40 The Bulletin 



potash; for corn at the rate o£ 300 pounds per acre of a mixture con- 

 taining 7 per cent available phosphoric acid, 3 per cent nitrogen and IV2 

 per cent potash ; and for cowpeas at rate of 300 pounds per acre of a 

 mixture containing 8 per cent available phosphoric acid, 1 per cent 

 nitrogen and 4 per cent potash. Lime was applied at the rate of 500 

 pounds rock or building lime, or 1,000 pounds slaked lime. The ferti- 

 lizer applications in the tables, in addition to being represented in terms 

 of acid phosphate, dried blood, and manure salt, are also expressed in 

 terms of the symbols N, P, K, and L, which have the following signifi- 

 cance : 



N equals: for cotton, at rate of 10 pounds nitrogen per acre, or 77 pounds 

 of 13 per cent blood; for corn, 9 pounds per acre, or 69.2 pounds of 13 

 per cent blood; and for cowpeas, 3 pounds per acre, or 23 pounds 13 per 

 cent blood. 



P equals: for cotton, at rate of 28 pounds phosphoric acid per acre, or 175 

 pounds of 16 per cent acid phosphate; for corn, 21 pounds per acre, or 131 

 pounds of 16 per cent acid phosphate; and for cowpeas, 24 pounds per 

 acre, or 150 pounds 16 per cent acid phosphate. 



K equals: for cotton, at rate of 10 pounds potash per acre, or 50 pounds 20 

 per cent manure salt; for corn, 4.5 pounds per acre, or 22.5 pounds 20 per 

 cent manure salt; and for cowpeas, 12 pounds per acre, or 60 pounds 20 

 per cent manure salt or its equivalent of some other potash salt. 



L equals: for all the crops, lime at the rate of 500 pounds rock or 1,000 

 pounds slaked lime per acre. 



The following prices have been used in all the experiments in figuring 

 the cost and the value of crops : 



Acid phosphate, 16 per cent, $14.00 per ton. 



Dried blood, 13 per cent, $60.00 per ton. 



Manure salt, 20 per cent, $20.00 per ton. 



Rock lime, $10.00 per ton. 



Cowpea hay, $18.00 per ton. 



Oat and vetch hay, $18.00 per ton. 



Red clover hay, $18.00 per ton. 



Wheat straw, $6.00 per ton. 



Corn stover, $10.00 per ton. 



Corn, 80 cents per bushel. 



Cowpeas, $1.75 per bushel. 



Wheat, $1.00 per bushel. 



Seed cotton, 4.5 cents per pound. 



FERTILIZERS USED ON SOIL TYPE FIELDS. 



The fertilizing materials used on the Monroe, Gastonia, the two 

 Charlotte fields, and on Field E of the Iredell Test Farm as carriers of 

 the different elements of plant food were as follows : 



Dried blood for nitrogen. 

 Acid phosphate for phosphoric acid. 

 Potassium sulphate for potash. 

 Rock lime for lime. 



