1013. 



PUBLIC DOCUMENT — No. 31. 



25 



250 pounds per acre has been applied to each plot. The object 

 has been to supply annuall^y the same amount of actual potash 

 to each plot, and to study the eft'ects of the continued use of 

 these potash salts upon the same soil. The following table 

 shows the crops grown this }'ear and the rate of yield ])er acre 

 for each : — 



CoMrARISOX OF DiFFEKE.XT PoTASH SaLTS FOR FlELD CkOPS. 



Field G. 



The plan and object of this experiment is quoted from the 

 nineteenth annual report of the experiment station : — ■ 



This experiment is clesignecl to show the ultimate etTect upon the soil, 

 as well as the current effect upon the crops, of continuous use of differ- 

 ent potasli salts. We have under comparison kainit, high-STadc sulfate, 

 low-grade sulfate, muriate, nitrate, carbonate and silicate.' The field 

 includes forty plots, in five series of eight plots each. Each series in- 

 cludes a no-potash plot, as v.ell as the seven potash plots which have 

 been named. The experiment is therefore carried out each year in 

 quintuplicato. The area of each plot is one-fortieth of an acre. The 

 potash salts under comparison are used in quantities which will supply 

 annually actual potash at the rate of 16.i pounds per acre to each of 

 the plots. All plots are equally manured, and liberally, with matei;ials 

 furnishing nitrogen and phosphoric acid.- 



' Owing to our inability to obtain silicate of pot.ash feldspar was substituted in 1908, and 

 Las since been used on these plot^. 



2 The nitrogen and phosphoric acid are supplied by the following materials per acre: — 



Pounds. 



Nitrate of soda 250 



Tanl<age 270 



Acid phosphate 360 



