Farm and Garden.

Alexandra Herald and Central Otago Gazette, Issue 440, 22 September 1904, Page 2

Farm and Garden.

ORIGINAL ARTICLE S. FERTILIZER CONSTITUENTS. ALL agricultural plants consist essentially of ton chemical elements, the proportion of these different elements varying quite widely with different plants. By the term element is meant an individual substance which cannot be divided into two different substancos. The ten elements are carbon, hydrogen, oxygen, calcium; magnesium, iron, sulphur, nitrogen, phosphorous, and potassium. Carbon usually constitutes about forty per cent, of the dry plant. It is obtained by the plant from the inexhaustible supply of carbon dioxide which is contained in tho air. This compound carbon dioxide is absorbed by the plant through the leaves or ochor green parts. Hydrogen and oxygen are tho two .elements of which water is composed, and !they aro obtained by the plant chiefly in this form, the compound water being absorbed by the plants. The hydrogen and oxygen usually compriso more than fifty per ccni. of the plant.. Many of the important constituents found in plants consist entirely of only carbon, hydrogen, and oxygen. That is the case with sugar, starch, cellulose or fiber, and most fats or oils. The four elements obtained from tho soil are. calcium, magnesium, iron, and sulphur; but the amounts of these olemonts required by plants aro very small compared with the quantities which practically all soils contain, consequently none of . those four elements is likely to become deficient in the soil. .The'three remaining elements—nitrogen, phosphorus, and potassium—aro required by most agricultural plants in very considerable quantities, and they are contained in nearly all soils in quite limited ..amounts; consequently if,crops aro grown Said removed from tho land 'for a long series ]

years, the supply of one or moro of these three elements is liable to become so greatly reduced that the crop yields become smaller than where produced on the virgin soil ultimately the yield becoming so greatly reduced that cropping ceases to bo profitable. In such cases the yield of the crop can usually bo more or less increased by applying to the soil that one of thoso three elements which is most deficient in the soil. • • .

Beoause of these facts materials containing considerable amounts of one or more of these throe elements have become a commercial value. Thus sodium nitrate, which is found in large quantities in some parts, is valued for the nitrogen it contains ; bones and rock phosphate are valued for the phosphorus they contain; and potassium chloride, and potassium sulphate, obtained from the very extensive mines in Germany, are valued for tho element of potassium which they contain. These three elements of plant food—nitrogen, phosphorous, and potassium—are contained in ordinary commercial fertilisers. If all the three are present, the material is then called a complete fertiliser ; if only one or two of the elements are present, it is called an incomplete fertiliser. In general farming there is practically no use for any so-called complete.fertiliser. First, because by means of leguminous crops, such as clover, peas, and other plants, one can obtain nitrogen from the inexhaustible supply of tho air at a very small cost; also a soil very rarely becomes deficient in both phosphorous and potassium. General applications of tho one which is most needed will give about as good results and much greater profit than both together ; although it is only the element itself which possesses any valuo for the plant, yet the plant can make uso of the element in many different forms or compounds—indeed, plants cannot- use these elements if applied in the free or, uncombined state. They must be present in some suitablo compound. If a soil is deficient in potassium that element could be supplied in tho potassium-chloride, a compound of tho two elements potassium arid chlorine, containing in the common market grade a,bout forty-two per cent, of potassium, or the potassium could be supplied by potassium sulphate, a compound .of potassium, sulphur, and oxygen—the ending ' ate' always indicates oxygen in a chemical compound, which usually contains about forty per cent, of potassium. Kainit, a crude minoral containing ten per cent, of potassium, is also sometimes used to supply that element. Of course, the value of any of these materials depends primarily upon the percentage of potassium it contains. As a rule, potassium can bo obtained cheaply in potassium-cloridc bettor than in any other form; phosphorous is commonly obtained in the form of calciumphosphate, a compound of the three elements calcium, phosphorous, and oxygen—as the name indicates. In per fectly pure form, this compound contains twenty per cent, of phosx>horous; but it cannot be obtained commercially in pure form. Good steamed bone meal contains from sixty to sixty-five per cent, of calciumphosphate—that is, from twelve to thirteen per eent. of the element phosphorous. , A good quality of ground rock phosphate also contains about twelve to thirteen per cent, of phosphorus. If the steamed bone meal costs six pounds a ton, then the phosphorous costs sixpence a pound. Steamed bone meal is known to be one of ■ the very, best forms of phosphorous, and bone meal is also a farm product; but the ground rock phosphate is a very much cheaper form of phosphorous, although it is considered much less readily available in the soil. Good seod alone will not make a good garden. Unless they are properly planted, the results will be anything but satisfactory, ■ be they ever so good. In order that seeds may germinate they must be.supplied: with, a certain degree of moisture and warmth, varying with the different varieties. Some varieties, for instance, will germinate at a temperature as low as 35 degrees, while others require a temperature of 85 degrees. Light must also be excluded until the roots, can derive nourishment from the soil. The first effect of air, heat, andmois--ture on the seed, says a standard work on the subject, is to change its starchy matter mto the proper food for the embryo. If, at" this time, the seed be withered by exposure to heat without sufficient covering, it will perish. It of tens happens that the seed's are. planted in freshly dug soil, and the above change in the properties of the seed takes place, but the earth not being pressed upon it, the seed dries up and the embryo perishes. Others, again, are buried too deeply, and though the seed swells, yet sufficient air and warmth are not obtained to give the embryo life. The seed should be just so far recovered as to exclude tho light and afford barely sufficient moisture for its wants. The first thing in sowing is a thorough preparation of the soil; It must be well pulverised, and should contain the requisite amount of moisture, so that the young root will find its surroundings congenial and be encouraged to supreme efforts. After the seeds have been put in the soil the earth should be firmly pressed upon'them. The subsequent growth of the plant in a large measure depends upon*the care given the seod and the early cultivation of the plant, in the same manner as the after-life of the child depends upon the care bestowed upon it in infancy.