BUBEAU OF AoEIOULTtTfiE. , 161 



Let, it be understood also that this soil was extremely de- 

 ficient in organic matter in the beginning of the experi- 

 ment. The ground was badly worn and had not for many 

 years produced a crop that paid for the labor put upon 

 it. In 1908 it made less than 3% bushels of wheat per 

 acre with the use of 200 lbs. per acre of a 2-8-2 fertilizer, 

 the year being favorable for wheat. 



Plot No. 5 is not to be considered a check plot. It 

 is a low piece of ground that has for many years been 

 receiving washings from the ground around it, and is 

 naturally more productive than the other plots. It is in- 

 cluded to show that the poorer ground by proper treat- 

 ment can be made to surpass it in fertility. There was 

 a slight increase in natural fertility from plots 1 to 4, 

 inclusive, the greatest variation being in plot 1. There 

 was not a great deal of difference in plots 2, 3, 4 and 6. 



In calculating values corn is rated at 60 cents per 

 bushel, wheat at 90 cenis, oats at 40 cents, and all hay 

 at $12 per ton. Stover and straw are not included in the 

 valuations. Stable manure was returned to the soil 

 in the equivalent of the crops each treatment produced. 

 In all other particulars the plots were handled in a uni- 

 form manner, including cultivation, catch crops and 

 cover crops. 



While there is seemingly a slight increase in yields 

 in some cases where potash* was used, yet it is not suffi- 

 cient to justify the use of it. 



The argument is sometimes advanced that acid phos- 

 phate sets free potassium in the soil, thus showing the 

 need of adding potash. If acid phosphate does this, as 

 it very likely does, it certainly is an argument against 

 the investment of money in potash fertilizers when acid 

 phosphate is used. 



•The seemingly interchangeable use of the terms "potassium" and 

 "potash" may appear awkward, and may confuse persons without chemical 

 training-. The soils laboratory of the Experiment Station uses "potassium" 

 in reporting soil analysis, while the fertilizer laboratory uses the term 

 "potash." In this bulletin we have used "potassium" in discussing It as 

 an element of plant food in the soil and crop, while "potash" is used in 

 referring to fertilizers and materials furnishing the element "pottassium." 

 In like manner "phosphates ' is used on the one hand and "phosphoric acid" 

 and "phosphates" on the other. 



agr. — 6 



