Bulletin 229, Diseases of Citrus in Florida


money but greatly expedites the destruction of the organic mat-
ter in the soil and coarsens the texture of the fruit.
 Cultivation is rarely practiced in Florida groves on low ham-
mock land, since it is more often necessary in such situations to
get rid of water than to conserve it. The present recommenda-
tions on most lands except the low hammocks are to cultivate
only sufficiently during the dry season of the year to keep down
the growth of grass and other weeds that may compete with
the tree roots for moisture and to grow leguminous cover crops
during the rainy season. With an irrigation system to take care
of the moisture requirements of the trees, mowing can largely
replace cultivation, even on high land, except for what culti-
vation may be necessary to work in cover crops to reduce the
fire hazard.
 Importance of Organic Matter in the Soil:-In Florida, where
 there is a preponderance of light sandy soil with relatively little
 or virtually no organic matter to begin with, the supply, under
 existing conditions, tends to become destroyed rapidly, even
 under a rational system of cultivation. The bacterial decompo-
 sition of organic matter in such soils is very rapid, owing to their
 porous condition, the high temperatures prevailing, and the
 heavy rainfall. It is evident, therefore, that one of the greatest
 benefits that can come to the Florida citrus industry would be
 for growers to realize the necessity of growing green manurial
 cover crops, especially legumes, as a means of enriching their
 soils and replenishing the supply of organic matter. While com-
 mercial fertilizers may put back into a soil certain elements that
 the trees and fruit crops remove, unless good cover crops are
 grown or vegetable matter is hauled into the groves, growers are
 not putting back into the soil the organic matter that is being
 destroyed by cultivation, with the result that the problem of
 grove maintenance increases each year.
 An abundance of organic matter is required for the develop-
 ment of the beneficial soil bacteria and the maintenance of bio-
 logical activity in the soil. The presence of organic matter is
 likewise beneficial in that plant food is made soluble by the ac-
 tion of the organic materials on the soil constituents. Continu-
 ous clean cultivation, however, tends to sterilize the soil and
 the too often scanty supply of organic matter originally present
 becomes burned out gradually by oxidation, with the result that
 the soil is ultimately changed into a lifeless mineral mass, on