This 4,000 pounds of cured hay will be made up of the fo 

 lowing : 



Lbs. 



Water, * 500 



Albuminoids, 304 



Carbo-hydrates, 2,960 



Fat, 56 



Ash, 180 



4,000 



The ash is made up of the following : 



Lbs. 



Phosphoric acid, 1 7 



Potash, 77 



Soda, 



Lime, • 20 



Silica, 5314: 



Magnesia, 10^ 



2% 



180 



This crop of hay would be made up of elements taken from 

 the air and from water, , ii>77S 



Elements taken from the soil, including nitrogen, 225 



12,000 



The deficimt plant food, or that which must be attended to 

 by the farmer, amounts to one hundred and thirty-nine pounds, 

 made up as follows : nitrogen, forty-five pounds ; phosphoric 

 acid, seventeen pounds, potash, seventy-seven pounds. 



Is it necessary to provide for all of the nitrogen, phosphoric 

 acid and potash, or will the soil furnish a part of these ? 



It is a well-known fact, that all soils fit for tillage are capa- 

 ble of producing small crops continuously. Old fields will pro- 

 duce in the vicinity of half a ton per acre of the so-called " June 

 grass," or "■ white-top," year after year. Such a crop takes from 

 the soil plant food, and when once the crop has reached the 

 lowest limit in its yield and continues year after year practically 

 the same, the plant food contained in this minimum crop repre- 

 sents the natural capacity of that particular soil to provide nitro- 

 gen, phosphoric acid and potash. Just what this natural capac- 

 ity amounts to may be illustrated by comparatively definite fig- 



7 



