SCIENTIFIC.

Otago Witness, Issue 1915, 3 August 1888, Page 35

SCIENTIFIC.

OHEMibTRT AT THE FARM.

By F. A. Joseph.

No. XII.

Tanners' bark is another waste material which possesses, like sawdust, a cerlain manurial value. Formed into a compost with lime or liquid manure, it makes a good fertiliser. The liquid portion of stockyard manure, which is commonly allowed to run to waste, could in this way bo profitably used. Where fall is available, pits should be "dug to catch the liquid, and the pits should be filed with sawdust, peat, tanners' bark, or other waste material, when an excellent manure would result from substances generally, allowed to go to waste ; and a very large quantity could be so prepared by every farmer who keeps a few cows~ The gain * '* -■ - ' * j "(Continued on'jgtge $7.}' y '*'

would amply repay the trouble. The clippings of wool lying so plentifully about every shearing shed form another waste product, very rich in nitrogen and potash, and therefore possessing a high manurial value. Either 1 digested with sulphuric acid or fermented in the liquid manure pit, this Waste product would be converted into a valuable material. Powdered charcoal and soot also form good manures. Charcoal has a wonderful power of absorbing acids, and therefore must act beneficially upon sour lands. It also absorbs oxygen from the air, and in this way helps to oxidise compounds in the soil, breaking them up and liberating their useful elements for plants. Soot is only another form of of charcoal, retaining in concentrated form the elements of the wood or coal from which it was derived. Ammonia, gypsum, and nitric acid are found in soot. Both soot and charcoal are excellent dressings for flowersj when applied freely round the roots of roses, dahlias, &c, causing the flowers to be richer and • darker in shade. Land top- dressed with soot yields better crops of oats and wheat. Experiments have shown land so dressed to yield about 10 bushels more to the acre. Soot, applied in the proportion of 56 bushels mixed with six bushels of salt, has produced larger crops of carrots than 24 tons of farmyard manure mixed with 24 bushels of bone dust. Soot is therefore a valuable manure, which is too often allowed to go to waste.

Coal dust is sometimes employed as a manure, bnt it is one of Very low value. Uoal ash is a good manure, but it requires to be mixed with something else, as lime or bone dust. In fact, whole bones, packed in coal or wood ash moistened, will in a short time crumble down and make a valuable manure. Gas lime, another waste material, may be used as a manure. Its composition is a mixture of calcium carbonate, sulphate, and sulphide, along with a trace of ammonia and other substances. The calcium sulphide is the objectionable compound, inimical to plant life ; and before gas lime can be used as a manure it must be long exposed to the atmosphere till all its sulphide becomes converted 'into sulphate. When that change takes place it forms a fairly good manure. Gas lime is generally used for the destruction of obnoxious weeds, amd for that purpose no better agent could be employed, as, after doing its work of destruction, it changes its character and becomes a manure. The waste material of the slaughter-yard generally represents a high manurial value, and even horns and hoofs may be converted into good nitrogenous manures by the aid of sulphuric acid. Coal shale, although an unlikely looking substance, yet may be applied with advantage to soils deficient in vegetable matter. Any farmer in the vicinity of a coal pit could easily experiment with the waste black shale which covers the coal, and so test its manurial value. There are other fertilising agents which may be thought of by the intelligent farmer who takes science on his side and reasons from that sure standpoint. Circumstances must determine in each case the value of any fertiliser easily available.

jlg nas oeen tor the purpose of impressing upon the farmer the importance of scientific teaching in relation to farm work, as opposed to traditional or rule-of-thumb methods, that these papers have been written, and not so much in the direction of teaching agricultural chemistry, which, I quite well know, could not be so taught. Yet those who have carefully followed me in the series of papers will have a clearer conception of much relating bo their everyday work than those who have not read at all on the subject, and who are content to go on the old way their fathers did before them for generations. I have endeavoured to place in as clear a light as was possible within the compass of a short series of papers the rationale of plant life in relation to its surroundings, and. how to bring about the most favourable conditions for healthy growth. The chemical composition of the plant has been referred back to the soil whence it sprung, demonstrating that healthy plants can only be grown in soil in which all the essential constituents which enter into their structure are available in proper form. It has further been pointed out that no matter .how great the quantity of insoluble constituents may be in a soil, for, so long as these componds remain in that state, the plant cannot use them. The readiest methods of converting insoluble into soluble compounds have been given. Drainage, subsoiling, and dressing with lime are, perhaps, the most essential. The exhaustion of soils by continuous liming has been referred to, and instructions given how to keep up the fertility of the soil by supplying other substances at the same time. The chief chemical substances entering into the composition of manures have been mentioned, and various sources, usuallyneglected, whence good fertilising agents may be obtained have been briefly dealt with. Thus I have attempted to bring into focus, as it were, a scattered array of crude matter, so that the merest tyro in agricultural science might learn something of how best to utilise the substances at hand. But it must be understood that my task has been imperfectly performed , for the field is a very wide one, and could not possibly have ample justice done to it in that way. Still what I have done, I trust will be of some use to someone. The knowledge that even a few farmers have learned some practical lessons out of the series of articles will satisfy me that they have been of some use. So leaving the matter there for tb.3 present, I must conclude.

f — A new ouilding material called stonebrick is said to possess extremely useful qualities and to be likely to come into extensive use. It ia made by grinding together lime and sand in a dry state. It is then heated by steam and becomes burned hydraulic cement.

— An instrument called the autoerraphometer has lately been devised, which autographically records the plan of the ground over which it is dragged. It can be carried about on a light vehicle, and when in use indicates the topography and differences of level of all places over which it passes.

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