DEPARTMENT OF AGRICULTURE 21

 Figure 11 shows the effect of different rates of fertilizers
and plants per acre. Sixteen hundred pounds of fertilizer per
acre with 6200 plants was best on this particular soil type
which was a Norfolk fine sand deep phase.
 Recent tests with irrigation shows that there is little need
to increase the rate of fertilizer when irrigation is used prop-
erly. Excessive rates, when used with irrigation, result in
lower quality as is the case without supplemental water. These
conclusions are based on the assumption that irrigation rates
are not excessive. The following fertilizer sources and rates
are recommended:
 Nitrogen: The level of available nitrogen is probably more
difficult to control within desired limits than is the case with
the other nutrients. Nitrogen is closely associated with many
of the constituents of quality. A low nitrogen level will result
in a low yield and value. (See figure 8) On the other hand,
however, over-fertilization with the element has resulted in
the production of a tobacco with undesirably high amounts
of nicotine and other nitrogenous compounds, low in sugar,
off in color and of poor quality in general.
 The amount of organic matter in the soil is important in
determining the amount of nitrogen that should be used, how-
ever, most of the soils used in growing tobacco in Florida
are low in organic matter. It is necessary to distinguish be-
tween the soil types to the amount of nitrogen used. On the
average from 36 to 48 pounds of nitrogen, including both the
preplanting and sidedress fertilizer is recommended for to-
bacco. The optimum rate is often governed by the soil type,
previous cropping practices and weather conditions during
the growing season. The rate may be increased on the very
sandy soils and on soils lower in organic matter, and decreased
on the sandy loam soils higher in organic matter.
 On heavier textured, more fertile soils, and where tobacco
has a tendency to be rough and of poor quality, the nitrogen
should be reduced to 24 to 36 pounds per acre depending upon
the fertility of the soil.
 Tobacco should not be grown directly after a legume since
it is difficult to predict the amount of nitrogen needed in the
commercial fertilizer under this condition. The time and rate
of liberation of nitrogen from the decomposing legume plant