10 



when 8 tons of manure has been taken directly from the stable 

 to the field and spread on an acre of land in January, to be 

 plowed under in preparing the land for corn the following 

 April, it has increased the three crops — corn, wheat and 

 clover — by a value equivalent to an average of S3. 60 for each 

 ton of manure. When 40 pounds of gypsum has been mixed 

 with the ton of manure before spreading, the increase has been 

 worth $3.76, after taking out the cost of the treatment. When 

 kainit has been used instead of gypsum the net value of the 

 increase has been $4.04; when raw phosphate rock has been 

 used the net value has been $4.80; and when acid phosphate 

 has been used the net value has been $5.40, the reinforcing 

 materials being used at the rate of 40 pounds per ton of manure 

 in every case, and the cost of treatment being deducted. Corn 

 is valued in these estimates at 50 cents a bushel, wheat at $1 

 and hay at $10 a ton, no account being taken of stover or 

 straw. By this treatment the yield of corn has been raised to 

 an eighteen-year average of 66 bushels per acre, and that of 

 Avheat to 27 bushels. 



Parallel with these tests, on another series of plots, manure 

 has been used in the same quantity as weighed from the stall, 

 but it has been allowed to lie in flat piles in the barnyard, after 

 being weighed out in January and treated with the reinforcing 

 materials, until the land was ready for the plow in April, when 

 these lots were spread and plowed under. The outcome has 

 been an average loss of 74 cents on each ton of the exposed 

 manure as compared with that which went directly from the 

 stable to the field. 



The large effect of the phosphates used in the reinforcement 

 of the manure has no doubt been due to the hunger of this 

 soil for phosphorus and to the kind of crops grown. On a soil 

 used for crops requiring potassium more urgently than phos- 

 phorus it is to be expected that kainit would produce a rela- 

 tively larger eft'ect. 



In the Ohio station's tobacco-wheat-clover rotation, however, 

 fresh manure reinforced with acid phosphate has produced in- 

 crease to the net value of $7.45 per ton of manure, as against 

 $6.63 for untreated manure, this larger value per ton being due 

 to the high acre-value of tobacco as compared with the cereal 



