COCONUT PLANTER'S MANUAL. 115 



all the roots when the whole area is cultivated and not merely a circle 

 round each tree. Another important result of cultivation is that air is 

 by this means allowed to enter the sod freely. Air is necessary for the 

 growth of the multitudes of bacteria which exist in the soil and which 

 perform many duties in the way of bringing different plant foods into 

 the condition in which they can be used. The nitrifying bacteria, for 

 instance, produce nitrates from other nitrogen com[ ounds. and until 

 these compounds are converted into nitrates few plants can use them. 

 These nitrifying organisms can only live in presence of air, and a well 

 aerated soil contains many more than a compact and badly cultivated 

 soil. It has been found in laboratory experiments that 25 times as much 

 nitrate is formed in soils which have been stirred as in those left undis- 

 turbed. Besides this, air is directly necessary to growing roots. A good 

 example of the need of roots for air is seen on turning out the soil from 

 a flower-pot in which ferns or other plants have been growing for some 

 time; a felted mass of roots is found lining the inside surface of the 

 pot, having grown there in profusion as the result of the air which enters 

 through the pores of the earthenware. Plants cannot be grown in pure 

 clay, the soil particles are so fine and become so closely compacted that 

 no air can enter, the roots cannot develop and the plants soon wither 

 and die. 



It is evident, however, that the amount of cultivation which a soil 

 needs depends on its texture. Thus the pure clay just mentioned could 

 be made to support plant life if it were possible to keep it constantly 

 stirred, while lighter soils would succeed with much less stirring; and 

 so, in general, heavy clay soils need more cultivation than light sandy 

 soils. A good deal of attention is being paid at th- present time in 

 Ceylon to what is called dry-farming. By this is meant the cultivation, 

 without irrigat.on, of lands where the rainfall is insufficient to support 

 heavy crops W'thout special methods. Ihe principles of dry-farming are 

 neither more u less than the principles which should govern all farm- 

 ing, namely the proper conservation of soil moisture by cultivation so 

 that the maxm-um amount is available for the crop at the time when 

 it is most neeued. 



A soil to be in the best condition should resemble a moist sponge. 

 It should be able to draw up moisture from great depths by capillary 

 attraction to the region where the growing roots are, and should be 

 covered by a layer of loose surface soil which prevents that moisture from 

 being lost by fvaporation. 



In the case of heavy, or even moderately heavy soils the matter 

 is comparatively simple, and the danger of over-cultivation is not great; 

 but in very loose, sandy soils, such as are often planned with coconuts 



