 1 and 2, but for C. spectabilis and
oats in Plot 4 it was rather light, due to the sparse growth of
the oats.


 Fig. 8.-Nodules on the roots of hairy vetch (left) and Austrian peas.

 Average analyses of these crops shown in Table 2 do not
represent samples from this experiment, but are compiled from
data for like materials accumulated over a period of years by
the Department of Chemistry and Soils of this Station. These
show that in each ton of oven-dry material there were about
43 pounds of nitrogen in Austrian peas, 62 pounds in hairy vetch
and 29 pounds in Crotalaria spectabilis. Thus most nitrogen
was returned to the soils by hairy vetch and crotalaria in Plot 2,
second by Austrian peas and crotalaria in Plot 1 and third by
one crop of hairy vetch grown the first year of the experiment
and the C. spectabilis in Plot 4 (Fig. 8).