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, gra.s.s, 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.

GENERAL RULES

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 gra.s.s 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.

CHAPTER XXV

FARM DRAINAGE

Some farm lands contain so much water that the conditions of fertility are interfered with and therefore the crop producing power of these lands is lowered.

HOW SURPLUS WATER AFFECTS FERTILITY

This surplus water diminishes fertility by reducing the area of film water in the soil.

It checks soil ventilation.

It tends to keep the soil cold.

It dilutes plant food in the soil.

It interferes with proper tillage.

INDICATIONS OF A NEED OF DRAINAGE

The above-mentioned state of affairs occurs sometimes in fields at the foot of hills, or on sloping uplands which receive spring water or seepage water from higher lands. Some fields are underlaid by a close, compact subsoil which so checks percolation that the surface soil is too wet for tillage operations the greater part of the year. In such cases:

A need of drainage is generally indicated by the presence of more or less free water standing on the surface.

In some lands the surface water does not appear as free water standing on the surface. In such cases:

A need of drainage is indicated by the curling and wilting of the leaves of corn and other crops during dry, hot weather. This curling and wilting is due to the fact that during the early growth of the crop free water stands so high in the soil that the crop roots are confined to a shallow layer of soil. When dry, hot weather comes, the free water recedes, the upper soil dries out, and the roots cannot get sufficient water to supply the demands of transpiration, hence the curling and wilting of the leaves.

If drains are placed in this soil, the free water will be kept at a lower level in the spring and the plant roots will develop deeper in the soil, where there will be constant supply of film water during the dryer and warmer summer weather.

The wiry and spindling growth of gra.s.s and grain crops may indicate too much water.

The growth of moss on the surface of the ground and the cracking of the soil in dry weather are also indications of too much water.

DRAINS

How can we get rid of this surplus free water?

We can make pa.s.sageways through the soil to a lower level and then let gravity pull the water through them to lower ground below. These pa.s.sageways are called drains.

Drains may be cla.s.sed as:

Surface drains which are shallow, open channels made in the soil with a plow, hoe or other tool, to carry off surface water. They are temporary and need frequent renewing.

Open-ditch drains are deeper, more permanent water pa.s.sageways around or across the fields.

Surface and open-ditch drains take only surface water. They also carry off surface soil and manures washed into them. They frequently become choked or stopped by trash and soil, and are in the way of cultivation and harvesting operations.

Covered drains, under drains or blind ditches are water pa.s.sageways made of brush, poles, stones, tiles, etc. (Figs. 80-81), placed in the bottoms of ditches and then covered with soil.

INFLUENCE OF COVERED OR UNDER DRAINS ON FERTILITY

_Influence on soil water._

Covered or under drains take not only surface water, but also remove free water from the soil beneath down to nearly the level of the bottom of the drains, and thus increase the area of film water.