t 567 ] 



933- The action of lime in decomposing orthoclase felspar 

 has been already mentioned in connection with potash 

 manures. Soils containing fragments of felspathic stone, 

 therefore, are benefited by the application of lime. 



934. Liming of the soil makes the crop earlier. Phos- 

 phates have a similar effect of hastening maturity of 

 crops. 



935. One or two tons per acre once in every 7 years is the 

 best method of applying lime on lands suitable for liming. 

 Lime has a tendency to sink gradually into soil ; hence the 

 necessity of repeating the application from time to time. 

 Generally speaking, calcareous regions are particularly fertile 

 specially for pulse crops. Clay-soil rich in lime is fertile for 

 most crops. 



936. Soils are sometimes marled i.e. given a dose of clay 

 containing 5 to 50 or even 80 per cent, of lime. The applica- 

 tion of marl to sandy soils alters their texture for good. But 

 marl must be found on the spot if it is to be econo- 

 mically applied. 70,000 or 80,000 Ibs. per acre every 10 or 

 12 years is the rate at which marl is applied. 



937. Lime exists in most soils in sufficient proportion, 

 about \ per cent, of Silicate of Calcium being contained in 

 most soils, the remainder, which is a more variable constituent, 

 being CaCO 3 . The presence of CaCO 3 in proportions of over 

 i per cent, can be detected by the addition of any dilute acid 

 which results in effervescence. Calcium silicate is much 

 more insoluble, though it is of equal value with CaCO 3 when 

 permanent fertility is taken into cosideration. Farmyard 

 manure contains Ca chiefly in the soluble forms of sulphate 

 and carbonate, but calcium silicate also occurs in minute 

 proportions. Lime, Calcium hydrate (CaH 2 2CO 3 ) and 

 Gypsum are readily soluble in water ; but ghuttng and 

 limestones (CaCo 3 ) are also soluble in water charged with CO 2 . 

 Rain water contains no lime, but well water and muddy canal 

 or tank water contains joo parts or over of lime in every 



