Atlanta tri-weekly journal. [volume] (Atlanta, Ga.) 1920-19??, 1921-11-12

button over the land. This means a
net loss Of over twelve dollars worth
of plant food when the stalks, leaves,
ct cetera, from a one-bale cotton
crop or a hundred-bushel corn crop,
are burned. Perhaps the organic
matter lost would have been equally
as valuable to the land as the plant
| food contained in the residues. The
total loss, then, when the farmer
burns these materials, is about $25.
Probably no other single factor has
done so much to cause the soils of
the Piedmont section to become run
down or worn out" as this practice
of burning off all litter in the spring.
| Certainly the loss suffered when
| these residues are burned makes 1t
/ worth while to go to the necessary
expense and trouble to get them in
condition for blowing under.
The function of nitrogen is to pro-
duce growth in the plant itself, Civ
| ing size to stalk and limb and deep
green color to the foliage. The need
| of nitrogen can be detected from
the crop itself through the absence
| of a deep green color and by weak,
stunted plants lacking in vigor.
After nitrogen and organic mat
| needs to be increased in the aver
age soils of the county is phosphor-
| ic acid. Where soils contain large
amounts of iron and small amounts
| of lime, as do most of the soils Of
| the Piedmont section Of the state,
| the phosphoric acid is believed to
! be largely combined with iron and
aluminium. The presence Of a fair
| ly large amount is, therefore, not an
| infallibIe indication that phosphoric
acid is not needed.
The need for available phosphoric
acid has been generally recognized,
but the practice does not generally
| take into account the different soil
| types on which the fertilizer is to
be used. The availability of the
phosphoric acid is largely depend
cnt upon the content of organic mat
ter and the general physical cOndi-
ton of the soil, so that even high
| content of this element may be of
little value when the land is allow
| ed to get in a rundown condition
| from continued clean cultivation.
In fertilizers used directly under
crops to meet Immediate needs, phOs-
phoric acid should be applied in the
form of acid phosphate or other
available form. However, in a
scheme of permanent agriculture
where soil building is an object,
rock phosphate affords the cheapest
source Of phosphorus. Phosphoric
acid can be bought in this form for
about one cent per pound, whereas,
it costs several times as much in
the form of acid phosphate. How
ever, the soil must be we'll stocked
with humus in order to get good re-
suits from rock phosphate; for it is
only in the presence of decaying or
gar1ic matter that this material will
give up its phosphorus. In connec-
ton with green manureS or with
heavy applications of farm manure,
rock phosphate should give good re-
suits. 1t should be applied broad
cast at the rate Of 1000 to 1000
pounds per acre about every five
years. This should be supplemented
with small amounts of acid phos-
phate, if needed, but the amount of
the expensive form required will be
greatly reduced and a net saving
made. 1t is well to remember, how
ever, that rock phosphate, of what
ever brand or source, cannot take
the place of acid phosphate in mixed
fertilizers. and farmers should not
buy it for this purpose.
Phosphoric acid performs a spe-
cial function in the fruiting of
plants, and hastens maturity. Poor
fruitage and late maturity in crops
are indications of the need of phos
phorus.
While there is a wide variation in
the amount of potash in the soils of
TO-,
of a few types they 'are we'll to
abundantly supplied with this con-
stituent. Some of the types are I'M
usually high in the amount of pot
ash they contain, and in this re-
spect are not typical Of the types
they represent.
Owing to the form in which it
occurs in the soil, however, potash
becomes available more slowly than
any other plant food. This is par
ticuIarly true of the sandy soils, as
the potash is here locked up in a
very insoluble form. Also the COM
paratively large size of the sand
grains, as compared with the finer
| material, presents a very much less
total surface to the action of sol
vents in the soil. For these reasons,
potash usually pays on the sandy
lands, notwithstanding the fact that
| they contain more potash than the
clay lands in many cases.
Like phosphorus, the availability
Of the soil potash is largely depend
ent upon the physical condition of
the soil. An abundance of organic
| matter, combined with deep tillage
and thorough cultivation, would in
sure enough available potash to meet
the requirements of ordinary field
crops in most cases.
Potash aids in the formation of
the starch and woody material of
plants, giving sturdiness of stalk
and well developed branches. It is
an especially important fertilizer
constituent for all fruit and truck
! crops. 1t accumulates chiefly in the
leaves and stems of plants, and is
largely returned to the soil where
plant residues are not removed, and
| thus affords a source of available
| potash for the succeeding crop.
| Weak, spindling plants with rust
| ing leaves indicate a need of potash.
C+p1II N@IE1