1916.] PUBLIC DOCUMENT — No. 31. 21a 



phosphate nor the muriate of potash in connection with the 

 manure has been distinctly beneficial, and that in this combina- 

 tion, as when used alone in connection with manure, nitrate at 

 the rate of about 450 pounds per acre appears to be as large 

 an amount as it is profitable to use on the Concord soil. 



8. General Conclusion. — Without exception, the combination 

 of chemicals used in these experiments has given as large annual 

 yields as the combination of manure at the rate of 20,000 

 pounds per acre and chemicals, a result which seems somewhat 

 surprising. The largest yield obtained on any plot during the 

 last few years has been on the one annually top-dressed in 

 early spring with chemicals at the following rates per acre : — 



Nitrate of soda, 450 



Acid phosphate, 450 



Muriate of potash, . * 262 



So far as this series of experiments goes, therefore, and it 

 should be remembered that it has continued nine years, we are 

 apparently justified in concluding that this application of chem- 

 icals fairly satisfies the requirements of the crop. It is un- 

 doubtedly important in this connection to recall the fact that 

 the land on which these experiments are located had not been 

 cultivated for a considerable number of years previous to its 

 selection for this work. In preparation for these experiments, 

 the land was cleared of brush and trees and plowed in the 

 spring of 1906. It then received an application of fertilizers at 

 the following rates per acre: — 



The lime w^as applied by itself, the other materials were 

 mixed, evenly spread and harrowed in. The field was thor- 

 oughly prepared in the spring of 1906 and sown to buckwheat. 

 The buckwheat made a heavy growth and was plowed under 

 when fully grown. The field was then harrowed and sown to 



