MANURES. 351 



All tables showing the comparative effect of different 

 manures are of very problematical value. There are so 

 many circumstances and conditions of soil, climate, expo- 

 sure, moisture, previous treatment of the land, &c., &c. 

 all of which affect, more or less strongly, the amount of the 

 crop that it is never possible (in the light of our still 

 imperfect knowledge concerning the growth of plants, and 

 their relations to the soil) to decide how far any increase or 

 decrease may be due to the manure used, and how far to 

 other causes. 



TABLE, showing the effect produced upon the quantity of the 

 crop ly equal quantities of different manures applied to 

 the same soil) sown with an equal quantity of the same 



seed. 



Return in bushels from each bushel of seed. 

 Manure applied. Wheat. Barlej'. Oats. Rye. 



Blood 14 16 12 14 



Night-soil 13 14 13J 



Sheep-dung 12 16 14 13 



Horse-dung 10 13 14 11 



Pigeon-dung 10 12 9 



Cow-dung 7 11 16 9 



Vegetable manure 3 7 13 6 



Without manure '... 4 5 4 



Moisture absorbed by different manures. 



1000 parts horse-dung, dried in a temperature of 100 

 Fahrenheit, absorbed by exposure to the air at a 

 temperature of 62 Fahrenheit, moisture, parts 145 



1000 parts cow-dung, under same circumstances, u 130 



