The Temuka Leader THURSDAY, MARCH 6, 1884. WHAT FARMERS OUGHT TO KNOW.

Temuka Leader, Issue 1148, 6 March 1884, Page 2

The Temuka Leader THURSDAY, MARCH 6, 1884. WHAT FARMERS OUGHT TO KNOW.

AGRICULTURAL CHEMISTRY. ( Written specially for this Paper.) v. B( ME FACTS ABOUT PLANTS. Before proceeding to a consideration of the various means employed to refertilise soil such as by draining, ploughing, deep-ploughing, subsoiling, liming, irrigation, etc, —the prh cipal functions performed by plants must be glanced at. We have already noticed some of the sources of the food of plants —minerals and inorganic materials in the soil, carbon from carbonic acid contained in the air and dissolved in water, nitrogen from ammonia, and nitric acid in the air ami in water, saline substances in ihe soil, oxygen from the air and dissolved i.i water. When a

plant is burned a portion goes off in gas, and the remaining portion is termed the ash. Now here we have one of the main distinctions between organic and inorganic materials, The atoms of the organic compounds present in the plant, when heat is applied, are able to re-assort themselves and fly off as different gases ; the inorganic components are not however, so easily affected by heat, and thus they remain unhurt. The organic portion consists of combinations of carbon, oxygen, hydrogen, and in the choicer parts of the plant, as the grain, nitrogen. The inorgr.n.o portion consists of various salts and inorganic compounds, such as alumina, silica, common salt, chloride of potassium, etc. The inorganic constituents are just as essential to the growth and usefulness of a plant as the organic. In considering the various principles of plants, we will guage their utility by their relative importance m building up the bodies of man and animals. The components of plants in the living organism perform two distinct functions. Certain compounds called nitrogenous are flesh forming, others are termed respiratory heat giving or fat producing . Both of these divisions—the nitrogenous and respiratory—are necessary in the food of animals.

Of the nou-nitrogenous or heat-giving principles woody fibre or lignine forms the major part. “ In wheat, oats, grass, and all cultivated crops it is more or less abundant. Woody fibre in a matured state is useless as a feeding material ; it simply passes unchanged through the animal system, and in the case of our domestic animals forms the chief bulk of their solid excrements ; hence the amount of this substance materially affects the value of feeding materials. The imperfectly formed woody matter, as it exists in young plants and in the succulent portions of older ones, is digestible in the stomachs of animals, and seems to be nearly as useful to them as the other members of the group (the fat-pro-ducing division). As it is found that the proportion of indigestible woody fibre greatly increases as the plants reach maturity, we can to some extent account for the superior value of hay that has been cut early, in comparison with hay made from plants that have been allowed to arrive at a more advanced period of growth,” The other members of this group are starch, sugar, gum, mucilage, pectin, oil, or fatty matter, all of which perform one great function in the living organism, namely, that of supplying it with materials lor keeping up heat in the body. Sugar is present in abundance in the maple tree, sugar cane, and beet, as well as in carrots, turnips, etc. Starch is the great component of meal and flour. It occurs in greatest abundance in potatoes, carrots and other roots, also in sago, tapioca, arrowroot, etc. Oil and fatty matter is present in great abundance in linseed, rape, etc. After a large amount ol the oil has been pressed out of the gram, enough still remains to make the cake nourishing lor animals. And now, to consider how these materials sustain heat in the system. It will be remembered that the breath consists to a great extent of carbonic acid, a gas which is composed of carbon and oxygen, also that we are constantly inhaling oxygen and exhaling oxygen and carbonic acid, The substances whose names we have just mentioned consist to a groat extent of carbon. They form the source of the great supply of carbon to present to oxygen of the atmosphere, to combine with and form carbonic acid gas. Dr Huxley says : “ It is oxygen which is the great sweeper of the economy. Inti odneed by the blood, into which it is absorbed, into all corners of the organism, it seizes upon those organic molecules which are disposable, lays bold of their elements, and combines with them in the new and simpler forms, carbon acid, water, and urea. The oxidation, or in other words the burning, of these matters gives rise to an amount of heat which is as efficient as a fire to raise the blood to a temperature of about 100 deg. ; and this hot fluid incessantly renewed in all parts of the economy by the torrent of the circulation, warms the body, as a house is warmed by a hot water apparatus.”— Thus will be seen the important part that the non-nitrogeuous or heat-giving compounds play. They are also called carbonaceous because of the amount of carbon they contain. The hydrogen (another gas) present in them also forms another element that oxygen can lay hold of and combine with, thus producing ordinary water. Instances before have been often referred to, illustrating how heat is always liberated when two elements combine, and it is unnecessary to recur to them again. From the above facts it will be seen why cattle m cold weather and exposed to cold winds require more food than cattle sheltered and kept warm. They need more heat giving materials to sustain their warmth, the ordinary warmth of the sun having been withdrawn from them. When more carbonaceous food is supplied than is required by the animal, then it is stored up as fat, and kept till such times as it is needed. Oil and fatty matter in the plant we have already seen—such as in linseed cakes—is of great efficacy in fattening cattle. In fact, it appears in the animal little changed from what it was in the plant Thus, those combinations of elements in vegetable food that approach most nearly to the forms that animals mould them into, are the best fattening materials. For instance, starch when taken into the system has to undergo certain modifications before it assumes the shape required by the animal, while oil in linseed cakes is very soon converted into animal fat, if not directly

