Coconut planters manual. 122 



phere from the surface of the leaves ! These elementary facts are in 

 themselves sufficiently impressive to hring it home to all of us that hv 

 far the most important duty the coconut planter has to perform is that 

 of ensuring an adequate and constant supply of water to the palms. 



The water which enters the roots of the palm is not pure; it con- 

 tains dissolved within it small quantities of nitrogen Bad mineral plant- 

 food, such as phosphoric acid, iron, magnesium etc., extracted from the 

 soil. But the water which is evaporated off from the leaves of the palm 

 is perfectly pure. 



Nothing but absolutely pure water is allowed to escape from the 

 surface of the leaves. All the various salts which entered the roots 

 dissolved in the water are thus retained in the palm, and that is how 

 the palm feeds. 



It has frequently been shown hy chemical analysis that the top few 

 feet of all ordinary soils contain many thousands of pounds of all the 

 different food-stuffs necessary to plants, more than sufficient for the 

 requirements of a very large number of crops, and yet it is a matter 

 of common experience that additional food-stuffs in the form of manure 

 have to be applied to the soil before satisfactory crop growth can be 

 assured. The explanation of this is that the huge bulk of the plant-food 

 contained in the soil is in an insoluble condition. It cannot be dis- 

 solved in water and therefore the plant is incapable of absorbing it. 



Now there are a variety of ways by which we can help to render- 

 soluble the plant-food contained in the soil, the most important of which 

 is by means oT cultivation. 



By cultivation we admit air into the soil and we break down the 

 lumps of ear In and so expose a larger surface to the action of the air. 

 What that action is may not be generally appreciated, but it can be very 

 simply illustrated by considering the action of air upon a piece of iron, 

 such as a knife blade or a plough-share. Even a few hours' exposure to 

 the damp air is sufficient to cover such pieces of iron with a coating of 

 rust, which means that the oxygen of the air has combined with the 

 iron to form an entirely different substance, rust, or iron oxide as it 

 is called by the chemist. 



Every particle of soil exposed to the air is subjected to this same 

 action of " rusting " or " oxidation," and by this means large quanti- 

 ties of insoluble plant-food are oxidised into different substances which 

 can be dissolved in water and which are therefore of use to the palm. 



Various natural agencies are also at work ass:siing to render soluble 

 the plant-food in the soil, one of the most important of which is a gas 



