ROTATION OF CROPS.

Wanganui Chronicle, Volume LXXVI, Issue 18459, 18 April 1922, Page 10

ROTATION OF CROPS.

As harvesting operations are over in most districts, attention is now drawn to the scheme of cropping for the coming season. The farmer usually squares up accounts at what he terms the end of the farmers’ year, that is, at the end of March. Therefore, besides squaring up accounts, a scheme for cropping must be laid out previous to commencing operations. Stubble land intended for catch crops, if not already down, should be turned over as soon as possible. Where mixed farming is practised, it calls for much study and forethought on the part of the farmer, otherwise there will be serious leakage on the farm during the year.

Every detail, as far as possible, should be thought out and arranged, so that every operation in connection with the season’s work may run as smoothly as possible, and there will be no undue loss of time and labour. The rotation should receive careful consideration. It has been abundantly proved that a well-regu'ated rotation course is very essential, and that if some of our crops are grown upon the same ground year after year, difficulties arise which have to be overcome, or the crops will not grow healthy or luxuriant. The best way to overcome this is to keep these crops as far apart in the rotation as possible; that is to say, plants of the same habit of growth and character should not follow each other. Some plants strike deeply into the soil and obtain much of their • plant food from the lower portions of the so'il, ■whereas others send out their roots amid the surface soil, and are shallow-rooted. For this reason wheat almost invariably thrives well after clover lea, as the clover roots strike deeply, and really enrich the Upper soil by adding to it matter drawn from below, besides drawing into the soil a certain amount of atmospheric nitrogen, which is deposited there and used by the crop that follows. Wheat also does well after peas, beans, or vetches, the roots finding freedom for their growth. Producing Maximum Crops. It is nit sufficient for a farmer to know in what order crops grow best, but he should also know why certain crops flourish in a curtain position in the rotation. When he has mastered this problem, then he is in a better position to regulate his course of cropping. For instance, different crops require different kinds of food, and they therefore draw from the soil different kinds of inorganic matter. By the removal of our various crops from the land, we remove also large quantities of those inorganic matters which are necessary for keeping the land fertile. One of the great objects to be accomplished in successful farming is to make the land produce maximum crops, and at. the same time make it more productive every year, or at least able to hold its own, instead of becoming cropped out or exhausted. Generally speaking, the constituents which are removed from soils by plants, and the loss of which brings about a condition of exhaustion, are compounds of nitrogen, phosphoric acid, and potash. This is partly, at least, why farmyard manure is so universally regarded as the mainstay of the agriculturists, for that material contains all those ingredients, and in a form easily assimilated by plants. It must not be forgotten, however, that possibly the chief advantages derived from the use of farmyard manure are that it makes the soil more porous, and then the conditions ■which result from the decomposition of the organic matter are favourable to the development of those microorganisms w'hich bacteriologists are endeavouring to prove are of as much importance as the manure itself.

Artificial Manures. Artificial manures do not fulfil all requirements for all classes of crops. They nevertheless furnish valuable plant food to depleted soils and serve the purpose very well under the circumstances. The cost of saving and utilising farmyard manure in this country on anything like a large scale, is prohibitive, but whenever it is possible it should be applied to such crops as will make most use of it. The soil obtains its nitrogen from organic matter, from rain water and from nitrogenous artificial manures, added to the land. The organic matter found in soils, caused by the droppings of animals and plant life, and added in the form <f farmyard manure, undergoes a chemical change. This change is brought about by the agency of a minute bactorium or bacteria, which is present more or less in all soils, and which is increased by judicious manuring, together with good tillage, the latter being just as essential or even more so, than the former. These acids form nitrites and nitrates, with bases like lime, potash, soda, etc., contained in the soil and taken up by plants. There are two chief classes of manures, namely, direct and indirect manures. Direct manures act directly on the plant, while the duty of indirect manures is to improve the condition of the soil; thus these substances which act upon the soil’s inert fertilising matter, and by this action convert it into a more speedily available form than are other substances, exert a considerable effect on the texture of the soil, and thereby influence its physical an 1 biological properties. Lime, it might be said, under certain circumstances, acts in different ways. There are soils which are actually lacking in a sufficiency of lime for the needs of crops. On such soils an application of lime would act both as a direct and also as an indirect manure. W.S.