« ՆախորդըՇարունակել »
the second year. The third year the ground was put in summer grain which completed the shift. Then the farmer began again with a year of fallow and manure, a year of winter grain, a year of summer grain; and so he went on-three years—three years—three years—indefinitely. I suppose there are districts in Europe that could be pointed out where this practice has prevailed for nearly a thousand years, and it was early imported into this country. It was the subject of legislation in the time of Charlemagne.
Some historians think that this monarch decreed the adoption of the three years shift; others think that he merely recommended it, as an improvement on what had been previously the custom among the less advanced peasants, of simply using the plow for a succession of years, without any rest for the land. In the vicinity of cities, where the plowed land increased in proportion to the quantity of pasture, and the supply of dung became inadequate to manure it sufficiently, so that the manure and fallow together could not make two good grain crops, forage plants--grass, clover, or roots-were introduced into the course; and in that way, a great variety of rotations came into use.
In England, there has been practiced, over a considerable part of the country, what is known as the Norfolk rotation"-a four years
You have all read of it, doubtless; The first year, clover and mixed grass seed; the second year, wheat; the third year, turnips or rutabagas; the fourth year barley; and then the same course again, with, perhaps a little variation; perhaps the land was kept two years in clover and grass. In Dorset, Wilts, Essex, Herts, Suffolk, and Cambridge, in England, ten or fifteen years ago, this course was in almost universal use. I speak of this matter to bring up one point. There are certain advantages in rotation which being observed or conceived led to its adoption. But farmers, especially in long-settled countries like England, are apt, having once accustomed themselves to a routine, to adhere to it long after its advantages cease to exist. This is illustrated by the fact that Norfolk, which gave England the four-course system just described, began more than thirty years ago to amend its own improvements. The command of concentrated and artificial fertilizers which admit of easy application at any point in a rotation, led some of the best farmers there to introduce another grain crop-oats-into the shift, making a five years course, and according to Caird, in his “ English Agriculture," "on a large farm where this system has supplanted the four years course the
average produce of all the grain crops has increased in ten years between thirty and forty per cent.; the extent of land on this farm in wheat, having during that period annually increased till it has now (1850–51) become one-third greater than it was then.”
In Great Britain, Germany, and other European countries, you will find in many localities very complicated systems of rotation. I saw the other day, in a book which I was looking into for some statistics, a long and curious calculation, showing the various materials-lime, potash, phosphoric acid, &c.--taken off and put on a farm, which was divided into ten equal fields, and each of these fields, went through successively with the same ten years' rotation; which was : 1, Summer Fallow, manured. 2, Winter Coleseed. 3, Wheat and Rye. 4, Legumes, manured. 5, Rye. 6, Potatoes. 7, Clover and grass. 8, Clover hay. 9, Pasture till 1st July, then summer fallow. 10, Rye and Wheat, “half manured."
It is a great advantage, in the conduct of a large estate of four or five hundred acres, to have the whole system of cropping made up beforehand, so that the men can tell just what is to be done from year to year. The management of farm labor is simplified by this arrangement. That is one of the reasons why such complicated rotations are adopted.
It should be well borne in mind that while there are circumstances in which rotation is extremely advantageous there are other circumstances under which it is comparatively unimportant. Certain conditions make rotation necessary, and others make it unnecessary. There are two kinds of agriculture, which have been defined as extensive" and "intensive." The “extensive" is where land is cheap, and where capital, labor and manure are scarce. There the farmer must go over a great deal of surface, and depend chiefly upon the natural resources of his farm,-getting out of it what he can, " by hook or by crook.” “Intensive" agriculture is where the circumstances are such that the farmer uses a comparatively small quantity of land and a large amount of capital, is able to get fertilizers in abundance, and sells his cróp quickly and at a good price. He puts a great deal more into the soil and gets a great deal more from it than his “extensive" brother. He works in a more intense way. That is, his labor, instead of being spread over two hundred acres, is concentrated on fifty, and he is able to make his fifty acres more profitable than the other farmer can make his two hundred. In "extensive"
agriculture we usually have a large quantity of pasture and keep a good many cattle, for we have to depend largely on their manure. We have to sell off a large share of the crops, which remove valuable materials from the soil, and we cannot or do not buy fertilizers to make good the deficiency. In the other case, the farmer can put in as many fertilizers as he chooses to pay for. He is able to buy them, and he finds his profit in using them. In "extensive" agriculture, which is made necessary by circumstances, the farmer must depend largely upon rotation; he must bring it into successful use.
As he succeeds or fails to do this he carries on a paying or a losing business. In "intensive” agriculture the farmer is largely independent of this necessity; he can rotate or not, very much as he chooses. Rotation is not indispensable to his success. That is, the advantages that come from rotation are not so great as the other advantages which the farmer has at command by the use of plenty of money, plenty of fertilizers, by his nearness to market, and.bigh prices.
