486 ANNUAL REPORT OF THE Off. Doc. 



manure every year, or twenty-five tons for the five-year period. 

 This rate of manuring has caused the corn yield to rise steadily from 

 less than 39 bushels per acre for the first period, to more than 50 

 bushels for the third under rotative cropping, whereas the corn under 

 continuous culture has fallen from 43 to 34| bushels during the same 

 period despite the fact that the plot growing corn continuously re- 

 ceives more than three times as much manure every five years as the 

 corresponding plot in the rotation received for all the crops grown 

 during the same period. 



In the rotative cropping the oats crop is not directly manured, re- 

 ceiving only that left by the preceding corn crop — and, so far as 

 I am aware, all our experiments agree in showing that the crop 

 which is directly manured or fertilized receives the major portion 

 of the benefit from the treatment — hence the comparison in this case 

 should be made with Plot 18 in the rotative cropping, which receives 

 eight tons of manure each on corn and wheat, or sixteen tons every 

 five years, against the twenty-five tons applied directly to the oats 

 continuously during the same period. This secondary effect on the 

 oats, of manure applied to the preceding corn crop is shown by the 

 results to be even greater than is the direct eftect of the larger 

 quantity applied directly to the oats as we do in continuous culture. 

 The manured wheat shows a little larger yield in the continuous 

 than in the rotative cropping during the first period. At the end of 

 the second period the wheat in the rotation was slightly ahead of 

 the continuous, while at the close of the third period the yield of the 

 continuous wheat was little more than half that in the rotation. 



It thus appears that not only has there been a much greater de- 

 crease in the unfertilized yield under the continuous than under the 

 rotative cropping, but that the efi'ect of fertilizers and manure has 

 been much less on the crops grown continuously than on those grown 

 in rotation. 



It has not been uncommon during the progress of our fertility work 



«t the Ohio Station to frequently have grave doubts expressed as to 



the applicability of our plot methods to practical farm operations 



where fields several acres in extent are cultivated. In order to 



demonstrate that the plot methods were as entirely applicable to 



large as to small areas, we began putting into practice on a 40-acre 



field some of the lessons we have learned from our plot work. This 



forty-acre tract is divided into four sections of ten acres each on which 



is practiced a four-year rotation of corn, oats, wheat and clover. 



For the first ten years after the establishment of the Experiment 



Station in its present location our practice on this field was to top 



dress the ground for wheat in the fall, with ten tons of barnyard 



manure, the other crops following without any further fertilization. 



Seven years ago we adopted a different plan and began putting into 



practice some of the lessons above referred to. This consisted in 



applying ten tons of phosphated manure per acre to the corn ground 



in the fall, at a cost for raw rock phosphate used of |1.60. After 



the ground was plowed in the spring we applied one ton of lime per 



acre, costing |G.OO. In the fall the wheat ground received a dressing 



of 400 pounds per acre of fertilizer analyzing 4 per cent, ammonia, 



16 per cent, phosphoric acid and 5 per cent, potash, all costing $6.40, 



making a total cost of |14.00 per acre for the entire rotation. 



In comparing the results of the two methods we find that for the 

 first ten years before the change of plan the average yield per acre 



