CULTIVATION AND COVER CROPPING
In its broad sense cultivation is the treatment of the soil. Thus
understood orchard cultivation includes the sod mulch system as well
as the stirring of the soil with various implements. In its more
common and restricted meaning, however, cultivation is the stirring of
the soil about plants to encourage growth and productivity. To have
the apple tree in sod was once the commonly accepted method of orchard
treatment--a method of neglect and of "letting well enough alone."
With the advent of more scientific apple culture the stirring of the
soil has come to be the more popular method. But within the last few
years an improved modification of the old sod method, known as the sod
"mulch" system, has attracted much attention because of the success
with which a few men have practiced it. For a correct understanding of
these practices and of the relative desirability of these systems we
must again turn to underlying principles and purposes.
It may be said on first thought that tillage is a practice contrary to
nature. But it accomplishes what nature does in another way. Tillage
has been practiced on other crops than trees for so long that we think
of it almost as a custom. There are, however, scientific and practical
reasons for tillage.
THE EFFECTS OF TILLAGE on the soil are three fold, physical, chemical,
and increasing of water holding capacity. Tillage affects the soil
physically by fining and deepening it, thus increasing the feeding
area of roots, and by bringing about the more free admission of air
warms and dries the soil, thus reducing extremes of temperature and
moisture. Chemical activities are augmented by tillage in setting free
plant food, promoting nutrification, hastening the decomposition of
organic matter, and the extending of these agencies to greater depth.
Tillage conserves moisture by increasing the water holding capacity of
the soil and by checking evaporation.
Of all these things which tillage accomplishes in a soil, two should
be especially emphasized for the apple orchard, namely, soil moisture
and soil texture. That moisture is a very important consideration in
the apple orchard the effects of our frequent droughts are ample
evidence. The amount of rainfall in the Eastern States when it is
properly distributed is fully sufficient for the needs of an apple
tree. By enlarging the reservoir or water holding capacity of the soil
and by preventing the loss of water by evaporation, an excess of
rainfall in the spring may be held for later distribution and use.
As a rule, the improvement of a poor soil texture is as effective as
the supplying of plant food and much cheaper. The latter is of no
consequence unless the plant can use it. Scientists tell us that there
is an abundance of plant food in most soils. The problem is to make it
available. Plant food must be in solution and in the form of a film
moisture surrounding the smallest soil particles in order to be
available to the fine plant rootlets which seek it. Good tillage
supplies these conditions. Can they be obtained equally well in
another way?
It is claimed by the advocates of the sod mulch system of orchard
culture that it also supplies these conditions. Humus or decayed
vegetable matter holds moisture. Grass or other mulch decaying in the
soil increases its humus content and hence its water holding capacity.
By forming a mulch over the soil evaporation may be checked to some
extent, although probably not as effectively in a practical way, as by
cultivation. If there is a good grass sod in the orchard, moisture and
plant food made available by that moisture are utilized, and if the
grass is allowed to go back into the soil it continues to furnish
these elements to the tree. But there is a rapid evaporation of
moisture from the surface of the leaves of grass. In fact, grass may
well serve to remove an excess of moisture in wet seasons, or from wet
lands.
Laying aside theoretical considerations, let us see what practical
experience teaches on this subject. We have the accurate data on a
large number of western New York orchards showing the results of
cultivation and other methods of soil management. These data are
overwhelmingly in the favor of cultivation. In Wayne County the
average yield of orchards tilled for five years or more was 271
bushels per acre, as compared with 200 bushels per acre for those in
sod five years or more but otherwise well cared for,--an increase of
thirty-five per cent. in favor of good tillage. In Orleans County,
under the same conditions, the increase in yield due to cultivation
was forty-five per cent. and in Niagara County it was twenty-two per
cent. Records were made on hundreds of orchards and the results should
be given great weight in determining the system to be practiced, as
intelligent consideration of trustworthy records is to be encouraged.
These results were obtained in one region under its conditions and it
is quite possible, although not probable, that other conditions might
give different results. There are, however, special conditions as will
be pointed out later, under which the sod mulch method might be more
advisable than tillage. It is cheaper, makes a cleaner cover for the
drop fruit, avoids the damage from tillage implements to which tilled
trees are liable, and can be practiced on lands too steep to till. It
often happens, too, that it fits into the scheme of management on a
general farm better than the more intensive and specialized system of
cultivation. And it must be remembered that we are dealing with this
question from the point of view of the home farm rather than of the
commercial orchardist. So that where the sod mulch gives equally good
results it would be preferred under these conditions.
LATE FALL AND EARLY SPRING PLOWING.--The common tillage practice in
the sections where it is most followed is to plow either in late fall
or as early as possible in the spring. Whether fall or spring plowing
is best depends on two things: the character of the soil and
convenience. On heavy clay soils where drainage is poor it is not
advisable to plow in the fall as the soil is apt to puddle and then to
bake when it dries, making it hard to handle. On gravel loams, medium
loams, and all well drained soils which are fairly open in texture
either fall or spring plowing is practiced depending on which period
affords the most time.
