28 HATCH EXPERIMENT STATION. [Jan. 



It will be noticed that the average rate of yield on all 

 plots to which potash salts are applied, with the exception 

 of those where kainite is the source of potash, is greater 

 than on the no-potash plots. The average yield on the 

 kainite, on the other hand, is much below the average on the 

 no-potash plots. Examination of the longer table shows 

 that this inferiorit}^ of kainite was constant for each of the 

 five plots. Such examination also shows that the variation 

 in relative standing of the plots where each of the different 

 potash salts was used is fairly constant for each. The most 

 marked exception to this rule is found in the case of plots 

 30, 36 and 37, where the yields are lower than on other 

 plots receiving the same potash salts. This inferiority on 

 these plots appears to have been due to the fact that the 

 stand of plants in them was too thin. A count indicates 

 that the average num])er of plants in a row in this field is 

 alwut 120 ; in Plot 30 it was about 1)5 ; in plots 3() and 37 

 about 45. The potash salt giving the highest yield in this 

 experiment is the carbonate, followed closely by the high- 

 grade sulfate and silicate. The potash salts, other than 

 kainite, containing chlorine (low-grade sulfate and umriate), 

 give yields considerably lower. As neither the carbonate 

 nor the silicate of potash is commonly found in our markets, 

 these having; been manufactured in the first instance as ferti- 

 lizers for tobacco, the practical lesson to be drawn from the 

 experiment is that for the soy bean it is much safer to depend 

 upon the high-grade sulfate as a source of the needed potash 

 than to use any of the potash salts containing chlorine. 

 Neither the carbonate nor the silicate, even if available, 

 would Ix! preferable to the high-grade sulfate, as the cost 

 per unit of potash is much greater than with sulfate. The 

 result of the past season is in agreement with results obtained 

 with this crop in a considerable numlier of earlier experi- 

 ments, and it seems impossible to doubt the validity of the 

 conclusion above stated. The advice, therefore, is most 

 strongly given, that, on all soils at least with good retentive 

 qualities and moisture, the sulfate of potash should generally 

 be preferred to muriate or kainite, not only for soy beans, but 

 for clovers and with little doubt for all other legumes as Avell. 



