118 APPLICATION* OF MANURE. 



thrives best in a healthy soil, incumbent on a pervious subsoil, and at 

 a high altitude ; Larch in loam, with a dry subsoil, in a high situa- 

 tion, and on sloping banks ; Spruce and silver firs, in soft loam or 

 peaty soil, in a low moist situation, but they will also grow in a dry 

 soil, and in a pretty high altitude; Oak in any soil and situation under 

 800 feet above the level of the sea, but it thrives best in clayey loam, 

 on a rather retentive subsoil, and on gently sloping ground ; Ash and 

 Elm, on a gravelly loam, on gravel or sand, at an altitude under 

 500 feet above the level of the sea; Sycamore, at 100 feet higher 

 than the ash or elm, and in a more retentive soil and subsoil ; Beech, 

 on a dry gravelly soil, and in a rather high situation, but it is often 

 luxuriant on strong retentive clay, and in a low damp situation. 



APPLICATION OF MANURE. 



240. If the soil does not contain the ingredients required for a 

 crop, they must be added in the form of manure. The principle of 

 manuring is to supply what the plant cannot obtain from the soil, and 

 to render certain matters already in the soil available for nutrition. 

 In order that this may be properly practised, there must be an 

 analysis of the soil, of the plant, and of the manure. Hence the im- 

 portance of agricultural chemistry to the farmer. 



Various kinds of Manure. 



241. Natural Manures, as farm-yard dung, are more valuable than 

 simple manures; inasmuch as the former furnish all the substances 

 required for the growth of plants, while the latter only supply a 

 particular ingredient. The plant itself, in a soluble state, would be 

 the best manure. In ordinary farm-yard manure, the straw is again 

 made available for the purpose of the plant. The whole crop of wheat 

 and oats, however, cannot be returned to the soil, as part must be 

 retained for food. A substitute, therefore, must be found for the 

 portion thus taken away. This contains both azotised and unazotised 

 matters, the former consisting of proteine compounds which supply 

 nitrogen for the muscular tissue of man and animals ; the latter of 

 starchy, mucilaginous and saccharine matters, which furnish carbon as 

 a material for respiration and fat. The object of manuring is chiefly 

 to increase the former, and hence those manures are most valuable 

 which contain soluble nitrogenous compounds. 



242. The value of manures is often estimated by the quantity of 

 gluten which is produced by their application. Hermbstaedt sowed 

 equal quantities of the same wheat on equal plots of the same ground, 

 and manured them with equal weights of different manures, and from 



