MAM i;i:s AND NITRIFICATION 



lmrii- i' 1. 1 ami lime, ami. although Hindi more potash than phosphoric 



and is curried off in your crop, potash i^ lut seldom added." So again, 

 writer^ ha\e liowii, and most conclusively, that if the soil docs 

 s enough lime, hone and other expensive manures may be 

 than useless. Voelcker (Imjjrov. Ind. Agri., 1893, 270), for ex- 

 ample, some years ago observed that the differences of practice occur 

 in the manner of applying manures, some planters preferring to throw 

 manure broadcast and to fork it in, others thinking it better to dig a 

 trench round the bush, about a foot or a foot and a half from the stem, 

 and to put back the soil mixed with whatever manure it is intended to 

 apply. " Manures such as bones, oilcakes, etc., are too generally used, 

 ise they have always been used, and because there is a general belief 

 in their utility, but it is more than probable that in some cases large sums 

 needlessly expended on them, while in others lack of lime, potash, 

 >r other soil-constituent may be responsible for a diminishing yield." 



The manures and the methods of applying them to one plantation 

 are not always applicable to another, so that no general rule can be laid 

 low n, and the indications afforded by the soil itself must be closely fol- 

 >\ved. In some parts of the coffee area, fish manure is much appreciated 



a crop fertiliser, cow-dung being viewed as strengthening the wood. 

 lixed bone and fish manure produce an abnormally heavy crop. Oil- 

 cake (poonac) is believed to strengthen the leaves against blight. [C/. 

 Voelcker, I.e. 104-5.] 



The season for applying manure is also a subject of much difference of 

 opinion, but is possibly best solved by a careful study of the particular 

 manure that it is contemplated to be given. Stem and leaf-forming 

 manure should naturally be given just after the crop has been gathered ; 

 those supposed to increase the yield would, on the other hand, best be 

 supplied just before the flowers appear, say in February and March. So 

 again, bone and other manures that take some time to decompose require 

 to be given early and soluble manures much later. Many writers seem, 

 however, to condemn immediate or chemical manures and regard these 

 as possessing few, if any, advantages for coffee. 



Assimilation of Free Nitrogen. So much has been said of the advan- 

 of growing (as a sort of rotation) leguminous crops along with coffee, 

 that a volume might be written on that topic alone. The subject is by 

 no means new nor confined in its applicability to coffee. A rotation of 

 clover with grain crops became a principle of all early European agriculture, 

 long before the correct explanation of that system had been discovered. 

 Its application to coffee has been urged by all writers, more especially 

 by Mr. B. Nelson. The use of leguminous shade-trees such as the sau 

 of the Assam tea planters (Albizzin sfij>u/<ita) and the Eri/thrimi 

 lit/iitsfn'i-nni of coffee planters are good examples of both shade and 

 nitrogen assimilation. (See below the para, on Shade-trees.) [Cf. Pests 

 and Blights of the Tea Plant, 136-47.] 



Nitrification. Allied to the study of free nitrogen, though perfectly 

 distinct, are the methods by which the combined nitrogen of the soil or 

 of manures is prepared for plant use and the processes or vehicles of its 

 transmission into the roots. This is defined as the nitrification of the soil. 

 Nitrogenous matter is oxidised and the nitrogen developed into a nitrate 

 chiefly of lime or of potash. Until quite recently it was believed to be a 

 simple chemical process. But it has been ascertained to be a oonsequeiv. e 



379 



COFFEA 

 ARABICA 



Cultivation 



Bow 



Oilcake 

 (1'oonac). 



Fish. 



Season for 



M.mun-s. 



Chemical 

 Manures. 



Free 

 Nitrogen. 



Leguminous 

 Crops. 



Nitrifica- 

 tion of the 

 Soil. 



