20 BULLETIN "E.' ? 



rate of 79.311 Ibs. per ton; for 10 tons the increase was 66.740 

 Ibs. per ton; and for 15 tons it was at the rate of 53.636 Ibs. 

 per ton. There has, therefore, been a relatively higher effi- 

 ciency where the smaller amounts of manure were added. 



INFLUENCE OF FARM YARD MANURE ON THE WATER-SOLUBLE 

 SALTS OF SOILS. 



There is given in Bulletin "C,"* p. 81, a tabular statement of 

 the amounts of water-soluble salts recovered from 8 soil types, 

 as an average of determinations made on 6 different dates, 

 together with the differences between the total salts recovered 

 from each of the fertilized sub-plots and from the sub-plots not 

 fertilized. There is presented here a statement of the influ- 

 ence of the stable manure upon the amounts of each ingredient 

 recovered from the soil under field conditions. 



EFFECT OF 5, 10, AND 15 TONS OF MANURE UPON THE WATER- 

 SOLUBLE SALTS OF FIELD SOILS. 



The observations here presented cover a study, under field 

 conditions, from the time of applying the stable manure to the 

 soil the last of April until near the end of June, a period of 

 about 60 days, during which time samples were collected on 

 six dates. The manure had been very carefully and uniformly 

 spread over the surface of the fields and was plowed under to 

 a depth of 6 to 8 inches. The soil samples, in all cases, were 

 composites of four cores, one from each of the four repeated 

 sub-plots, and extended through the entire surface foot. 



In the next table there are given the percentage differences 

 in the amounts of each ingredient determined, using the 

 amounts recovered from the umnan.ured soil as bases and call- 

 ing these 100. 



Bureau of Soils. "C," Relation of Crop Yields to the Amounts of Water-solu- 

 ble Plant Food Materials. Recovered from Soils. 



