600 STATE BOARD OF AGRICULTURE. 



In general the residuary effects of the acid phosphate treatment was 

 to leave the soil extracts richer in all elements except K. A few excep- 

 tions occur, but evidently the reaction products, excepting SO3 com- 

 binations, are less soluble than those from KCl and other more soluble 

 salt treatments and not readily leached from the soils in first leachings. 

 Quantities of Ca, fixed CO, and Fe and Al were notably increased over 

 the checks. 



The hydrated lime treatment gave more Ca, Mg, Na, P, SO3, fixed 

 COo and Fe and less SiO,, K, CI, (with one exception) and Al in the 

 second leachings than did the checks. 



The residuary effects of the CaSO^ treatment are very marked. SiO. 

 and K were found in lesser amounts in the extracts than in the checks, 

 while the quantities of Fe and Al (excepting one case), and P in the 

 acid soils, were increased. In these instances the quantities of Mg were 

 reduced as was the quantities of Ca in two cases, while the increases 

 were small. It is astonishing that the Ca content of a soil extract is 

 reduced in this manner after treatment with CaSO^. Less P was found 

 in these extracts from the alkaline soils than from checks. 



NaCl tends to leave the soil solutions lower in SlOo, Ca, Mg, K, and 

 higher in Na, P, CI, and fixed COo, then the checks. Less Na but more 

 P is found in the acid soil extract which coincides with the results from 

 the KCl treatments, 



NaNOg acts similarly to NaCl in that the quantities of SiOo, K, and 

 Ca Mg (excepting soil No, 2) are decreased over the check and quantities 

 of Na, P, Fe and fixed CO, notably increased. 



The second leachings from the Ca3(P04)o treatments with few excep- 

 tions are much higher in content of soil elements than the checks, ex- 

 cepting SiO, and K which are less. The soluble phosphate shows prac- 

 tically the same effects. 



Practically the only marked difference between the residuary effects 

 of the phosphates and CaCOn is the presence of more Ca ond less P in 

 the extracts from the CaCOg treatments. 



It may be observed that the residuary effects of KCl, CaSO^, NaCl 

 and NaNog tend to reduce the quantities of Ca, Mg, SiO, and K (except- 

 ing the KCl treatment) in most cases, while acid phosphate, hydrated 

 lime, Cag(POJo, Ca(HPOJ, and CaCO, effect only the SiO, and K in 

 this respect. In case of the first named salts it appears that some of 

 the Ca and Mg in particular become quite soluble and if leached away 

 the soil does not readily recuperate from the effects of the treatments 

 and the solutions may lack sufficient of these elements for maximum 

 plant growth. This effect would tend to lower the crop producing power 

 of a soil low in content of soluble Ca and Mg and subject to leaching, 

 in a comparatively short period of time. The recuperatory power of a 

 certain soil under these treatments would probably depend upon the 

 quantities of Ca and Mg present and up to a certain point of fertilizing 

 salts added. On soils low in these elements it is probable that the use 

 of these salts in fertilizers would sooner or later bring about a need for 

 :in application of lime. 



In case of the second list of compounds named tlie recuperating power 

 of the soils appears not to liave been impaired except in respect to K. 

 This effect is probably duo to tlie fact tliat the solubility of Ca and Mg 



