Dec. i, 1920 Effect of Season and Crop Growth on Soil 



403 



Table I. — Relation of physical state to the electrolyte concentration of the soil extract 



Soil 

 No. 



Condition of soil. 



14 

 iC 



f Cropped. . . 

 (.Uncropped . 

 /Cropped. . . 

 \ Uncropped . 

 f Cropped. . . 

 1 Uncropped . 

 f Cropped. . . 

 \ Uncropped . 

 f Cropped. . . 

 1 Uncropped . 

 (Cropped. . . , 

 1 Uncropped. 

 /Cropped. . . . 

 [Uncropped . 

 f Cropped. . . . 

 \ Uncropped . 

 /Cropped. . . . 

 1 Uncropped . 

 f Cropped. . . . 

 \ Uncropped . 

 /Cropped. . . . 

 (Uncropped . 

 f Cropped. . . . 

 \ Uncropped . 

 f Cropped. . . . 

 1 Uncropped . 

 /Cropped. . . . 

 [Bin 



June 3. 



Turbid- 

 ity fl 



170 

 80 



33° 

 190 

 230 

 160 

 170 

 90 

 290 

 IOO 

 270 

 180 

 , 120 



95° 

 340 

 300 

 ,090 

 ,070 

 970 



i33° 

 .730 

 130 

 220 

 050 

 320 

 , 140 



Specific 

 resistance. 



Ohms. 



4, 

 3. 



6, 

 5. 



5, 

 3, 

 8, 

 7, 

 7, 

 7, 

 5> 

 3> 

 12, 



6, 



500 

 900 

 000 

 200 

 300 

 700 

 300 

 900 

 800 

 700 

 500 

 400 

 500 

 900 

 800 

 700 

 000 

 500 

 400 

 ©00 

 800 

 300 

 400 

 500 

 700 

 300 



July 26. 



Turbid- 

 ity." 



I, 400 

 640 



6, 620 

 220 

 IOO 

 60 

 410 

 160 



Specific 

 resistance. 



6,800 



5, IOO 



6, 900 

 4, 100 

 3>9°o 

 3,000 

 5,800 



4, IOO 



1, 060 

 610 



2, IOO 

 160 



1,320 

 I, 160 

 I, 260 

 I, 420 

 2,OIO 



T 5° 



10, 400 

 4, 400 



5>90° 



3.4oo 



16, 900 



8, 100 



9, 200 

 6,500 

 9, 000 

 4.300 



a Expressed in milligrams per 100 cc. 



It has already been pointed out that under certain conditions of storage 

 a soil may accumulate a large amount of soluble constituents. It was 

 thought to be of interest to compare a sample of soil which had been kept 

 in a bin for several years in a slightly moist condition with a sample of 

 the same soil cropped for several years. The two samples displayed 

 widely different concentrations of electrolytes, and the turbidity measure- 

 ments indicate that 20 times as much material was kept in suspension in 

 the cropped soil. These samples demonstrate the extreme effects which 

 may occur, even without fertilization or leaching. 



Sharp 1 has shown that salt-treated soils washed with water are made 

 far more impervious than soils washed with water without previous 

 treatment. If, however, a soil is very completely leached with distilled 

 water after stirring, an extremely impervious condition of the soil results. 

 At the same time the final leachings are exceedingly dilute, and the con- 

 centration of solution in the leached soil is so small as to be scarcely 

 determinable. In Sharp's experiments the impervious condition of the 



1 Sharp, L. T. op. cit. 



