FARM MANURE 



545 



TABLE in. COMPOSITION OF PULVERIZED DRIED MANURES 

 Pounds per Ton 



of ordinary crops grown in a good rotation, and figured at average 

 prices for the corn belt. These data give the manure a value of 

 $1.65 per ton where 12 tons per acre are used, $1.32 where 16 tons 

 are applied, and $1.14 where 20 tons are applied, for each four-year 

 rotation, corresponding to annual applications of 3, 4, and 5 tons 

 per acre, respectively. Since the lightest application appears to 

 maintain the (moderate) productive power of the land for the 

 second 1 2-year period as compared with the average of the first 

 12 years, it seems that $1.65 per ton may be regarded as the full 

 agricultural value of the manure for use in permanent systems. 



Of course the manure might be worth less on better land and 

 more on poorer land; and with different crops (as cotton, fruit, 

 potatoes, etc.) or with different prices, its value would be 

 different. 



If we refer our comparison to the unfertilized land during the 12- 

 year periods, the 12 tons of manure were worth $1.14 a ton during 

 the first 12 years and $2. 14 a ton as an average of the second period, 

 and during a third 1 2-year period the value will no doubt be still 

 greater, measured against the still further depleted, untreated land. 

 In- the Ohio experiments, with the five-year rotation (Table 82) 

 8 tons of manure were worth $2.18 a ton and 16 tons were worth 

 $1.69 a ton; while in the three- year rotation the 8 tons of manure 

 applied for potatoes were worth $3.63 per ton, with potatoes at 

 50 cents a bushel. 



In the potato experiments on Hoos field at Rothamsted, 94.2 



