330 STATE BOARD OF AGRICULTURE. 



EFFECTS OF HYiDROXIDES 



Soil investigators have known for a long time that soils neutralize soluble 

 hydroxides. This property of soils is generally considered due to hydrated 

 silica of ferro-alumino-silicates. In order to determine if fixation from 

 hj^droxides followed the same general order as fixation from neutral salts 

 the investigation was continued using KOH and Ca(0H)2. Results from 

 this work are given in Tables 7 and 8. 



The alkaline soils fixed more potassium from the KOH solution than the 

 acid soils of corresponding classes, except the alkaline clay loam, and more 

 calcium from the more concentracted solution of Ca(0H)2 except the alka- 

 line medium sand which contains applied CaCOs. The acid clay loam showed 

 the same characteristics as in case of the neutral salt treatments in that it 

 fixed more potassium and less calcium than the alkaline clay loam. Solutions 

 from the KOH and concentrated Ca(0H)2 treatments were alkaline to phenol- 

 phthalein showing an excess of hydroxide. Solutions from the less concen- 

 trated Ca(0H)2 treatments were acid to phenolphthalein and in this case 

 the magnitude of fixation in all the soils varied only slightly. Solutions from 

 the KOH treated soils were characterized by comparatively large quantities 

 of iron and aluminum (neglecting phosphorous) and Si02 but small quantities 

 of calcium. Potassium was fixed in large quantities but no equivalent liber- 

 ations were found in the solutions. Quantities of calcium found in the 

 solutions from KOH treatments were very much smaller than the solubility 

 factor for this element as Ca(0H)2. Evidently potassium was fixed from 

 KOH without exchange of calcium or magnesium and in addition the KOH 

 dissolved iron, aluminum and Si02 from the soils. 



That potassium fixed from KOH may be liberated again by neutral salts 

 and Ca(0H)2 treatments may be seen from the results presented in Table 8. 

 The soils used in this case were first treated with the KOH solution, washed 

 thoroughly with distilled water until the washings were neutral to litmus 

 paper and then again treated with the CaCl2 and Ca(0H)2 solutions in the 

 usual manner. The quantities of calcium fixed from CaCU and quantities 

 of potassium exchanged were closely equivalent, the equivalent factor being 

 0.512. Fixation of calcium from Ca(0H)2 and exchange of potassium were 

 proportional in the two soils studied, but not equivalent; a much greater 

 equivalent weight of calcium was fixed. 



Conclusions from the work on hydroxides are: (1) Potassium and calcium 

 were fixed from their hydroxides in large quantities by soils without equiva- 

 lent exchange of other elements. (2) The solubility effects of hydroxides on 

 soils were of relatively great magnitude. (3) All of the soils used fixed the 

 cations of the hydroxides. (4) A portion, at least, of the cations fixed from 

 the hydroxides was in an exchangeable condition. 



