THE FARM.

Otaki Mail, Volume XXVIII, 28 January 1920, Page 4

THE FARM.

functions or lime in AGRICULTURE.

Lime is indispensable as a component of the bodies of plants and animals. It accumulates in the leaves 'of plants, but the" -roots and .seeds, as a rule,,.conrain only small quantities. Certain kinds of alga; inhabiting fresh and salt water have their solid parts composed almost wholly of carbonate of lime. A most important function of lime, either in the form of oxide (quid; or slaked lime) of of carbonate, is. to correct sourness or acidity of ;Ue soil. The presence of lime in the foil pro motes nitrification. An excess of limo in the form of oxide may, however, hinder 'the work of the vitrifying organisms until, by the absorption of carbon dioxide from the atmosphere, it is converted into carbonate.

Lime has the property of liberating several" classes of plant food from coinpounds in (he .soil. It acts upon decaying vegetation, liberating nitrogen in the form Of ammonia, which will be partly'taken up by the plants growing upon the soil: but there is a likelihood that some wiil escape, and hencejherej is danger of exhausting the soil by the excessive application of lime, especially in the form of quicklime. Again, lime liberates jiolash from such minerals as feldspar, and makes it available for The use of plants. This is perhaps the most important -cited of lime on soil. The heavy application of

quicklime may liberate potash at a greater rate than it can be used by the plants growing on the soil; consequently the exc-ss of fi=ee potash will probably be h, i by leaching, aud the

result will be the premature exhaustion of the soil. There is c\ery reason to believe thai carbonate of lime acts much more- slowly tlian quick or slaked lime i„ liberating potash or nitrogen; nor docs it destroy the humus, as quick and slaked lirue do. Hence the followbig proverbs lose much of their force when carbonate of lime is used as a substitute for quicklime:— Lime enriches the father, but impoverishes the son. Lime and lime without manure Will make both farm aud farmer poor. z certain crops, the application of potash manures to the soil will become necessary. On the other hand," our present knowledge indicates that a proper system of farming in most cases will avoid the necessity of buying nitrogenour manures. Finally, lime ameliorates the texture of many soils. Clay soils, if given a heavy dressing of quick or slaked lime, become more friable, and "jjl-atioii respond more readily J^" soi \ s are and manuring. ,, y ~ hc appUca . of lime, and may thus be conW cra . bl y unproved. Amouvt of Lime Required by Soils. ' Xqixed rules can be given as to the ..Jcffit of lime required by a soil. }l>t New Zealand soils would be benc-ii-ed by the application of from one to ~<vo toils of quicklime every live year.;, This is l>esl .administered in several dressings, but an acid soil may, ot eour.-e. require a heavy preliminary application. If pulverised limestone ,s use d instead of quicklime, nearly double the "weight will be required. In Southland the soils a, a rule require .more i«te than in most other parts of rxew Zealand. Heavy clay laud may , be much impnved. as stated above, by ! the application several tons of lime per acre.