Group Title: Press bulletin
Title: Humus as a soil improver
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 Material Information
Title: Humus as a soil improver
Alternate Title: Press bulletin 121 ; Florida Agricultural Experiment Station
Physical Description: 2 leaves : ; 21 cm.
Language: English
Creator: Blair, A. W ( Augustine Wilberforce ), b. 1866
University of Florida -- Agricultural Experiment Station
Publisher: Florida Agricultural Experiment Station
Place of Publication: Gainesville, Fla.
Publication Date: July 31, 1909
Subject: Humus -- Florida   ( lcsh )
Soil management -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
Statement of Responsibility: by A.W. Blair.
General Note: Caption title.
General Note: "July 31, 1909."
 Record Information
Bibliographic ID: UF00090482
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 82158736

Full Text


Florida Agricullural Experimenl Salion

The dark-colored material that we call humus consists of partly decayed
organic matter, either animal or vegetable. Stubble, grass, roots, cornstalks,
cotton stalks, and the like, are not humus; but these materials when turned
under the moist soil soon begin to decay and fall to pieces, and it is
then that humus is formed. This process of decay and humus formation
goes on as long as the conditions are favorable and there is any organic
material left. Humus may be called an intermediate product, for under
favorable conditions the process of decay goes on until there is no longer
any vegetable or animal substance left, nor yet any humus; but instead,
water, gases that escape into the air, and a small amount of mineral mat-
ter. We thus see why it is that we need to renew the supply of humus
from time to time. If a crop of velvet-bean vines is turned under in the
winter or early spring, and an examination is made in April or May, much
of this decaying matter or humus will be found. If now a crop of corn
or cotton is grown during the summer, and the land thoroughly cultivated,
it is probable that none of the humus would be seen if an examination
should be made in September. It does not follow, however, that all the
Shumus has been used up, but it has been so thoroughly incorporated with
the soil that the eye does not detect it, except that the land would look
darker. During all the time the humus was gradually being transformed into
simpler compounds, it was serving its purpose.
The Uses of Humus

Humus improves the mechanical condition of the soil, by making it looser
and mellower; it increases the water-holding capacity, and thus the plant-
food holding capacity of soil; it furnishes food for useful micro-organisms,
which in turn convert the nitrogen of the organic matter into a form that
is available for the crops; it aids in bringing into solution difficultly soluble
minerals that contain plant food; and it yields a small amount of mineral
plant food itself.
If one would get a good idea of the value of humus, he need only com-
pare fields where a legume crop has been grown as part of a system of ro-
tation, and where stable manure has been used liberally, with those fields
where corn and cotton have been grown steadily year after year on com-
mercial fertilizers. The latter are devoid of humus, and have lost much

July 31, 1909

of their power of holding water and plant food. The value of humus is
also emphasized where an old Larn or house has been left standing in the
middle of a field. Around these the crops are usually much superior to
those on the surrounding portions of the field.
Humus and Sandy Soils
Sandy soils, on account of their open, leachy condition, are especially
in need of a good supply of humus. Furthermore, the conditions in Florida
favor a rapid disappearance of the humus. This "burning out" of the
humus is caused by certain bacteria, and whatever is favorable to their
development hastens the destruction of the humus. Warmth, moisture, and
a good supply of air are conditions which favor bacterial development; and
since these conditions are fulfilled to an unusual degree in Florida, it follows
that the humus will disappear with more than ordinary rapidity. In such
soils it is necessary to supply humus-forming materials more often than
it is in a heavy clay soil.
This loss of humus is compensated for by the production of nitrates
as the humus disappears. Analyses of some pineapple soils have shown
that samples taken from surfaces where vegetable matter is decaying, are
much richer in nitrates than those taken from clean bare surfaces, or from
the subsoil where there is but little organic matter.
How Humus May Be Increased
The growing of leguminous crops is one of the best ways to increase
humus, for in this way nitrogen also is added to the soil. Among the Flor-
ida crops which are suitable for this purpose may be mentioned the velvet
bean, beggarweed, and cowpea. Humus may also be increased by a more
general and liberal use of stable manure, and by turning under stubble,
weeds, or grass, instead of burning them. When these materials are burnt,
nitrogen is lost as well as humus.

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