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The Liming Of Soils

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Great interest has again arisen in the use oí lime tor the improvement of soil, and the experiment stations have been working on the problems involved in its proper application. Perhaps no clearer and more practical exposition of the subject has appeared thau that of Dr. H. J. Wheeler of the Rhode Island station, presented in farmers' bulletin No. 77, on the liming of the soil, trom which the following extracts are made Lime is said to take the place of potash in certain chemical compounds which exi'jt in soils, thus liberating the potash and placing it at the disposal of plants. In this particular, gypsum (land pluster or calcium sulphate) is believed to act more energetically than carbonate of lime, air slacked or watei slacked lime. When soluble phosphates are appliec to soils deficiënt in lime and magnesia, the phosphoric acid combines with the iron and alumina of the soil to forin compouuds which are not readily utilized by plants. If, however, the soil is fairly well supplied with lime and magnesia, tbis transforruation is retarded so that the plant is afforded an opportunity to utilize much of the phosphoric acid before it becomes unassimilable. If a soil containing a certain inert phosphate of iron is heavily limed, it is believed that this phosphate wil] be changed into a form which the plant can utilïze. Lime may therefore not onlyhelp to maintain fresh applications of phosphoric acid for a long time in assiniilable condition, but it may, if applied in sufficient quantity, help to unlock stores of phosphoric acid which plantswouldotherwise beunable touse. Hilgard has abundantly demonstrated the great valué of gypsum (land piaster) in renovating "alkali" oils in the arid portions of the United States. Wherever too ruuch sodium carbonate (black alkali) is the cause of the unproductive condition of the soil the gypsum reacts with it, producing sodiuni sulphate and carbonate of linie, whereby the alkalinity may be sufficieutly reduced to render possible the profitable production of crops. In case protosulphate of iron and certain other poisonous compounds are present in soils, lirning sochanges them as to render them harmless to plants. When the remains of plants undergo decay upon soils deficiënt in carbonates of lime and magnesia, acid or sour humus is Hable to be produced, which is particularly noxious to most agricultural plants, though perhaps helpful to the growth of lupines and a few others. Such conditions are liable to occur even in upland and naturally well drained soils. Liming is in all sunh cases an effectual and probably the most economical remedy. Many clay lands when wet by rains are not porous enough to allow the water to pass through them with sufficient rapidity, in consequence of which they become waterlogged, and the air which is necessary for the healthful development of plant roots withiu the soil is excluded. ín times of drought also such soils cake readily, thus becomiiig more difficult to till and less adapted physically to the growth of plants. Liming is an elïective preventiva or remfcdy for all of these unfavorable conditions. Upon certain loamy soils, containing considerable clay, liming often renders the surface more friable and less liable to form a crust upon drying. The irnprovement of drainage brought abont by liming is one of the most effective meaüs of preventing surface washing. When heavy rains occur on limed soils, the water sinks into the soil, instead of rashing over the surface, carrying the fine soil partióles and thus producing gullies and washes. Soils composed of siliceous sand are frequently benefited by being rendered more compact by liming. On such soils carbonate of lime is preferable to air or water slacked lime, owing to thecaustic nature of the latter, and the best material to employ, where it is obtainable, is a clay marl containing a fair amouni of carbonate of linie. The clay, as -wel] as the lime, tends to materially improve the physical condition of the soil. II should also be the aim to increase the aruuunt of organic matter in such soils, by the use of muck and stable manures or by the occasional plowing under of a green erop or a sward.


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