120 A YEAR IN AGRICULTURE 



of nitrogen. To replace the nitrogen carried away in a 60- 

 bushel crop of corn would require nine tons of manure or 

 two and a quarter tons of clover per acre. The important 

 thing is to use the facts concerning the amount of nitrogen 

 in manure and crops, and return enough to the soil to pro- 

 vide for the grain crops, having such yields as are desirable 

 or possible under permanent systems. The following facts 

 should help us to solve this problem: 



NITROGEN SUPPLIES AND REQUIREMENTS 



Manure and produce Nitrogen 



1 ton average manure 10 pounds 



1 ton clover hay 40 



1 ton alfalfa hay 50 " 



100 bu. corn. 100 " 



3 tons corn stalks 48 " 



100 bu. oats 66 " 



2% tons oat straw. 31 " 



50 bu. wheat 71 " 



2y 2 tons wheat straw 25 " 



ON LIVE-STOCK FARMS 



For the live-stock farmer I would suggest a five-field rota- 

 tion system besides the pasture land. Four of these fields 

 may be used for a four-year rotation of corn, oats, and 

 clover, while the fifth field grows alfalfa for perhaps five 

 years, after which the alfalfa field may be put into the 

 four-year rotation, and one of the other fields used for 

 alfalfa for another five-year period, and so on. If the manure 

 is saved with reasonable care, as many tons should be returned 

 to the soil as the number of tons of air-dry produce that are 



