Agriculture for Beginners | Page 9

should not allow
anything to be lost from our farms. All the manures, straw, roots,
stubble, healthy vines--in fact everything decomposable--should be
plowed under or used as a top-dressing. Especial care should be taken
in storing manure. It should be watchfully protected from sun and rain.
If a farmer has no shed under which to keep his manure, he should
scatter it on his fields as fast as it is made.
[Illustration: FIG. 15. THE COTTON PLANT WITH AND WITHOUT
FOOD In left top pot, no plant food; in left bottom pot, plant food
scanty; in both right pots, all elements of plant food present]
He should understand also that liquid manure is of more value than
solid, because that important plant food, nitrogen, is found almost
wholly in the liquid portion. Some of the phosphoric acid and
considerable amounts of the potash are also found in the liquid manure.
Hence economy requires that none of this escape either by leakage or
by fermentation. Sometimes one can detect the smell of ammonia in the
stable. This ammonia is formed by the decomposition of the liquid
manure, and its loss should be checked by sprinkling some floats, acid
phosphate, or muck over the stable floor.
Many farmers find it desirable to buy fertilizers to use with the manure
made on the farm. In this case it is helpful to understand the
composition, source, and availability of the various substances
composing commercial fertilizers. The three most valuable things in
commercial fertilizers are nitrogen, potash, and phosphoric acid.
The nitrogen is obtained from (1) nitrate of soda mined in Chile, (2)
ammonium sulphate, a by-product of the gas works, (3) dried blood and
other by-products of the slaughter-houses, and (4) cotton-seed meal.
Nitrate of soda is soluble in water and may therefore be washed away
before being used by plants. For this reason it should be applied in
small quantities and at intervals of a few weeks.
Potash is obtained in Germany, where it is found in several forms. It is

put on the market as muriate of potash, sulphate of potash, kainite,
which contains salt as an impurity, and in other impure forms. Potash is
found also in unleached wood ashes.
Phosphoric acid is found in various rocks of Tennessee, Florida, and
South Carolina, and also to a large extent in bones. The rocks or bones
are usually treated with sulphuric acid. This treatment changes the
phosphoric acid into a form ready for plant use.
These three kinds of plant food are ordinarily all that we need to supply.
In some cases, however, lime has to be added. Besides being a plant
food itself, lime helps most soils by improving the structure of the
grains; by sweetening the soil, thereby aiding the little living germs
called bacteria; by hastening the decay of organic matter; and by
setting free the potash that is locked up in the soil.
CHAPTER II
THE SOIL AND THE PLANT
SECTION VIII. ROOTS
[Illustration: FIG. 16. ROOT-HAIRS ON A RADISH]
You have perhaps observed the regularity of arrangement in the twigs
and branches of trees. Now pull up the roots of a plant, as, for example,
sheep sorrel, Jimson weed, or some other plant. Note the branching of
the roots. In these there is no such regularity as is seen in the twig.
Trace the rootlets to their finest tips. How small, slender, and delicate
they are! Still we do not see the finest of them, for in taking the plant
from the ground we tore the most delicate away. In order to see the real
construction of a root we must grow one so that we may examine it
uninjured. To do this, sprout some oats in a germinator or in any box in
which one glass side has been arranged and allow the oats to grow till
they are two or more inches high. Now examine the roots and you will
see very fine hairs, similar to those shown in the accompanying figure,
forming a fuzz over the surface of the roots near the tips. This fuzz is
made of small hairs standing so close together that there are often as

many as 38,200 on a single square inch. Fig. 17 shows how a root looks
when it has been cut crosswise into what is known as a cross section.
The figure is much increased in size. You can see how the root-hairs
extend from the root in every direction. Fig. 18 shows a single root-hair
very greatly enlarged, with particles of sand sticking to it.
[Illustration: FIG. 17. A SLICE OF A ROOT Highly magnified]
These hairs are the feeding-organs of the roots, and they are formed
only near the tips of the finest roots. You see that the large, coarse roots
that you are familiar with