SOILS FKRTTLIZERS. 715 



The effect of soils on the solubility of potassium, F. W. Morse and B. E. 

 CiRRY (\civ Iltinipsliirc Sta. Rpts. n)07-S, pp. 293-2!)!). — Studies of the 

 changes in solubility of potash when addeil in the form of chlorid tt» clay and 

 sandy clay soil and sandy loam aro re])orted. 



It was found that the soils (luicUly and completely fixed the soluble potash 

 and converted it into insoluble forms. "The rate at which these changes take 

 place has been shown to be very rapid under favorable conditions; also it has 

 been demonstrated that large quantities of potassium may be acted upon." 

 This is considered " an argument in favor of light and numerous applications of 

 potassium for either chemical or mechanical effects." 



Some notes on the solubility of potassium of soils and soil minerals, F. W. 

 MoKSK and B. E. Curry {New Ilainiishirc Stu. Rpts. J907-8, pp. 291-310, fig. 

 /).— This paper reports the results of studies of the solubility of the potash 

 of feldspars when acted upon by lime, gypsum, sodium nitrate, ammonium 

 sulphate, sodium carbonate, and sodium ]iliosphate. and of soil when acted 

 uiion by lime and gypsum. 



The conclusions reached were that — 



'■ In general, the amount of water-soluble salts in a given soil is dependent 

 on the amount of soil moisture, and the time during which the soil and mois- 

 ture have been in contact, providing, of course, that the time has not been 

 sufficient to establish equilibrium. Equilibrium having been established, the 

 amount of solute depends on the amount of moisture. 



"The rate at which the feldspar dissolves is fairly rapid until ajiproximate 

 equilibrium is established. 



" The rate at which the soil minerals dissolve decreases as equilibrium is 

 approached. 



" The effect of these solvents is to increase the amount of soluble potassium 

 in the feldspars. 



" Time produces the most pronounced results. 



" These solvents do not increase the amount of water-soluble potassium in 

 soils. 



"We have not been able to replace the potassium in zeolytes (apophylite), 

 by stirring the ground mineral with lime. 



" The results are different, depending on whether soil or mineral is subjected 

 to the action of these solvents. The difference is due to the presence of clay 

 in the soils. 



" The action of the clay is not dependent on temperature. 



" The addition of clay to a solution of CaO depresses the solubility of the 

 t'aO. This action, apparently, is analogous to the depression of the solubility 

 of potassium. 



" From a laboratory point of view, the effects of lime on a soil are more 

 mechanical than chemical. The mechanical effects are easily noted. The 

 chemical effects can not be followed. 



" In a i)ractical way the mechanical effects due to the action of lime may or 

 may not produce greater crop yields. At present we can not make predictions 

 either way with any great certainty. 



" Neither field nor laboratory work has been able to establish any relation 

 between applications of lime to soil and the amount of water-soluble potassium 

 in the soil moisture." 



The distribution of potassium in cultivated soils ( Engrain, 2.'i {1909), No. 15, 

 p. .',09; ahH. in Chem. Ahs., 3 {1909), No. 18, p. 2192).— It is stated that the 

 greater part of the i»otash in soils is in the form of double silicate of potash and 

 aluminum, which is not readily assimilated by plants. It is for this reason 



