522 STATE BOARD OF AGRICULTURE. 



In Table V it sliould be noted, tliat 18a, of A as described above was 

 a secondary extraction (p. 515). Since a part of the solution was re- 

 moved in the first extraction, the results of the second one show a slight 

 lowering in the figures witli one or two exceptions but these differences 

 are not marked. 



A comparison is also made of the small and large cylinders with the 

 various types of soils. Soils Nos. 27, 28 and 29 of A were from the same 

 source but taken at different times, similarly those of B, E and F were 

 likewise so taken. 3 and 3a were the same at the start but the moistures 

 of the separate portions were made up at different times. The others 

 were obtained at different places. 



Taken on the whole the extracts from the two cylinders agree quite 

 closely in nearly all of the determinations. In some the results are 

 closer than those in others. A change in specific gravity produced sim- 

 ilar change in specific conductivity and total solids. The change was 

 not so marked in the osmotic pressure. or the depression of freezing point 

 on account of a closer reading not being made. Solution 2a of Soil 27 

 was the portion that came with the oil later. The osmotic pressure in 

 these cases varied in a similar manner as specific gravity, but for some 

 reason or other the total solids were higher. 



In the same types of solids, the increase in moisture content causes a 

 decrease in total solids in parts per million. This is noticed in A, B 

 and C. The soils in E were taken from a depression where washings from 

 a sandy loam were deposited, and Avere taken at different points. These 

 facts may explain why tlie concentration of its extractions did not fol- 

 low the above rule. The peat samples also were obtained from two en- 

 tirely different places. No. 22 contained some washings from the sur- 

 rounding knolls. 



In comparing the results procured from similar soils having different 

 moisture contents, it should be noted that their total solids and also 

 inorganic matter are in a general way inversely proportional to their 

 moisture contents. In most of the cases illustrating the above state- 

 ment, the ratios are not close due to the fact lliat the soils were not por- 

 tions of the same sample and were taken at dift'erent times. It is a well 

 known fact that samples taken will vary somewhat in the analytical re- 

 sults. From the entire table, it may be concluded that the concentration 

 of the soil solution varies according to its moisture content. If the mois- 

 ure content increases, the parts per million of the salts in solution de- 

 creases. This does not bear out the conclusions of Whitney and Cameron\ 

 They say that ''while some variations occur in the composition and con- 

 centration of the soil solution, in the case of the great majority of cul- 

 tivable soils their variations are within comparatively narrow limits. 

 The nature of the solution is but seldom permanently affected by the 

 addition of ordinary mineral fertilizers and it seems safe to say there- 

 fore, the concentration with respect to the mineral plant food constit- 

 uents per unit of solution is approximately constant. Considering the 

 wide variations in the percentages of water present in different soils, 

 however, the amounts of dissolved plant foods in them may be quite dif- 

 ferent." 



^Whitney. M. and Cameron. P. K. The Cheniistrv of the Soil as related to Crop Pro- 

 duction. Bui. 22, Bur. of Soils, U. S. Dept. of Agri. (i'J03) p. 63-4. 



