1907.] PUBLIC DOCUMENT — No. 33. 43 



accounted for only as a result of the fre(iuent introduction 

 of clover in the rotation. 



It will be noticed that on plots 1 and 3 phosphoric acid 

 has been applied in the fertilizers used in quantity on the 

 average more than five times greater than the quantity re- 

 moved. Even on plots 2 and 4 phosphoric acid has been sup- 

 plied in quantity practically double that removed. 



Potash on one of the plots (1 and 3) has been supplied in 

 slightly larger quantity than removed, while on the other 

 plot the quantity removed is slightly in excess of the quan- 

 tity supplied. 



On the average, the condition of the soil as regards this 

 element on plots 1 and 3 cannot be materially different from 

 what it was at the beginning of the experiment. On plots 

 2 and 4, on the other hand, potash has been supplied in quan- 

 tity a little more than double that removed. 



V. — South Corn Acee. — Manure Alone v. Manure 



AND Potash. 



The object in view in this experiment is to compare the 

 crop-producing capacity of manure alone applied in fairly 

 liberal amounts with a combination of a lesser amount of 

 manure and a moderate quantity of a potash salt. An acre 

 of land is used in the experiment. It is divided into four 

 plots, of one-quarter acre each. Two of the plots (1 and 3) 

 have received applications of manure only ; the other two 

 plots (2 and 4) have been fertilized by applications of lesser 

 amounts of manure, together with a potash salt. 



This experiment was begun in 1891. The crop for the first 

 six years was corn. Corn was raised also in 1899 and 1900, 

 and in 1903 and 1904. The field has been put into mixed 

 grass and clover three times, being seeded in the summer 

 preceding the first year of cutting in the corn crop. Each 

 time that the land has been seeded it has been cut twice 

 annually for two years. The sod has then been broken in 

 the fall for the corn crop of the following year. The years 

 when the field has been in momng are 1898 and 1899, 1901 

 and 1902, and 1905 and 1906. 



Manure has been applied to plots 1 and 3 every year, at 



