592 STATE BOARD OF AGRICULTURE. 



(14, McCool aud Millar (23), Bouyoucos and McCool (5), Bouyoucos 

 and Laudeman (G) and others, have produced data showing a close 

 relationship between composition and concentration of the soil solution 

 and plant activities. That the solution in various soil layers changes 

 in composition as soluble salts move through soils is shown by McCool 

 and Wheeting (22). These changes in composition must surely affect 

 solubilities of soil elements aud growth of plants. 



The problem undertaken in this research was suggested by Dr. M. M. 

 McCool, it being the general policy of the members of the Soils Section 

 to attack the problem from the physical and chemical angles and when 

 thought desirable and practicable, from the field standpoint as well. It 

 is the outgrowth of other work of a similar nature performed at this 

 Station and cited above, in which solubility of soil minerals under 

 different treatments and movements of soluble salts in soils were studied 

 principally by means of the freezing point method of determining con- 

 centrations in soils and soil exti'acts. It was thought advisable to 

 support this work by an extensive chemical research to determine if 

 possible the extent of the effect of various treatments upon each soil 

 component as well as the reactions involved. It was also planned to 

 study the residual as well as the immediate effects produced by the 

 treatments. 



Experimental. 



Four sandy loam soils as nearly true to type as could be obtained 

 without mechanical analyses were selected for experimentation. Two 

 of the soils were alkaline to litmus paper and two were acid. These 

 soils had been treated with manure in the fields, but never with com- 

 mercial fertilizers so far as could be ascertained. Analyses of the soils 

 are given in Table 1. The soils were prepared by passing the fine 

 material through a ten mesh sieve, they were then air dried in the 

 laboratory, and stored in galvanized soil bins. The four soils were 

 treated in duplicate sets with nine difl'erent fertilizing compounds in the 

 following manner: 1 gm, of oven dried fertilizing material was inti- 

 mately mixed Avith 1 kg. of air dried soil, the soil placed into a four 

 litre aspirating bottle the neck of which was fitted with a small cork. 

 The bottle was then inverted and placed on a ring support and the 

 soil saturated with distilled water (500 c.c.) through the bottom tubla- 

 ture which was finally fitted Avith a cork. After standing two days the 

 treated soils were leached with about three litres of distilled water in 

 500 c.c. portions, the small cork in the rubber stopper removed to 

 permit percolation and the water admitted through the tublature of 

 the bottle. Electrical resistance measurements were taken for concen- 

 tration of the several portions aud some of them were tested for re- 

 action by litmus paper and boiling with phenolph-thalein indicator. 

 Equal quantities of solutions were removed where necessary for these 

 tests so that the analytical results Avould be comparative. The soils 

 were then left saturated for a period of fifteen days and the leaching 

 procedure repeated. The soil extracts were then made exactly to three 

 litres using the last 500 c.c. portions in each case for the final measure- 

 ments. Chlorine, carbonates, reaction and in some cases nitrates were 

 determined on these natural extracts, after which they were treated 

 with 1 c.c. of concentrated nitric acid to flocculate colloidal material 

 and concentrated so that analytical determinations in milligrams rep- 

 resented parts per million on the soils. 



