58* N. H. AGR. EXPERIMENT STATION. [Bulletin 142 



In order to show how lime prevents the solution of iron and 

 aluminum, the following experiment was tried in the laboratory: 

 A clay soil was shaken with a solution of potassium chloride and 

 filtered. The filtrate contained large quantities of iron and 

 aluminum, but very little lime. To a second portion of the clay 

 a quantity of carbonate of lime was added, and the mixture 

 shaken with a new solution of potassium chloride and filtered. 

 This solution contained no iron or aluminum, but fairly large 

 amounts of lime. The carbonate of lime had prevented the 

 solution of iron and aluminum and in the process a considerable 

 quantity dissolved. This going into solution was a part of the 

 process because the carbonate of lime does not go into solution 

 in the absence of the chloride of potassium. The action of lime 

 and its effect on root growth will be discussed more at length 

 in a subsequent paper. 



SUMMARY. 



Summing up these observations we have found that: 

 First — The clay and clay loam soils carry large quantities of potash. 



Second — The potash in these soils is soluble enough to supply potash 

 for heavy crops of grass without artificial reinforcement. 



Third — Additional potash when supplied in commercial fertilizers does 

 not affect the yield or the composition of the grasses. 



Fourth — The amount of potash required for a grass crop is proportional 

 to the yield. 



Fifth — A comparison made between the amount of water soluble pot- 

 ash in these soils, the amount of potash in the crop, and the amount 

 of soil water required to produce the crop, shows that the addition 

 of potash fertilizers is not necessary. This relation stands for these 

 soils when large yields are produced by the addition of other fer- 

 tilizer. 



Sixth — It is shown that when lime reacts with feldspathic minerals the 

 potash dissolves. Also when clay is present, as in these soils, no 

 increased amount of soluble potash is produced. This is because 

 of the action of the clay on the solubility of potash. 



Seventh — A large part of the potash In fertilizers is changed to an in- 

 soluble condition soon after it is applied to the soils. 



Eighth — When the potash is rendered insoluble other bases go into 

 solution. Lime has decided effects on these by-products. 



* Bulletin 141 was incorrectly paged 245-280, and should have been paged 1-36. The 

 present bulletin is therefore paged 37-58. 



