FARM TOPICS.

Colonist, Volume LI, Issue 12679, 26 October 1909, Page 1

FARM TOPICS.

As every farmer knows, the presence of acidity in a soil is injurious to vegetation. It gives rise to some well-recognised plant diseases, such ns "fiiiger-and-t-oe" in turnips, and there arc plants, such as lucerne, that will not grow in acid soils. What are the usual causes for this unfavourable condition of tlie soil? An effort to explain them is made in Bulletin No. 93 of Soil Studies, issued by tlie Florida Agricultural Experiment Station. Among the principal causes arc attributed : — 1. The decomposition of organic matter accompanied by the formation of various organic compounds, including the production of organic acids. 2. The action of soil bacteria upon certain portions of tho vegetable matter in tlie soil. 3. The breaking' up of mineral fertilisers. Thus, when sulphate of ammonia is decomposed in the noil there is a formation- * of free acid in the soil solution, which is injurious unless counteracted by the- presence of a sufficient supply of lime in the soil. It is possible that to the acidity so produced in the absence cf adequate lime may be attributed tin; unsatisfactory results which have sometimes been noticed from the use of sulphate of ammonia in sandy acid soils. 4. The fermentation of green materials. When a heavy crop of green material is ploughed under fermenta- • tion will set Ln if the conditions of temporature and moisture are favour- * able, and as a result the soil may '■ become sour unless it is well supplied with bases, such as lime, magnesia, etc. - • It would apply from the result of , experiments that for practical farm purposes tho i>eutralLsing effect of applied lime is not" exerted below the , depth .to -wliich it i*r incorporated with the soil during the various processes of preparation ■; ar.d ' cultivation. Consequently, the .more thorough and the deeper these operations arc the better the distribution and the more effective the action of the lime. The knowledge /thus obtained on these points, enables us to say tbat ! the incorporatian. of .lime 1 with 3in • or 4ia of surface soilis -sufficient tb . I produce marked effects antacid soils, ! and also tliat at. any time it is need-. ! less and possibly occasionally harmful, so far as the immediately sticCeCuing"; crops axe concerned, to apply more lime, than ? will . neutralise tha coil to a depth to which, it is to be ' cultivated. It is the better farm

practice, therefore, to apply only this amount of lime, and immediately after the next ploughing to repeat tho application and work it iv. Tliese results indicate that alkaline soils aire more fertile than acid soils, aud produce crops more economically than acid soils do; that in applying lime tlie soil should finally be made allkalino to the full ploughed depth; that in; -ordinary, farm practice tho acids of tlte subsoil are not neutralised by applied lime.