340 STATE BOARD OF AGRICULTURE. 



2. When solutions of alkaline salts were used to treat the- soils fixation 

 of one ion was independent of the fixation or combination of the other. 



3. Iron was fixed in the soils from FeCla, and acid salt, and a closely 

 proportional quantity of calcium liberated except in case of a soil containing 

 limestone. 



4. Anions or acid radicals of the salts used that form insoluble compounds 

 with calcium or magnesium were fixed by the soils and similar components 

 that form soluble compounds with these soil elements were not fixed by the 

 soils. 



5. Potassium and calcium were fixed from their hydroxides, but no evi- 

 dence of exchange of soil elements was observed. 



6. In case of the neutral salt treatments the fixation of potassium cor- 

 related with the liberation of calcium and magnesium and in one series 

 of non-carbonate soils a relationship was observed between fixation of potas- 

 sium and quantities of calcium and Si02 dissolved by 0.2 N HCl. The 

 fixation of magnesium correlated with exchange of calcium and fixation of 

 calcium with exchange of magnesium. 



7. The fixation of an element was reversed by neutral salts containing 

 other elements in all cases studied except the FeCls treatments. 



8. Potassium, calcium and magnesium were fixed by natural soils in 

 unequivalent quantities, but when soil calcium and magnesium were largely 

 replaced by a single element, potassium, sodium or magnesium, then the 

 fixation of the first named elements became closely equivalent. 



9. Soils fixed much greater quantities of calcium from CaCl2 after l»eing 

 treated with MgCl2 than they did before the treatment. 



10. With few exceptions fixation was greater in quantity in alkaline soils 

 than in acid soils of the same class. 



11. Fixation from neutral salts was probably due to a calcium-magne- 

 sium-ferro-alumino-silicate; of hydroxides to acid silicates, and from hydro- 

 lyzing salts due to a combination of these soil components. 



12. Fixation from chemical salts and exchange of soil elements depends 

 upon the manner of dissociation of the salt used for treatments and the 

 solubilities of the compounds formed. The magnitude of fixation and 

 exchange depends upon the quantity relationships between the reacting 

 compounds. 



13. The results of this investigation are in accord with the chemical hypo- 

 thesis of Way (9, 10). 



14. There was no evidence of replacement of potassium, sodium, iron or 

 aluminum in any considerable quantity in the untreated soils studied. 



15. Fixation from neutral salts, hj^drolyzing salts or of hydroxides was 

 not a distinguishing characteristic of the acid soils. 



REFERENCES CITED 



(1) BouyoucoS; G. J. and McCool, M. M. 1915. The freezing point method 

 as a new means of measuring the concentration of the soil solution 

 directly in the soil. Mich. Agr. Expt. Sta., Tech. Bui. No. 24. 



(2) Bouyoucos, G. J. and Laudeman, W. A. 1917. The freezing point 

 method as a new means of studying velocity of reaction between soils 

 and chemical agents and behavior of the equilibrium. Mich. Agr. 

 Expt. Sta., Tech. Bui. No. 37. 



(3) Bouyoucos, G. J. 1916. Further studies on the freezing point lowering 

 of soils. Mich. Agr. Expt. Sta., Tech. Bui. No. 31. 



