WATER SOILS. 551 



used, but the Norfolk sandy soil least and less than one-eighth that absorbed by the 

 Janesville loam, which produced the heaviest yields. While potash was absorbed 

 by all soils, in every case lime went into solution, and in larger quantities from the 

 four soils which gave the largest amounts of lime from treatment with distilled 

 water. So, too, the four soils yielding largest amounts of magnesia, under repeated 

 washing, gave this base over to the solution, but in three other cases magnesia was 

 absorbed. 



" Very large amounts of nitric acid failed to appear in the solution after contact 

 with the soils, anil it was clearly held back or transformed. Denitriheation, in the 

 biological sense, could not take place to this extent, (1) because the soils themselves 

 were repeatedly dried at 120° C, and came to this experiment warm from the dry 

 oven; (2) because sufficient time did not intervene for so much denitrirication to 

 have occurred as the result of vital activity. . . . 



" More potash, in every case but one, was absorbed than was required to repre- 

 sent the chemical equivalent of the nitric acid disappearing from the solution. The 

 retention of phosphoric acid was not very different with the different soils. . . . 

 The solution contained phosphoric acid enough to represent 29.55 parts per million 

 of the dry soil. In no case was this amount absorbed, and the amounts left in the 

 solution ranged betw-een 10 and 22 parts per million of the soil. . . . Comparatively 

 large amounts of S0 4 were also fixed by the four poorer soils, the Janesville loam 

 being the only one which corresponds with the observations of earlier investigators. 

 Chlorin is the only negative radicle existing in the solution used which does not 

 appear to have been fixed by the soils. ' ' 



As regards the relation between yields and absorbed and dissolved salts in case of 

 the manure solution it was observed that "when the four northern soils are com- 

 pared, as a group, with the four southern soils, it is clear that much larger yields are 

 associated with the power for larger absorption of potash and of total salts, and with 

 the larger solution as well, where that has taken place. In the case of the individual 

 members of the northern group, too, the yields and absorption of total salts rise and 

 fall somewhat together. The Selma silt loam and the sassafras sandy loam, each of 

 which is a stronger soil than its mate, have also a larger total absorption. 



"If water-soluble salts carried by soils are important factors of yield, and if the 

 absorbed salts are still recoverable by degrees under field conditions, and available 

 to crops, some such relations as have been pointed out should be expected to exist 

 between the more and the less fertile soils." 



Studies were also made of absorption by these soils from a guano solution; by the 

 same soils, washed 11 times with distilled water, from a prepared chemical solution; 

 and of absorption by marsh soils. 



The result of washing the soils "was the throwing out of solution much larger 

 amounts of every ingredient present except phosphoric acid. The amount of phos- 

 phoric acid present in this solution, however, was only 12 parts per million more 

 than in the one used in the guano series. 



"Another remarkable relation brought out in this series is that the absorption of 

 potash from this solution by the four northern soils averages nearly double what it 

 does for the four southern soils, and yet for all other ingredients the southern soils 

 have thrown out of solution more than the northern ones have, if we except sul- 

 phates, upon which they are practically equal in their effects." 



In the experiments with marsh soils samples "were collected from a black marsh 

 soil under three different crop conditions, (1) wdiere corn was very poor, (2) where 

 there was a fair average crop, and (3) where the corn had all died, possibly because 

 the soil had been too wet, and was at the time supporting a rank growth of weeds. 



"These soils were treated with two different solutions the usual time for washing 

 soil samples, and by the same method, except that in these cases solutions instead of 

 distilled water were employed. . . . 



