CHAPTER IX 



MANURING 



The word manure formerly only applied to animal 

 excreta, but it has to-day a far wider meaning, for any 

 substance added to the soil to increase its fertility is 

 considered as manure. 



It may be applied either with a view to increasing 

 the productiveness of soils or to renovate and restore 

 the fertility of soils worn out by repeated cropping. We 

 know that plants derive their nourishment from the soil 

 and the atmosphere, and also the particular nutritive 

 elements which are respectively furnished by these two 

 sources. Provided that the cocoa planter establishes his 

 plantation on land adapted to the cultivation of cocoa, 

 it may be premised that if he annually returns to the 

 land manure containing equal quantities of the elements 

 which are removed by his crop, his debit and credit 

 account in regard to the soil should balance. 



This reasoning is sound from a purely theoretical point 

 of view, but unfortunately it is not applicable in practice. 

 For the planter has no means of ascertaining the amount 

 of plant-foods lost by drainage nor the changes brought 

 about in the soil by climatic and bacterial agencies. 



Reasons for Manuring. — Experiments conducted at 

 Rothamsted have shown that 7'21 lb. of nitrogen per 

 acre were deposited by rain, snow, and dew from the 

 atmosphere, but the loss of nitrogen by drainage, in the 

 form of nitric acid, was much greater than that deposited 

 from the atmosphere. Further, irrespective of the 

 excellent results obtained by nitrogenous manuring, 

 when ammonia salts were applied to wheat in the autumn 

 two-thirds of the nitrogen supplied was unrecovered 

 in the increase of the crops. From the application of 

 nitrate of soda in the spring more thap one half of the 



