CHAPTER VIII.
CROP ROTATION.
In agriculture on a large scale the difficulty is how to arrange the farm business so as to make it pay. It is only of late that we are beginning to understand that agriculture is a business, and that to make it pay one must apply business principles. The best farmer is not necessarily the one who knows the most “Science,” but the one who is able to fit his science, his facts and his business in together.
The market value of special crops is so high that the grower can afford to provide the extra manure and other expensive materials to keep the land in good condition. This is the chief reason for the use of great quantities of stable manure in market-gardening, far greater quantities than are needed for mere food of the crops. So if you find that you are advised to use more manure on your small plot than some farmer you know uses on his big field, do not feel that you are being imposed upon. He could not afford to use so much and you cannot afford to use less. The farmer on a large scale has to let part of his low priced land rest in clover once in a while. You cannot afford to let any of your small area rest, so you must make up to the land by giving it plant food enough.
In these days machinery has made so many wonderful changes in the management of crops that the farmer who sticks to the old farming customs has no chance of making more than a living. When the country was new, it was the practice to farm one section until it was exhausted, and then to move to fresh soil. The farmer was saved the bother of cultivating, as virgin soil needed practically only to be planted to bring forth a good harvest. But conditions have changed and the virgin soil left today is not important in the farming possibilities. Therefore, we have had to look for other means of getting crops and making every inch of land do its share. We no longer allow land to lie fallow that it may rest and renew itself. We renew it by fertilizing and by rotation of crops. Crop rotation is very valuable because it is a saving of fertilizer and labor, and keeps the soil in good condition. This has been proved by experiments made without manure, depending entirely upon rotation for fertilizing, which gave excellent results.
There are probably a dozen or more good reasons for the value of crop rotation which have not yet been discovered and formulated, but the following are well known:
Some crops tend to correct the faults of others. It has been proved that the continuous growing of one crop injures the soil in some respect, and the crop falls off both in quantity and quality. Rotation tends to overcome this difficulty. Then, too, this rotation works out and evens up the inequalities of the soil, partly through the different treatment required by the different crops.
Different plants draw different portions of food from the soil and at different times. By rotation these heavy drafts on the plant food do not come at the same times, and the seasons get a chance to even up the inequalities.
Different plant food gets mixed into the soil, so that the roots can feed on it, by the decay of the parts left in the ground or which are plowed under. But the greatest benefit comes from the nitrogen compounds through growing plants, such as cowpeas, crimson clover, etc.; these “leguminous” plants have little knots or tubers on their roots with the mysterious power of gathering the free nitrogen out of the soil or air, and turning it back again to the soil in condition to be used by other plants. Now nitrogen is the hardest to keep and the most expensive of all the plant foods that the farmer has to buy, and to get this nitrogen is sometimes the only reason he has for buying chemical fertilizers.
This shows the importance of leguminous crops to the farm. They supply this nitrogen at almost no cost, or at a profit.
Some plants have more power than others to use the contents of the subsoil, and may draw less on the upper soil, and further, by their decay may add richness to the earth. Most legumes have this power to take nourishment from the subsoil.
Well-planned rotation helps to maintain the supply of decayed stuff in the soil, on which the plants feed. It also improves the soil’s texture. Moreover, it not only lessens the necessity for much chemical fertilizer, but it puts those fertilizers to better use. Where live stock is kept, crops should be raised to feed the stock to make manure.
Rotation is, also, a plan for cleaning the soil. Different weeds and insects grow after different crops and the succession or “rotation” as we call it, prevents any kind getting a secure hold.
It enables the farmer to meet the demands of the market, by continuous crops.