Florida Agricultural Experiment Stations


have shown the importance of a balanced fertilizer for the pro-
duction of high yield of tobacco. As a result of research with
fertilizer ratios and rates of application, the Southern Agronomy
Research Committee for flue-cured tobacco (10) has recom-
mended rates of 800 to 1,200 pounds of fertilizer per acre. For
the more productive soils 800 to 1,000 pounds of fertilizer con-
taining 3 percent nitrogen, 10 percent phosphoric acid and 6 to
10 percent potash were recommended by the committee. For
the lighter soils 1,000 to 1,200 pounds of a mixture analyzing
3 percent nitrogen, 8 to 10 percent phosphoric acid and 6 to 10
percent potash were recommended. In addition, this committee
has recommended that the fertilizer for flue-cured tobacco should
contain 2 percent magnesium, 2 percent chlorine and not less
than 6 percent calcium (CaO). Sulfur (SO) is essential, but
large quantities of easily-soluble forms should not be used.
 The average yield of tobacco in Florida for a 10-year period
1940-49 (7) was 920 pounds per acre. One of the factors that
limits high production is the lack of rainfall during the peak
growing season. (See Figure 1.) Weather records (6) show
that the annual rainfall at Gainesville has varied from 31 to 65
inches. Because of rainfall variability, it has been very difficult
to raise the average yield beyond 1,100 pounds per acre.
 McMurtrey (22) and Darkis (8,9) found that adequate soil and
air moisture are cardinal requirements for the growth of good
leaf tobacco which meets exacting commercial demands. When
high rates of fertilizer are used and low rainfall occurs, a poor
quality of leaf is produced. These authors state further that
leaf produced during a dry season is dull in color, high in nico-
tine and lacking in elasticity. The tobacco has more aroma,
which is associated with gums and resins. It also has a dense
structure with a high weight per unit of leaf area and a low
fire-holding capacity. The leaf ferments or ages slowly. On
the other hand, high quality tobacco is commonly produced during
a season with an adequate amount of well distributed rainfall.
The leaf is thin, light in weight per unit of leaf area, low in nico-
tine, weak in aroma, brighter in color and low in gums and
resins, and shows an active fermentation when bulked.
 Garner (16) states that for normal and rapid growth in the
 field, tobacco requires well-distributed rainfall, or its equiva-
 lent in irrigation. The water requirements of the plants are
 high because of the expanse of foliage. He reported that the to-
 bacco plant is sensitive to excessive water and will drown if the
 soil remains waterlogged for too long a time. An excess of mois-