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CHAPTER V. 



MANUKES. 



History of using manures. First manure, animal and vegetable 

 refuse. A farm in ancient times returned to the field what 

 was taken away from it. A decrease in the outturn first 

 perceptible when the farmer exported his produce. Rota- 

 tion of crops forced upon the farmer by the declining 

 fertility of the soil. Fallowing the next step. The soil 

 ceases to be remunerative and requires rest. The rational 

 solution of the difficulty. The importation of manure as 

 an equivalent for the exportation of produce. Artificial 

 manures ; their use and abuse. Different manures for 

 different crops and soils. Special manures ; their nature, 

 and relation to the soil. The disappointment which must 

 follow their indiscriminate use. Monetary waste in 

 supplying phosphoric acid to a soil already containing it 

 in abundance. An intimate knowledge of a soil necessary 

 in order to obtain the highest results by the smallest outlay. 

 Liebig on manures in their relation to crops and soils. 

 The Minimum Theory. An analysis necessary to point 

 out the Minimum. 



AN instinctive though vague comprehension of 

 the requirements of plants induced cultivators 

 from the earliest times to spread refuse, animal 

 and vegetable, over their fields, in order to main- 

 tain their fertility ; and this procedure we call 

 manuring . 



Reverting to the farming of those times, we 

 find that the description of manure first employed 

 was naturally all the animal and vegetable 



