Cover Crops and Humus 
E. F. DeBusk, Tavares 
The difference between some of our 
good citrus soils and a mass of sand lies 
in the amount of organic matter in the 
former. The sand is the frame-work; the 
organic matter is the material that cements 
the frame together into a structure that 
functions. 
We have what is known as active and 
inactive organic matter. The latter is 
usually known as humus, but this paper 
will treat to some extent organic matter 
in its various forms, and relations to crop 
production. 
Organic matter in the soil is essential 
to crop production in general. This is 
fundamental, and no less true in the pro¬ 
duction of citrus fruits. It is generally 
conceded that most of our Florida citrus 
soils are lacking in this essential soil con¬ 
stituent. I shall discuss briefly how and 
to what extent this deficiency of organic 
matter affects maximum production of 
citrus fruits, and how this integral con¬ 
stituent of our citrus soils may be supplied 
most economically. Technical discussions 
of the subject will be avoided as far as 
possible. 
Let us consider the correlation of the 
organic matter in our soil with: (i), its 
physical condition; (2), the chemical 
change that takes place; (3), its bacterial 
flora. In this brief paper the last two 
divisions must come under one discussion. 
During the drought through which we 
are just passing, attention has been called 
very forcefully to the relative water-hold¬ 
ing capacity of the same type of soil in 
different groves and under different soil 
managements. The fact that organic 
matter increases the water-holding power 
of our citrus soils has been clearly dem¬ 
onstrated, and needs only to be stressed at 
this psychological time. Failure on the 
part of many of our growers to prepare 
for these occasional droughts has cost the 
fruit industry many thousands of dollars 
in loss of fruit and withered trees. While 
these droughts come so few and far be¬ 
tween that they scarcely make an impres¬ 
sion, still at the same time many of our 
growers lose fruit and growth every 
spring that could be saved if more atten¬ 
tion were given to building up the organic 
content of the soil. The sand particles of 
our soils can hold but very little capillary 
moisture, the kind of moisture that our 
trees depend upon. The more decaying 
organic matter that can be added to this 
frame-work of the soil, the greater the 
percentage of capillary water over that of 
the hygroscopic water, and consequently 
the greater the percentage of the total wa¬ 
ter content of the soil that can be delivered 
to the growing crop. Organic matter, 
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