COCONUT PLANTER'S MANUAL- 181 



since after the nitrogen has been completely absorbed the plant is left 

 with a bigger and more active root system and consequently draws upon 

 a larger area of soil for its food and water. 



" A deficiency of nitrogen is seen in a general stunting of the whole 

 development of the plant," says Sir A. D. Hall who also observes that: 

 "On most cultivated soils upon which cropping is continued and manure 

 .withheld to a point when there begins to be a serious falling off in the 

 yield through lack of plant food it is the want of available nitrogen 

 rather than of phosphoric acid and potash which determines the yield. 

 In other words the soil is much more rapidly exhausted of its available 

 nitrogen than of its available phosphoric acid and potash." 



Nitrogen starvation, is manifested by a yellowing of the foliage, 

 absence of growth and a poor, starved appearance generally. To plants 

 in this unhappy condition an application of nitrogen has the immediate 

 effect of changing the colour of the leaves to a rich dark green and en- 

 couraging the growth and development of all portions of the plant. 



Phosphoric acid, like nitrogen, stimulates the development of roots, 

 particularly in the case of young plants, but its principal effect upon th9 

 crop is to increase the flowering and fruiting tendencies and to hasten 

 maturity. 



The principal effect of potash upon plants is to assist in the process 

 of extracting carbon from the carbon dioxide of the atmosphere. It also 

 assists in the formation of fruit, particularly of those which contain 

 sour juices. 



Potash tends to prolong the life of plants and has a distinct effect 

 in hardening the woody tissues of plants. 



From a careful comparison of the effects of the three principal 

 manurial substances it is obvious that the most important of the three, 

 from the planter's point of view, is nitrogen. 



In the first place, ordinary soils are more deficient in nitrogen than 

 in any other kind of plant-food. Secondly, crops give a bigger return 

 in response to an application of nitrogen than to any other form of 

 manure. Thirdly, nitrogen is the most expensive substance applied to 

 the soil as manure, for which reason it is obviously necessary to exercise 

 the greatest care and judgment in the selection of the best form of 

 nitrogen to apply. 



Nitrogen can be applied in many different forms. Nitrate of Soda, 

 Sulphate of Ammonia Dried Blood, Crushed Fish, Oil Cake, all supply 

 this most important plant-food. The question at once arises therefore 

 as to which form will give the best return. 



