ROTATION OF CROPS.

Globe, Volume XXII, Issue 1993, 14 July 1880, Page 4

ROTATION OF CROPS.

[From the “ Weekly Press.”]

Although the success of a farm materially depends on a knowledge of the varieties of the soils of which it is composed, their fertile properties and capabilities of improvement, it is nevertheless essentially necessary that a suitable course be pursued in the changes or rotation of the crops. Tha greatest novice in farming knows that if ho grows tho same hind o- crop several times in succession on the same land, it will ultimately become so exhausted as to be unable to produce that crop any longer, therefore the least enlightened agriculturist practices a rotation of soma description. Though a soil may bo exhausted as regards one crop, yet it may be fertile to another; and while is may bo incapable of bearing an additional crop of tho same sort as the lost grown upon it, one of a different kind may flourish and come to perfection. The fact ■was iu olden times accounted for by the theory that plants during their growth -excreted certain compounds, and that each tribe of plants produced a different kind of compound, which, although injurious to tho plant that produced it, exercised a beneficial result on soma other spscies of plants. Thus it was believed that several crops of the same kind would not grow successively on tho same field, because the exorementitious substances left in the soil by the growth of these crops were present in too large a quantity to admit of the further healthy growth of the same crops, and for the same reason the ground was supposed to bo in a favorable condition for bearing some ctbor family of plants that could appropriate and thrive on these particular compounds. This notion, though very popular some time age, is quite exploded in the present day. The most probable cause of the soil being unable to bear many crops of the same kind iu succession is explained by the fact that each tribe of plants requires a certain kind and a certain quantity of mineral or inorganic matter for its support, and if a soil is not capable of supplying these materials in sufficient quantity these plants will not flourish upon it; and if the mineral substances required by these plants are not present in the soil at all they will not come to perfection. This is plainly seen in moat cases when wheat is sown after wheat. The second crop generally promises pretty well up to the time of forming the grain, when its strength appears to fail suddenly, and the crop falls off with a miserable, blighted appearance, and is utterly valueless. By applying farm yard manure regularly and ia proper quantities, one kind of crop might be grown successfully and for any length of time, as this manure contains all the necessary substances, but there would bo a gradual accumulation of those substances not required by that particular crop, or only required to a email extent, which would thus represent so much idle capital. There is a greater difference between the food required by green and forage crops than between any two grain crops ; therefore, in a well arranged system of rotation two grain crops are never taken from the land in succession. Every material difference in the nature and quality of a soil will require a proportionate change in its management, so that each crop may work in a way most advantageous to the whole. Unless this point is rightly understood, the most persevering industry and economy will not avail much, except on some of the best soils in the country, in which case, though extra cropping may be pursued without injury, the same course under ordinary circumstances would not only be most injudicious, but would soon reduce the land to a barren, unproductive state. There are many difficulties in the way of a good system of rotation being adopted by colonial farmers. Our population is still email, and the home consumption of many kinds of agricultural produce is necessarily very limited. In deciding whether a crop ia suitable to his land, the farmer must also consider what proportion the expense of producing it bears to its marketable value when grown. There are some crops that form an important and necessary part of a regular rotation, but which are raised at so great an expenditure of labor and manure that they do not yield on the average a direct return equivalent to tho expense of raising them. Take for instance a potato crop which, as is well known, will not flourish without a plentiful supply of suitable manure, unless planted in new land or rich alluvial flats, and also involves a good deal of labor in planting, weeding, ridging, &e,, so that by the time it reaches the market, the proceeds of the crop, at the present price, barely covers the cost of growing, or at any rate leaves a very small margin of profit. Some years ago, when new land was easily obtained and the price ranged from £6 to £lO per ton, potatoes were one of the most profitable crops that could be raised. Pease, beans, pulse,&o., form important features in English rotation, and may be grown with advantage. in a complete system of high farming, and by small farmers near a largo town, but are scarcely applicable to an extended scale of farming on a system of rotation without manure, which is the only aystem colonial farmers can pursue until the E resent state of depression and low prices as passed over, and the country becomes more populous and more prosperous. Glover is also used as an annual in the alternation of crops, according to the English system, being usually sown with barley, but without the land is naturally rich or well manured, clover, according to the experience of most Canterbury farmers, does not attain a very luxuriant growth in the space of one year, either for feeding or mowing. All leguminous plants, such as turnips, clover, luoern, mustard, have, on account of their large leaf surfaces, the power of assimilating nitrogen from the atmosphere, and storing it up for the benefit of the succeeding crop of wheat, which has not the power of rapidly appropriating its food iu this manner. As wheat is at present our most profitable crop, it should deserve our attention to its need of ammoniacal nourishment, which cannot be better or more fully supplied than by ploughing in a crop of mustard. This plant ia said to be an excellent medium for collecting and condensing nitrogen in the soil. Its tap root also penetrates Into the subsoil end extracts inorganic food, which by tho decay of tho plant becomes incorporated with the surface soil, and is thus supplied to the wheat roots. Professor Johnston has stated os his opinion that a green crop ploughed in enriches the soil as much as the droppings from green food three times as great. Lucerne ia very similar to mustard in its habits and manner of growing, and being of rapid growth is well adapted for ploughing down in time for wheat sowing. This system of green manuring ia a favorite means of renovating the land in all old-established arable countries, and is well worthy the consideration of all advocates of good farming. The county of Norfolk has long been celebrated for its four-course system of rotation of crops in the following order—turnips, barley, clover, wheat; but every intelligent farmer should adapt his system to hia own soil and climate. The climate of Norfolk is inclined to be dry, and the soil is of a gravelly nature, so that it is in these respects not unlike the Canterbury plains. Tho following course, though not in accordance with the principles which rule a correct rotation, yet is one very well suited to the good land of this district, viz., turnips, wheat, clover, wheat, barley, oats. As the colonial farmer’s principal idea is get as many grain crops as possible out of tho land, the above course should meet with approval. In the British farmer’s notions of agriculture it is wretchedly bad farming to take two white straw crops in succession, but with judicious management, on good land, it may be practised successfully. In connection with the rotation of crops, the farmer must bear in mind that he must work hand in hand with Nature. Every plant that grows is subject to the unchangeable laws of Nature, which the cultivator of the soil cannot set aside or neglect if he hopes to meet with any success in his operations.