An essay on tropical agriculture |
Términos y frases comunes
abundant advantage afford Agricultural Chemistry agriculturists alkalies alumina ammonia amongst analysis applied ashes atmosphere burned cane cane-plant carbonate of lime carbonic acid cattle chemical clay combined comminuted compost compound considerable constituents crops cultivation decay deep derived doubt drains dung earth effect elements especially excrements expense experience fact farm-yard farmer fermentation fertility gaseous give green manuring growth guano gypsum heaps importance improvement increased ingredients inorganic labour land large proportion less lime liquid manure loss magnesia marl materials mineral matters moisture mould nature necessary nitrogen observe organic matter oxygen phosphate of lime phosphates phosphoric acid plants plough potash practical principles produce Professor Johnston quantity rain roots saline salts says Liebig scientific silicates soil soluble subsoil substances sugar sulphate of lime sulphuric sulphuric acid supply surface tained tillage tion urine valuable vegetable matter water stagnates whilst yield
Pasajes populares
Página 42 - Humus acts in the same manner in a soil permeable to air as in the air itself; it is a continued source of carbonic acid, which it emits very slowly. An atmosphere of carbonic acid, formed at the expense of the oxygen of the air, surrounds every particle of decaying humus. The cultivation of land, by tilling and loosening the soil, causes a free and unobstructed access of air. An atmosphere of carbonic acid is therefore contained in every fertile soil, and is the first and most important food for...
Página 13 - Vegetables produce in their organism the blood of all animals, for the carnivora, in consuming the blood and flesh of .the graminivora, consume, strictly speaking, only the vegetable principles which have served for the nutrition of the latter. Vegetable fibrine and albumen take the same form in the stomach of the graminivorous animal as animal fibrine and albumen do in that of the carnivorous animal.
Página 21 - Is it possible, after so many decisive investigations into the origin of the elements of animals and vegetables, the use of the alkalies, of lime and the phosphates, any doubt can exist as to the principles upon which a rational agriculture depends ? Can the art of agriculture be based upon anything but the restitution of a disturbed equilibrium ? Can it be imagined that any country, however rich and fertile, with a flourishing commerce, which for centuries exports its produce in the shape of grain...
Página 64 - 26-7, and that of winter wheat 3-33 per cent. Such great differences must be owing to some cause, and this we find in the different methods of cultivation. An increase of animal manure gives rise not only to an increase in the number of seeds, but also to a most remarkable difference in the proportion of the substances containing nitrogen, such as the gluten which they contain.
Página 63 - NITROGEN. WE cannot suppose that a plant could attain maturity, even in the richest vegetable mould, without the presence of matter containing nitrogen; since we know that nitrogen exists in every part of the vegetable structure.
Página 64 - The employment of animal manure in the cultivation of grain, and the vegetables which serve for fodder to cattle, is the most convincing proof that the nitrogen of vegetables is derived from ammonia.
Página 4 - Cultivation is the economy of force. Science teaches us the simplest means of obtaining the greatest effect with the smallest expenditure of power, and with given means to produce a maximum of force. The unprofitable exertion of power, the waste of force in agriculture, in other branches of industry, in science, or in social economy, is characteristic of the savage state, or of the want of knowledge.
Página 53 - As we find sugar and starch accompanied by salts of an organic acid ; and as experience proves that a deficiency of alkalies causes a deficient formation of woody fibre, sugar, and starch ; and that, on the contrary, a luxuriant growth is the consequence of their abundant supply; it is obvious that the object of culture, viz., a maximum of crops, cannot be obtained, unless the alkalies necessary for the transformation of carbonic acid into starch and sugar are supplied in abundant quantity, and in...
Página 4 - Not only the art of the farmer, the general direction of the operations of husbandry, but many inferior branches of country labour require much more skill and experience than the greater part of mechanic trades.
Página 13 - The animal organism is a higher kind of vegetable, the development of which begins with those substances, with the production of which the life of an ordinary vegetable ends.