34 



which can be produced on the farm. Town dung, however, has for a 

 great many years formed a favourite manure with hop farmers. This, 

 although it contains also a good deal of phosphates, may essentially be 

 regarded as a nitrogenous organic manure. Wool waste, or shoddy, 

 containing 5 or 6 per cent, of nitrogen, is sometimes used by hop 

 growers to the extent of as much as two tons per acre, while fish 

 .guano, containing about 8 per cent, of nitrogen, is often used to the 

 extent of a ton per acre, as is also rape dust. Slowly acting 

 manures like hoofs and horns containing about 14 per cent. 

 of nitrogen are also applied by the ton. Peruvian guano of the 

 old-fashioned type, essentially rich in ammonia, and forming a 

 "very readily available nitrogenous manure, was also a favourite appli- 

 cation for hops, and such limited quantities of rich guano, both 

 Peruvian and African, as are still imported, are largely used in the 

 hop districts. 



In more recent years sulphate of ammonia and nitrate of soda, 

 which differ from organic manures in being much more rapidly avail- 

 able, have been coming into use for hop growing as adjuncts to the 

 more slowly acting manures, over which they present, by their more 

 rapid availability, certain advantages. 



Manures in which the nitrogen exists in the form of animal or 

 vegetable matter have to become decomposed before they can be of 

 any use to the crop, their nitrogen being converted first into the form 

 of ammonia, which again has to undergo natural conversion into 

 nitrates within the body of the soil before it becomes available as a 

 plant food. In these respects organic manures resemble the natural 

 organic matters of the soil. 



These successive processes of fermentation and nitrification 

 especially the latter only take place during fairly warm weather, and 

 when the hop plant begins its growth the nitrogen it takes up may be 

 said to be mainly derived less from the organic manures which have 

 been applied during the winter and spring than from the unused 

 nitrates formed in the soil during the previous summer and autumn by 

 the decomposition and nitrification of manure applied earlier. It is 

 not until the bine is well advanced in growth that the nitrogenous 



