"The above is the mode of cultivation which has been generally pursued here, but the system of husbandry which has been found so beneficial in England, and which must be greatly promoted by your valuable Annals, is now gaining ground. There are several (among which I may class myself), who are endeavouring to get into your regular and systematic course of cropping, as fast as the nature of the business will admit ; so that I hope in the course of a few years, we shall make a more respectable figure as farmers than we have hitherto done." Fallowing.
A significant part of Washington's letter is the statement that land was "respited " for eighteen months. He meant that the land was allowed to lie idle or fallow. It is an old notion that land "rests" when allowed to go wholly uncropped ; and, in fact, it is true that the succeeding crops may be better for the fallow, but in most instances equally good results can be secured by other means and without the loss of a year's crop. The fallow was a regular part of early rotation practices. Fallowing was employed by the Jews, Greeks and Romans. It is common in many large parts of Russia and other countries to-day.
In special cases and in regions of insufficient rainfall, fallowing is still an allowable practice ; but in genera] it belongs to a rude and unresourceful type of agriculture. In most of the humid regions of this country the practice, if employed at all, is diminished to "summer fallowing," whereby the period of idleness is reduced to a minimum. The summer fallow was formerly often employed in order to fit the land for wheat. The land was kept in more or less clean and free tillage from spring till fall, without crop, for the purpose of destroying weeds and of putting it in good condition of preparation. With improved tillage implements and well-planned rota tions, these special results usually can be secured without resort to fallow.
Why rotations are useful.
There is no dispute as to the value of rotation of crops. The only differences of opinion are in respect to its feasibility in particular cases and the merits and demerits of the different courses. Many experi ments have reenforced common experience as to the importance of rotation, particularly in recuperating old lands. Experiments made at Rothamsted are perhaps the most conclusive, because of the long period. Wheat has been grown without rotation for sixty-six years and other crops for varying periods. No method of fertilizing potatoes or clover kept up the yield without rotation. Rotation alone did not fully
maintain the yield of any crop, but the combination of manure or fertilizers with rotation increased it. At the Louisiana Experi ment Station (to cite only one more illustration), it was found, as a result of eleven years' work with a three-course rotation (first year corn, second year oats followed by cowpeas, third year cot ton), that the yield in creased from 12 to 25 per cent even without the application of ma nure. In another part of the same experiment, ma nure was applied and the general increase in yield was 400 to 500 per cent. This shows that a plain rotation is itself capable of increasing yield, but that a greater increase is to be expected by a combination of rotation and manuring.
The first rotation-farming to gain wide attention in North America seems to have been the so-called Norfolk system. This was chiefly a four-crop rotation employed on the light lands of Norfolk, England, and which had grown up during a long course of years. A century and more ago this system was explained by writers and thereby became widely known, the more so because at that time the American agricultural literature was drawn chiefly from English sources. An account of " the Improvements made in the County of Norfolk" comprised the larger part of Jared Eliot's "Fourth Essay upon Field Husbandry," published at Killingworth, Connecticut, in 1753. The exact rotation itself—comprising roots, barley, clover, wheat, in various combinat1ms—was of less impor tance to the American colonies than the fact that attention was called to the value of rotation-farming in general. At the same epoch another system of farming practice was also coming in from English sources. This was the clean tillage system introduced by the epoch-making experiments of Jethro Tull.
Between the discussions of the Tull " new husbandry" and the Norfolk rotations, agricultural practices were challenged and overhauled in the new country.
One of the early explanations of the good results of rotation of crops was the doctrine that some plants exhaust the soil of certain materials which are not needed by other plants ; therefore the value of rotation depended on securing such a combination of crops as would in time utilize all the elements of the soil. There is, of course, some truth in this teaching, but we now know that the question is by no means one of so-called exhaustion alone.