Variation in Value and its Causes 



more than anything else, and receiving substantial 

 food, emit far richer excrements. 



Dairy stock will not give such a rich manure, be- 

 cause their milk contains a great deal of phosphoric 

 acid and lime, while draught horses and oxen, having 

 no need of further development, but chiefly assimi- 

 lating the carbonic hydrates and disassimilating the 

 other substances, also give a rich manure. 



Farmyard manure differs, further, in accordance 

 with the kind of animal that produces it, and in this 

 respect it is distinguished as " hot " and " cold " 

 manure. That of sheep, for example, is very hot, that 

 of the horse hot. These contain relatively little 

 water and much nitrogenous matter. They are called 

 " hot" manures because they ferment easily and emit 

 much vapour, ripening very quickly, so that their 

 nitrogen is soon in an assimilable form at the dis- 

 posal of the plants. These manures act rapidly, 

 but their action is not very prolonged. They are 

 specially suitable for cold soils in which they hasten 

 the commencement of vegetation. In the neighbour- 

 hood of to\vns they are chiefly used by market 

 gardeners to make hotbeds in which the temperature 

 has to rise very rapidly and very high, but in which 

 the action cannot be very prolonged because after 

 a short time the temperature falls. 



Cattle manure is cold, that of pigs very cold, 

 both containing a great deal of water. These 

 manures ferment and also ripen very slowly. They 

 are best for light lands and those lacking in humus, 

 and if their action is very slow it is also very pro- 

 longed. They are of no use for hotbeds because 

 they do not develop a high temperature, but, on the 



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