ON THE LAND

Wairarapa Daily Times, Volume 45, Issue 13794, 26 March 1919, Page 3

ON THE LAND

(By " Agricola.' ')

Acidity in Soils. Nothing i» ho injurious to tho growth of ordinary farm plants an acidity of tlm noil in "which they are growing. For fertility tho soil should bo neutral or vorv slightly alkaline It ia only uader these conditions that the putrefying and nitrifying bacteria can work effectively for the prdduction of available plant food. Tho chief cause of acidity in soils is tho production of organic acids during the decomposition of vegetable and mineral matter in tho absence of air. This kind of decomposition occurs most common in water-logged soils, such aa peat beds and in undrained clay soils. The amount of acid formed in theso conditions is often considerable, so much so that it dissolves the oxide of iron into tho sand o r other material below tho soil, gradually bleaching it. A curtain amount of acid is also formed in the process of nitrification, but unless this is immediately neutralised by tho carbonate of lime in the soil the process is quickly stopped. .For this reason lime iw essential to the complete fertility of any soil, and the more organic, manure, such as farmyard manure, is used the. great..;r is the need of lime. Acidity may also be brought about by the use of acid artificial manures, siic.h as superphosphate and sulphate of ammonia, on .soils already deficient in lime. Both the above mauuros may contain small quantities of free acid left in them in the process of manufacture, which combines with and neutralises''the lime n the soil. There is also the acidity produced in the nitrification, of the sulphate of ammonia.