On the general farm where there are several crops for which the land
must be prepared in spring, it would seem best to get as much of the
plowing as possible done in the fall. But a large crop of apples or a
large and late corn husking or potato digging may interfere with this
on some farms and make spring plowing more desirable. Always plan this
work in connection with the other farm work so as to give the best
distribution of labor.
After fall plowing either the spring-tooth harrow or the disk harrow
is best to use to work up the soil and no time should be lost in
getting at this as soon as the land is dry enough in the spring.
Sometimes the disk harrow can be used to work up the soil in the
orchard in the spring without any plowing at all, especially on loose
loams where there are few stones. But on newly plowed land a disk cuts
too deep and there is too great danger of injuring the roots. On
spring plowed land the spring-tooth harrow usually gives the best
results. After the soil is thoroughly fined and worked into a mellow
bed and as soon as the period of excessive moisture in spring is
passed, a lighter implement like the smoothing harrow or a light
shallow digging cultivator should be used to stir the surface of the
soil only.
The growing period for an apple tree begins as early as growth starts
in the spring and continues up to about midsummer. If cultivation is
to stimulate growth as much as possible, it should be done during this
period. The first object of cultivation in the early spring is to
loosen up, aerate, and dry out the soil, which is usually too wet at
that time. As cultivation is continued the soil will become fined and
firmed again by the time drier weather comes on. A fairly deep
digging and lump crushing tool is the best implement to use up to this
time, and a disk or spring-tooth harrow meets these requirements.
After this period is passed and during drier weather, cultivation is
carried on for a different purpose, namely, to conserve moisture by
making a thin dust mulch of soil over the surface. This is best
accomplished by shallow-going implements of which the spike-tooth
harrow, the acme harrow, or a light wheel cultivator are best. As the
season and the amount of rainfall vary, so must tillage operations be
varied. In an early dry season begin with the lighter implements
earlier. In a late wet season keep the digging tools at work later. As
soon as the soil is in good physical condition the principal object of
tillage is to modify moisture conditions.
As a matter of practice three to four harrowings at intervals of a
week to ten days are necessary. Sometimes more, sometimes less are
required, according to the character and condition of the soil and the
season. The later moisture-conserving tillage should also be carried
on every week or ten days, according to weather conditions. It is good
practice to stir the soil after every heavy or moderately heavy rain.
Use the smoothing tools after light to medium rains and the heavier
tools after packing or beating rains. In practice from five to eight
or ten of these cultivations are necessary. The drier the season the
more necessary does frequent cultivation become.
A COVER CROP is so closely associated with tillage that it is usually
considered a part of the system. It should be sown in midsummer as soon
as tillage ceases. This time will vary from July first to August
fifteenth, depending on the locality, the rainfall, the crop of fruit
on the trees, and on how favorable the conditions for securing a good
stand of the cover crop are. The farther south the locality, or the
earlier the fruit, the sooner the crop should be sown. Absence of
sufficient rainfall necessitates a continuation of the cultivation,
both because it is necessary to conserve all the moisture possible and
because it is difficult to get a good stand of a cover crop--especially
of one having small seeds--at a dry time in midsummer.
In a year when there is a full crop of fruit on the trees cultivation
should be continued as late as possible as all the stimulus that can
thus be secured will be necessary to help the fruit attain good size
and maturity, and at the same time enable the tree properly to mature
its fruit and leaf buds for the following year. On the other hand, in
a year when there is not a full crop of fruit cultivation should be
stopped early so as to avoid forcing a too rank growth of wood and
foliage and continuing the growth of the next season's buds so late
that they may not mature and therefore may be in danger of winter
killing.
The different kinds of cover crops which may be used in the apple
orchard will be considered in the next chapter as they are so closely
associated with fertilization. Strictly speaking, however, a cover
crop is used principally to secure its mulching and physical effects
on the soil in the intervals between the seasons of tillage. In
addition to its physical and feeding effects the cover crop serves to
check the growth of trees in the latter part of the season by taking
up the nitrates and a part of the moisture, thus helping to ripen the
wood.
SOD MULCH.--The ordinary sod culture which is practiced in so many
orchards should not be confused with the sod mulch system. The one is
a system of neglect, the other of intention. In the sod mulch system
the grass sod is stimulated and encouraged and when the grass dies or
is cut, it is left on the ground to decay, forming a soil mulch
meanwhile. The removal of grass from the orchard as hay is poor
practice and should be discouraged. The grass mulch may well be
supplemented by the addition of other grass, straw, leaves, coarse
manure, or other similar materials. Sometimes this mulch is put on to
the depth of six inches or even a foot around the tree. Thus practiced
it is very effective in conserving moisture and in adding the humus
which is so necessary to the soil.
