602 STATE BOARD OF AGRICULTURE. 



GENERAL SUMMARY. 



No attempt is made in this bulletin to explain by processes of deduc- 

 tion what takes place in soils when fertilizer salts are added to them. 

 This subject is under investigation and data are being gathered for a 

 coming report. Some generalizations can be made from the data at 

 hand, however, which may have an important bearing on fertilization 

 and soil management in general. 



Processes influencing the quantities of soil constituents formed in the 

 extracts have been discussed under the general term of solubility. To 

 what extent the processes of true solubility, or chemical or physical re- 

 actions effect the results is not known. Effects produced by the different 

 treatments may be direct or indirect. In this connection the work of 

 Jensen (IG) is cited which shows that decomposing organic matter in- 

 creases the solubility of certain soil constituents; changes in concentra- 

 tion and the products of chemical or physical reactions may also effect 

 solubilities. Unquestionably, the effects produced by soil treatments are 

 highly complicated. 



These results show, however, that the treatments taken singly or col- 

 lectively have some certain well defined effects. The application of a 

 soluble compound to soils appears to completely change the chemical 

 composition of their extracts. These changes are in some instances pro- 

 found and when some of the soluble constituents are removed the soil 

 is left in a permanently changed condition. Another common effect of 

 the treatments used in this investigation was to greatly increase the 

 quantities of fixed CO, in extracts from second leachings; and of P in 

 both leachings with but two exceptions in case of the CaSO^ treatment. 

 The general depression of the solubility of potassium has also been noted. 



When KCl, CaSO^, NaCl and NaNOg were added to these soils, both 

 radicals of each salt appeared in the extracts in large quantities, with 

 the acid radical always in excess of the basic. The acid radical is ap- 

 parently principally in an easily soluble combination because it is found 

 only in small amounts in the second leachings, and the greater portion 

 of that added to the soils is found in the first extracts, but considerable 

 quantities of both radicals of all treatments are not reclaimed. This 

 tendency is not observable in case of CaOOg and the phosphates, the 

 extracts being enriched by each radical in approximately equivalent 

 quantities. Other basic ions go into solution as an effect of these treat- 

 ments, particularly Ca and Mg, and are readily washed from the soils. 

 A marked effect of the phosphate and CaCOg treatment was to increase 

 the total quantities of Fe and Al in the extracts. 



The soils were alkaline to litmus paper after treatment with hydrated 

 lime and CaCOg and leaching. All the other treatments left the soils 

 acid to litmus paper. These results also support the conclusion that 

 the neutral salts and phosphorus compounds used in this research destroy 

 the carbonates of the soils thereby changing the hydrolytic equilibrium 

 towards the acid side; that is, either .causing the soils to more nearly 

 approach an acid condition or become acid or to increase in acidity. 



