160 



acter should be expected from those given in the previous sec- 

 tion. Moreover, the solution has been made stronger as well as 

 being of a different chemical nature. 



It will be seen that potash has been absorbed in larger 

 amounts in every case, as was to be expected from the larger 

 amount used in the solution; and the soils giving the larger 

 yields have, as a group, absorbed the largest amounts, although 

 they are known, as demonstrated by the data of Bulletin B, to 

 contain much more potash in the form capable of being recov- 

 ered by repeated washing. In the next table there are placed the 

 amounts of potash recovered by 11-times washing, together with 

 the amounts absorbed here, and the sums taken as indicating, 

 possibly, the lower limit of amounts of potash these soils are able 

 to retain. At any rate, the sums will indicate the probable 

 amounts of potash these samples did contain after having re- 

 ceived this treatment. 



Probable amounts of potash contained by 8 soil types after treat- 

 ment with a solution of guano to which potassium nitrate was 

 added. 



These Janesville samples, after absorption, are therefore car- 

 rying nearly 500 parts per million of potash; the Lancaster sam- 

 ples nearly 400 parts per million ; and the other four soils less 

 than 350 parts per million, as an average. 



The four Northern/ soils have retained an average of 



439.38 329.24 & 110.4 parts per million 



more potash, which, on the basis of 3,000,000 Ibs. per acre-foot, 

 represents 330 Ibs. of what may be expected to be available pot- 

 ash per acre more than the Southern soils carry under these 

 conditions. 