Now, I wish to state some of those principles which should govern us in rotation, so far as this depends on what we may call the chemistry of the crop and the soil. So far as the feeding power of the soil is concerned, the special requirements of the crop should determine the rotation. Of course there are other conditions to be taken into account in practice. Winter wheat, for example, cannot follow itself beyond a certain length of time, even if the soil will allow, because the land ordinarily becomes foul with weeds; and it is better to alternate with some crop which will enable us to destroy the weeds by hoeing or which will choke them out directly. There are many conditions which influence rotation that I do not propose to speak of, but I shall confine myself to that part of the subject which is involved in the feeding of the plant. The broadest principle of rotation is to alternate grain crops and forage crops. That is, to follow plants having a short and rapid growth and which produce seed, by plants of a longer period of growth which are not allowed to ripen seed, but are harvested for their large amount of foliage.
Plants, like animals, have different ways of feeding. If you were to undertake to keep a dairy of hyenas you would have to provide a different food from that which you give to cows. If you should choose the giraffe as a domestic animal you would find that its babits of feeding are adapted to very different circumstances from those of your common pastures. The natural food
of the giraffe is mainly the buds and twigs of a kind of locust tree that grows in the African wilderness, and the long fore-legs and long neck of the animal are shaped for browsing among the tops of those trees. The different classes of plants have peculiarities in their feeding arrangements which are as marked and striking as these differences in animals.
On comparing together the roots of our ordinary crops, we find that when they grow under similar circumstances there is a great difference in the depth to which they extend, a great difference in the degree in which they branch, and a great difference in the absolute quantity of roots. Unfortunately, we have not enough really satisfactory observations on these points to serve us in any very extended comparison, it being rather troublesome to make accurate observations of the roots of plants when they have once penetrated the soil. A few brief paragraphs in my book “How Crops Grow,” embrace pretty nearly all we know about this matter of the growth of roots. As to depth, Schubart has made the most satisfactory observations we possess on the roots of several important crops growing in the field. He separated them from the soil by the following expedient: an excavation was made in the field to the depth of six feet, and a stream of water was directed against the vertical wall until it was washed away, so that the roots of the plants growing in it were laid bare. The roots thus exposed in a field of rye, in one of beans, and in a bed of garden peas presented the appearance of a mat or felt of white fibers to a depth of about four feet from the surface of the ground. Roots of winter wheat were observed as deep as feet in a light sub soil, forty-seven days after sowing. The depth of the roots of winter wheat, winter rye, and winter coleseed, as well as of clover, was three to four feet.” Schubart further collected and weighed the roots of wheat, rye, and peas, and ascertained their proportion of the entire plant Hellriegel has also published some observations on the extent of the roots of barley and oats.
We have a few other observations of this sort, but not enough to enable us to determine the comparative quantity and depth of the roots of our cultivated plants with any accuracy.
It will not do to draw conclusions as to the length of roots from such observations as these, made, it would appear, in different soils, differently treated and fertilized, because other observations show that the development of the root depends not exclusively upon
any impulse which it receives from the plant (that is, the root must not necessarily weigh so much or measure so much), but depends also upon the nature of the soil. Where this is rich the roots tend to remain ; they branch and ramify through all the pores of a small bulk of earth. Where this is poor they stretch off' and are sparsely distributed through a larger space. Where they find plenty of food they grow and multiply upon it; where nourishment is lacking they seem to go in search of it. All observations must therefore be comparative. We know, however, in a general way, that the development of roots is different in different classes of plants. We know that clover has a much deeper system of roots than our ordinary grains. We know that where the soil is rich at the surface, and where it is adapted naturally, by its mechanical condition to the growth of wheat, for example, the large proportion of wheat roots are found within a rather narrow space. On the fertile plains surrounding the town of Leipzig, the principal commercial city of Saxony, situated in one of the richest agricultural regions of Germany, I have seen the same kind of plow going back and forth, which you will find pictured in the classical dictionaries as used by the Romans. If you should take a shingle five inches wide and sharpen it to a blunt point, you would have about the shape of the plowshare I refer to.
This wooden instrument, shod with thin iron, did not turn a furrow; it simply made a groove about four inches deep from crest to base, stirring and mixing the soil thoroughly, however, to that extent. This was the only kind of plowing I saw practised on these fields in 1854, and yet splendid crops were harvested from them. The soil was doubtless naturally of excellent texture and allowed a due penetration of the roots. But the fact remains that with such tillage all fertilizing applications must remain near the surface, and this makes evident that the roots of our grains need not go down to any very great depth. If the soil has nourishment and moisture for them, six or eight inches of earth will answer for the support of a crop. A foot will, in a majority of cases where the soil is of good quality, contain the bulk of the roots of the wheat crop. They may go deeper, as Schubart observed, but only because they must descend in order to find food or drink. It has been shown by experiment that roots develop in poor spil in the vicinity of any enriching material ; so that we cannot say, because Indian-corn roots have been traced for twenty