GASLIME.

Otago Witness, Issue 2085, 8 February 1894, Page 6

GASLIME.

The value of gaslime— a by-product of the manufacture of coal gas — is but little understood by farmers, else the means of getting rid of the material would not perplex the managers of gasworks. Those who do adventure on the speculation of buying it, advertise its efficacy when " aerated," that is to say — when ib has been exposed to the air for a longer or sborber period in order to deprive it of its caustic, pungent properties, and retail it in small quantities in its deteriorated condition, for deteriorated, from a farmer's point of view, afcale gaslime is. Aeration just deprives gaslime of the peculiar properties which constitute its special value when judiciously applied in its fresh state in due season. Farmers for no snfficent reason avoid its application in the condition in which it would have the most powerful and beneficial effects. Far more intensely active than quicklime, a sufficient dressing of caustic gaslime lightly grubbed in on stubble land in autumn will prove fatal to weeds and their seeds, and deadly to insect life. There are no cheaper means of cleaning foul lands or of purging the soil of larvae of insects such as those of Hessian fly, while wireworm, grubs, and slugs immediately succumb to it. It absolutely sterilises the land for some months, and hence its value when applied in the autumn, when it is desirable to kill weed vegetation. Early chemical authorities advised the burying of gas lime in pits and covering with earth because of the noxious fumes evolved from it, but only about 30 years ago these pungent properties were ascertained to have an exceptional value for farmers. The proper understanding of the characteristics of gaslime will be arrived at from a simple description of its production. Crude coal gas issuing from the retorts is charged with sulphuretted hydrogen, carbonic acid, and other gases, which if not extracted would greatly lessen its illuminating power. To free the gas from the deleterious combinations it is passed over shelves containing quicklime. This caustic lime becomes surcharged with the objectionable combinations in the gas, loses its absorptive power, and is cast aside as gaslime. The following is the average of constituents of the product : —

As will be seen from the above analysis, gaslime is partly in the form of carbonate, partly as caustic lime, partly jn the form of sulphur compounds: and with an appreciable proportion of alkaline salts. It ia to the caußtic lime, but chiefly to the sulphites and alkaline salts, that fresh gaslime owes its efficacy as a cleanser of foul and insect-infested soils ; but when exposed to the air for some time ("aerated") the potency of the caustic lime is impaired, while the sulpbjtes become more or less oxidised to sulphate of lime (gypsum), which is only of moderate mannrial value, and certainty not hurtful to hibernating chrysalis or grub, while a fertiliser of weeds, On the other hand, fresh gaslime, as already stated, is fatal to all forms of insect life, and not only destroys worms and grubs, bat also the roots of the vegetation on which they live. In an article on insect pests, Miss Ormerod, the well-known entomologist, writes :— " It is no harm, but very desirable, to kill surface vegetation by autumn dressing, and heavy applications of caustic gaslime when mixed with the soil will effect this and do nothing but good to the next crop Such dressings will also kill wireworms, grubs of daddy-longlegs (found in grass pasture, in the 3 roppings from cattle, and very injurious to grain crops after leys), Hessian fly, and grubs of all kinds." In the case of infested land which has been, or is about to be, put under cultivation, no reasonable efforts should be spared during the autumn to destroy insect pests and their larvae. Again, the luxurious summer vegetation is sure to leave a legacy of weeds, and for all purposes a heavy dressing of fre-h gaslime will proye tho most effective. The treatment wi)l thoroughly clean6e foul a,tubble land as no labour will, for even the seeds of weeds lying dormant in the soil will be deprived of vitality by the action of the sulphite and caustic Jime constituents of gasSine. The ideas as to the baneful effects of application of gaslime were occasioned Dy its use in springtime or immediately before seed-sowing ; but since its value as an autumn dressing has been ascertained we read in Home agricultural journals of up to two tons per acre being applied, and with moßt satisfactory results. The common practice is to scarify ft in, and long before spring it has effected the purpose sought — has formed new combinations and fertilised while cleansing the soil. Gaslime is good for all soils jn which lime is deficient, and is even preferable to other kinds of lime for

leguminous crops— clover, beans, peas, vetches, &c. Soils naturally deficient in lime derive much benefit from its application. Peaty land is greatly improved by it, a more luxuriant growth of herbage resulting. Like quicklime, it renders heavy soils more porous, and, on the other hand, it considerably consolidates light sands.

A correspondent writes in a late number of the Field that he applied three tons per acre to a rabbit warren, and that the herbage is so much improved he now makes a considerable profit from the greatly inoreased number of rabbits he is enabled to keep. Gaslime, like quicklime, being less porous than sand and more so than clay, has an improving effect on soils in which either sand or clay prevails, but it has also a special chemical effect because of the sulphites it contains. As all farmers know, lime acts most powerfully in its caustic state. Caustic or quicklime readily decomposes fibr.es of vegetable matter such as straw, heath, and the like. It helps their decomposition and accelerates it. By its means the dead fibres of vegetables which remain in the earth when the crop is removed become soluble, and their elements entering into new combinations supply the materials of other plant food. Tho use of quicklime in rendering inert vegetable fibres soluble, and hastening the decomposition of animal substances, is acknowledged to be of the greatest importance to agriculture. But gaslime, for the reasons given, is far more powerful, more searching; is a thorough cleanser of the soil from all obnoxious pests ; and the application of a much less quantity than that nseded of quicklime will give more satisfactory results. Wherever there is a considerable proportion of peaty matter in the soil, which in itself is perfectly incapable of putrefaction, owing to the tannin principle it contains, gaslime is the cheapest and best remedy. Assisted by feculent matter to produce heat and fermentation in if, gaslime soon dissolves peat and converts it into real humus, than which there is no better food for vegetation. Therefore it is that wherever peat is available gaslime is in demand for the preparation of composts when wanted specially for topdressing pastures.. We may again repeat that the best time to apply gaslime is autumn or early winter ; and where pastures are infested with mosses and probably wireworms, scwt or 6cwt to the acre, powdered and spread evenly, say about April, will ensure a healthy herbage in the spring.

dCoisture 1005 )rganic mater and water in combination... 1"5( Uumina and oxide of iron i ... 2'li Carbonate of lime 463 Caustic lime 20'8i Sulphite of li/ne 137 i Sulphate of lime 2'si Magnesia, alkaline salts, &c 24( insoluble silicious matter o'2!