Rotation of crops economizes the natural plant food of the soil and also that which is applied in the form of manure and fertilizer. This is because:
Crops take food from the soil in different amounts and different proportions.
Crops differ in their feeding powers.
Crops differ in the extent and depth to which they send their roots into the soil in search of food and water.
Crops differ in the time of year at which they make their best growths.
Rotation helps to maintain or improve the texture of the soil because the amount of humus in the soil is maintained or increased by turning under green manure and cover crops which should occur in every well-planned rotation.
Rotation helps to maintain or increase the plant food in the surface soil. When crops like cowpeas or clover which take mineral food from the subsoil and nitrogen from the air, are plowed under, they give up the plant food in their leaves, stems and upper roots to the surface soil, and thus help to maintain or increase fertility.
Rotation tends to protect crops from injurious insects and diseases. If one kind of crop is grown continuously on one piece of land the soil becomes infested with the insects and diseases which injure that particular crop. If the crop is changed, the insects and diseases find difficulty in adapting themselves to the change and consequently diminish in numbers.
Rotation helps to keep the soil free from weeds. “If the same kind of crop were grown year after year on the same field, the weeds which grow most readily along with that crop would soon take possession of the soil.” For example, chick weed, dock, thistle, weeds peculiar to grain and grain crops tend to increase if the land is long occupied by these crops.
Rotation helps the farmer to make a more even distribution of labor throughout the year. This is because crops differ as to the time of year at which they are planted and harvested.
Rotation of crops enables the farmer to provide for his stock more economically. Live stock fares better on a variety of food, which is more cheaply secured by a system of rotation than otherwise.
THE TYPICAL ROTATION
A typical rotation for general farming should contain at least:
One money crop which is necessarily an exhaustive crop.
One manurial crop which is a soil enricher.
One feeding crop which diminishes fertility only a little.
One cleansing crop, a hoed or cultivated crop.
CONDITIONS WHICH MODIFY THE ROTATION
There are certain conditions which tend to modify the rotation or to influence the farmer in his choice of crops. They are as follows:
First of all the climate will set a limit on the number and varieties of crops from which a choice can be made for a given locality.
The kind of farming which he chooses to carry on, whether stock raising, grain farming, truck farming, or a combination of two or more of these, or others.
Kind of soil. Certain soils are best adapted to particular crops. For example, heavy soils are best suited to wheat, grass, clover, cabbages, etc. Light, sandy soils to early truck, certain grades of tobacco, etc.
The demand for crops and their market value.
Facilities for getting crops to market, good or bad country roads, railroads and water transportation.
The state of the land with respect to weeds, insect pests and plant diseases.
A few general rules may be made use of in arranging the order of the crops in the rotation though they cannot always be strictly followed.
Crops that require the elements of plant food in the same proportion should not follow each other.
Deep-rooted crops should alternate with shallow-rooted crops.
Humus makers should alternate with humus wasters.
Every well arranged rotation should have at least one crop grown for its manurial effect on the soil, as a crop of cowpeas, or one of clover, to be turned under.
The objection often made to this last rule is that, aside from the increase in fertility, there is no direct return for the time, labor and seed, and the land brings no crop for a year. It is not necessary to use the entire crop for green manuring—a part of it may be used for hay or for pasture with little loss of the manurial value of the crop, provided the manure from that part of the crop taken off is returned and the part of the crop not removed is turned under.
LENGTH OF THE ROTATION
The length of the rotation may vary from a two-course or two crop rotation to one of several courses. Crimson clover may be alternated with corn, both crops being grown within a year.
A three-course rotation, popular in some parts of the country, is wheat, clover, and potatoes; potatoes being the money crop and cleansing crop, wheat a secondary money crop or feeding crop, and clover the manurial and feeding crop.
A popular four-course rotation is corn, potatoes or truck, small grain, clover; the potatoes being the chief money crop, corn the feeding crop, the small grain the secondary money or feeding crop, and clover the manurial and feeding crop.
On many New England farms near towns, hay and straw are the chief money crops. Here the rotation is grass two or more years, then a cleansing crop and a grain crop. A Canadian rotation is wheat, hay, pasture, oats, peas. A rotation for the South might be corn, crimson clover, cotton, crimson clover; this rotation covering a period of two years. A South Carolina rotation is oats, peas, cotton, corn—a three-year rotation. It might be improved as follows: Oats, peas, crimson clover, cotton, crimson clover, corn.
This article was taken from,
The First Book of Farming
By CHARLES L. GOODRICH
Publication date: 1905