404 ANNUAL REPORT OP THE Off. Doc. 



corn and wheat only, was receiving only one-foiirth this quantity of 

 nitrogen, half as much phosphorous, and two-thirds as much potas- 

 sium, and yet at the end of the first five year rotation, the total in- 

 crease on Plot 14 had been greater than that on the manured plot. 



This outcome was altogether contrary to our expectations, for we 

 shared in the common opinion that the chemical elements in manure 

 should be as effective, pound for pound, as those in fertilizers, and 

 that manure should possess a further advantage in its physical effect 

 upon the soil. 



We therefore undertook a more thorough study of manure, by 

 starting a series of experiments in which manure taken directly 

 from the stable to the field and spread at once is compared with the 

 manure which is thrown into the barnyard and allowed to lie there 

 for several months before it goes to the field. This work has been 

 continued for eighteen years, and the outcome has been that the 

 manure which has gone directly from the stable to the field has pro- 

 duced increase greater by twenty per cent, as an average of five 

 duplicate comparisons, than that which passed through the barn- 

 yard. 



These field experiments have, therefore, fully confirmed the chem- 

 ists verdict respecting the loss which manure suffers through ex- 

 posure to the weather; one chemical analysis having shown a loss 

 of fourteen per cent, of the phosphorus, with still larger losses of 

 nitrogen and potassium during the short period when the manure 

 was exposed. 



That the losses are very much greater when the manure lies in the 

 barnyard until August, instead of only until April, cannot be 

 doubted. But the loss which manure suffers from exposure to the 

 weather is only part of the loss which is experienced under the ordi- 

 nary farm practice. Attention has already been called to the rela- 

 tively large draft upon the soil phosphorous in the growth of young 

 animals and the production of milk. In grain farming there is a 

 similar loss of this element; for as the plant matures about three- 

 fourths of its phosphorus is transferred to the grain and whether 

 the grain is sold or is fed, this phosphorus, or a considerable part of 

 it, is carried off the farm. The result is that a relative deficiency of 

 phosphorus is soon show^n in the soil, nnd if enough manure is used 

 to make up this deficiency, there will be a considerable waste of 

 nitrogen and potash. 



For these reasons the experiments in which fresh manure and 

 yard manure were contrasted were so planned as to show the efifect 

 of reinforcing the manure with phosphorus, by mixing it with acid 

 phosphate, or with the crude phosphate rock from which acid phos- 

 phate is made, these materials being added at the rate of forty 

 pounds per ton of manure, the crude rock being ground into the fine 

 powder called floats. 



