I 4 THE RUBBER TREE BOOK 



" Lime itself can be shown in the laboratory to possess but 

 little flocculating power, for although its basis is calcium a 

 highly-effective metal it is combined as a hydrate which has 

 a deflocculating effect. However, as soon as lime is supplied 

 to the soil it becomes converted into carbonate, and some of 

 it will always be going into solution as bicarbonate, a salt which 

 possesses great flocculating power. 



" In practice, the application of such small quantities as a 

 ton, or even half a ton, to the acre have the greatest value in 

 ameliorating the working of clay land. Not only does it move 

 more readily and fall more easily into a good tilth, but, by 

 becoming coarser grained, it allows rain to percolate more 

 freely." 



It will thus be understood how it is the case that, while 

 lime is the means of assisting certain beneficial bacteria and of 

 setting free mineral food, it still has, in the form of bicarbonate, 

 an active effect in causing the fine clay particles to cling to- 

 gether, enabling a better aeration of the soil and a freer percola- 

 tion of water to take place, and greatly diminishing the resist- 

 ance of the stiff soil to the growth and expansion of the tender 

 rootlets of the trees. 



Mr E. J. Russell, of the Rothamsted Experimental Station, 

 puts the case of lime or no lime in the following words: " In- 

 jurious and inhibiting factors are of various kinds and form a 

 highly vague group, but some of them must be put out of action 

 by lime because of the striking effect which it has on soil 

 fertility. Indeed, from the vegetation standpoint, soils can 

 be divided into two main classes those which contain lime 

 and those which do not. So great is the distinction that the 

 practical man has long since made use of a separate name for 

 the latter soils and calls them ' sour/ a term which many 

 writers not altogether correctly interpret as acid." 



Sometimes, when a surface-soil is very light and porous, 

 it may well be the case that tropical rainfalls have washed out 

 most of the soluble mineral salts. It is scarcely correct to 

 judge of the quality of the soil of an estate by means of a 

 chemical analysis of portions of such surface-soils. The sub-soils 

 are frequently quite rich in the principal chemical elements 

 required for plant food, and, given a good rainfall, rubber, 

 although possibly hard to establish, ultimately comes away 