Sod and tillage have somewhat different effects on the tree and on the
fruit. Let us see what these effects are. It is common knowledge that
fruit is more highly colored when grown in sod than when grown under a
tillage system. This is probably largely due to the fact that tillage
keeps the fruit growing so late that it does not mature so well or so
early. Fruit is usually two or three weeks later in tilled than in sod
orchards. It has been shown that fruit grown under tillage keeps from
two to four weeks longer than that grown in sod. It is claimed
also--but this is a disputed point--that tilled fruit has a better
quality and flavor. Certain it is that fruit grown in sod is drier
and less crisp and juicy.
The effect of tillage on the trees is more marked and better known.
Tilled trees have a darker, richer green foliage, indicating a better
and more vigorous health. The leaves are also larger and more
numerous. They come out three or four days earlier in the spring and
stay on the trees two weeks later in the fall than the leaves on trees
kept in sod. Tilled trees make nearly twice the growth in a season
that those in sod do, in fact there is danger of their making wood
growth at the expense of fruit buds. Tillage also gives a deeper,
better distributed root system.
Despite the advantages and the disadvantages of each system, there are
times, places, and circumstances under which one is more advisable
than the other. On lands rich in humus and in plant food and level so
as to be easily tillable, cultivation is without doubt the best
system. But it should be practiced in connection with cover crops, and
the orchard should be given occasional periods of rest in sod--say one
year in from three to five.
The sod mulch system of orchard culture is probably better adapted to
rather wet good grass land and where mulching material is cheap and
readily available. It is undoubtedly at its best on lands too steep or
rough to till, or otherwise unsuitable to cultivation. Tillage is the
more intensive method and where labor is scarce and high sod culture
might be more advisable for this reason, other conditions being not
too unfavorable.
In order to illustrate a method of management under the tillage system
we may suggest the following as a good one for level to gently rolling
land:
1912. Early plowing in spring, cultivation to July first to
fifteenth. Then sow red clover as a cover crop.
1913. Repeat previous year's treatment, varying the time of
sowing cover crop according to conditions.
1914. Let the clover grow, mowing and leaving on the ground as a
mulch, June fifteenth to twentieth, and again in August.
1915. Plow early in spring, cultivate to midsummer, and then sow
rye or buckwheat as a cover crop July fifteenth to August
fifteenth.
1916. Repeat 1915 treatment and if trees are not growing too
fast, sow clover or hairy vetch as a cover crop.
1917. Same as 1912, etc.
PASTURING THE ORCHARD.--The sod mulch system explains itself and does
not need illustration. Sod orchards are often managed as pasture for
animals, however, and this practice should be discussed. An orchard is
considered as pastured when a considerable number of animals are
turned into it for a greater or less portion of the year. Results in
orchards where pasturage has been thoroughly tried out show that it is
never advisable to pasture an orchard with horses or cattle, but that
fairly good results may be expected where sheep or hogs are used.
The evidence of yield of fruit and appearance of trees both indicate,
that pasturing an orchard with horses or cattle is about the worst
possible practice. These animals rub against the trees, break the
branches, browse the limbs and leaves, and destroy the fruit as high
as they can reach. All experience is against this practice which
cannot be too strongly deprecated.
Pasturing an orchard with sheep, although a somewhat doubtful
practice, often gives good results. Sheep crop the grass close to the
ground and to some extent prevent the extensive evaporation which
usually takes place from the leaves of grass. Their well distributed
manure is worth considerable. They also browse the branches to some
extent and should not be allowed to run in the orchard late in the
season as they will destroy considerable fruit.
Pasturing an orchard with swine gives better results than any other
pasture treatment of the orchard. Hogs do considerable rooting which
prevents the formation of a stiff sod and itself may often amount
almost to cultivation in well stocked orchards. A good deal of manure
is added to the soil, especially when the hogs are fed outside the
orchard. Hogs also destroy many insects by eating the wormy fruit.
Pasturage of orchards has its advantages. It gives a double
utilization of the land. It is a cheap method of management. When the
animals are fed outside the orchard, as should always be the case, it
adds considerable plant food to the soil. When plenty of outside food
can be given and when the orchard is not overstocked--the animals
should never be hungry--hogs and sheep may be used to advantage in
pasturing orchards. In very rough fields incapable of tillage, this is
undoubtedly the very best system of orchard management.
Pasturage has the disadvantage of exposing young trees to injury from
the animals, but this may be at least partly avoided by protecting
them with stakes or a heavy wire meshed screen. Hogs especially soil
the fruit and make the land rough and difficult to drive over. Under
the proper conditions pasturage may be practiced to advantage,
especially on small areas and on the general farm where it is more
advantageous than it would be commercially.