70 



BULLETIN F.' 



From this table it is clear that, during the short interval of 

 about one hour during which the water was running between 

 the rows and another hour after the water was turned off, a 

 very marked change had occurred in the distribution of nitrates 

 in the soil. As soon as the water was led into the furrows per- 

 colation began and in front of the advancing water, as well as 

 laterally from it under the rows from both sides, capillary ac- 

 tion shoved the water, already in the soil, together with the ni- 

 trates which it carried, downward and sidewise, causing a con- 

 centration at the places where the capillary water accumulated. 



IN MEDIUM CLAY LOAM. 



In the next table are cited similar observations made at Mad- 

 ison, Wis., also in a potato field, but on a medium clay loam 

 richer in nitrates. 



Concentration of nitrates by lateral capillary movement in a me- 

 dium clay loam rich in nitrates. 



In all of these series, the determinations were made upon 

 composite samples of 4 cores, each taken within 10 to 12 inches 

 of the place where the ones of the preceding series were taken. 

 In the first group of the table the interval of time between the 

 taking of the two sets of samples is too short to admit of either 

 nitrification or denit'rification having occurred to such an extent 