required for respiratory matter. Henc linseed cake is a much better fattening material than food the chief ingredient of which is starch. The office of this division of food i thus seen to be that of heat-giving or fat-producing compounds chiefly through the presence of carbon and hydrogen in them, which combine with oxygen in the atmosphere, thus liberating heat. These compounds thus cannot sustain life by themselves, nor do they form what we call wholesome or nourishing food.

We now pass on to the nitrogenous, or flesh forming components of food. These possess in addition to the elements of the non-nitrogenous division (carbon, hydrogen, oxygen) nitrogen, a gas we have seen that forms fourninths of the atmosphere. These compounds are used in building up the animal structure, to form flesh chiefly, hence called flesh-forming. They supply the body with materials tor restoring the constant waste going on in it. Their names are, vegetable albumen, vegetable casein, gluten or vegetable fibrine, and legmnme. All these compounds resemble each other very much, end by some chemists they are held to be all modifications of one substance, protein. Hence all these names are known by the one generic term, protein compounds. Annexed is a table showing the proportion of fleshforming principles and water in food : Gluten. Water. In 100 parts, Wheaten bread ... 6 45 Wheat (whole grain)... 12 16 Fine flour 10 14 Oatmeal ... „. 18 Beans ... ... 25 12 Cheese 29.45 36 61 Turnips 14 19 Carrots ... ... 6 87 From the above table some idea may he gathered of the relative flesh-forming capabilities of different vegetables and their products. The nitrogenous portion of the food of animals supplies the means, as we have said before, of renovating flesh and muscle which are wasted by exertion. Thus the nitrogenous food of man and animals is in direct proportion to the amount of work or exercise they undergo. The working horse requires more fleshforming food when in the plough than when idle; the cattle need more carbonaceous food in winter than in summer. Neither of these divisions, however, is able of itself to support life ; a judicious mixture is in all cases necessary. The difference in food needed by animals when working or idle, in hot or cold weather, is only in degree. And now, as to the mineral constituents of vegetable growth, What part do they play in sustaining life in the animal system ? Though comparatively present iu plants in very small quantities, they perform functions both useful in the growth of the plant and in building up part of the animal organism. The adaptations of nature are constantly displayed when considering the wonderful structure and growth of vegetable life, and how they are moulded to suit the various functions plants have to perform. Lime is necessary in the animal system, As a phosphate (that is, combined with phosphoric acid), it forms the hard unpliable portion of bone, Salt helps digestion, etc,, and when cattle have not sufficient of it they have been known in America to rush in herds to “ salt-licks,” And so with the other mineral and inorganic components of plants ; they all play their own part in the great round of Nature. In our next article we propose to briefly consider some of the methods of re-fertilising soil. {To be Continued.)