That which forms the food of man is always the principal object in the cultivation ; and, excepting rice, which only grows in warm climates, there is no food more universally used than that which is made from wheat. Rye, barley, oats, and pulse are only substitutes where wheat cannot be raised in sufficient quantities. Next to grain conies meat, chiefly beef, mutton, and pork, of which the consumption increases with the wealth of a nation and the advance of its agricul ture. Wheat and fat cattle are therefore primary objects with every good farmer ; and he who can raise most wheat and fatten most oxen or sheep or pigs will realise the greatest profit.
Many circumstances may indicate a deviation from the course which, as a general rule, is most advantageous. The facility of purchasing manure from neighbouring towns may allow of moro frequent crops of corn, and of nutritious roots which require much manure, such as potatoes, and which give no return to the land in the shape of dung. But we must lay down rules for those who are to rely on their own resources to recruit the land with manure, so that it may give the greatest produce without diminishing in fertility ; and this can only be done by a judicious feeding of livestock.
The simple rotation of wheat and beans alternately would be by far the most profitable in rich clay soil, as both these crops always obtain a good price in the market; but if a whole farm were so cropped, nearly all the manure must be purchased ; for, after a few crops, the wheat-straw and bean-halm would not produce half tho manure re quired for the land. Hay and oats must be purchased for the horses required for the tillage, which might not be procured so readily or so cheap as they may bo raised on the farm. On very light sands wheat or beans cannot be raised, except by a very expensive mode of culti vation ; but rye, oats, peas, buckwheat, and roots for cattle must be subgtituted. On chalky loams the principal crops are barley and artificial grasses for sheep. In short, no particular rotation can be prescribed without a complete knowledge of the soil, the locality, and every circumstance connected with any particular farm. As the most universal rule, it may be laid down that every alternate crop should be consumed by animals on the farm, and that, as much as possible, the plants which succeed each other should be of different natural botanic families. Experience has generally shown the time that should bo allowed to intervene between the recurrence of tho same kind of crop, and we have only to form our plans accordingly.
Of the old triennial course (fallow, wheat, barley or oats) it must be observed that the two corn-crops so rapidly deteriorate the soil, that a complete year of fallow is required to purify it, and a good manuring to keep the land in heart, and that all the industry of the farmer cannot keep up the fertility of the land without extraneous help, either from the manure made in towns, or in the farm-yard by cattle bred and kept in commons or pasture-grounds. This system, which
prevailed so long, cannot be called a rotation ; and no real improve ment was introduced into agriculture until the notion of its perfection was exploded, and tenants were permitted to deviate from it. The rotations adopted in the place of this old system necessarily partook at first of its main defects. Green crops were introduced of necessity to supply the loss of the commons and matures, which, as the population increased, were gradually cultivated as amble land : but the two white crops remained In succession, and even now, such is the force of habit and early impression, that one of the most difficult points to be gained with practical farmers, accustomed to the old rotations, is to make them have patience when their land is in a good state, and to prevent their sowing a white crop, which is immediately profitable, instead of a green crop, which will keep the land in heart and improve it for future crops, but which does not figure in the accouut of sales. Yet it can be clearly shown, that in most cases the second corn crop is dearly purchased by the expense required to restore the land to the state in which it was when the aced was sown a second time: manure alone will not do this ; fallowing and repeated ploughing can alone effect it : and whether you plough several times before a crop, or are forced to do so after it, there is no difference in the expense of labour, although there may be much in the value of the subsequent crops.
The Norfolk course (turnips, barley, clover, wheat), which is so well known and deservedly in repute for light sands, has Maly one defect, which is the too frequent recurrence of clover. Rye grass, the usual estbsutute iu sandy soils, unto.. it be fed off young, is far inferior to clover se a preparation for wheat, and this accords with theory ; for wheat and eye gram are both of the natural family of the grentiartr. Tares or vetches are a good substitute in heavy mils, as well as bens, teeth of which are lrgaatiaoser, but not well suited to light sandy sells. Pea. are sometimes introduced ; but they are apt to encourage weeds, unitise the crop be very heavy, and then they exhaust the soil, and Iseve little vegatablo matter behind them in their roots.