TABLE 6 



TILE DRAINAGE SYSTEMS AND ACRES SAMPLED 

 BY SOIL SERIES AND PHYSIOGRAPHIC POSITIONS 

 WITHIN THE MAJOR TILED AREAS 

 1968 



The monitoring program consisted of measuring tile discharge 

 and collecting samples of tile drainage for analyses of 

 nutrients and total dissolved solids. Mineral saimples were 

 collected during the winter and summer of each year; 

 dissolved oxygen samples were only collected once during the 

 investigation. 



F low Measurement . Tile drainage discheirge was measured 

 whenever sajnples were taken. Several methods were used to 

 determine the flow, depending upon the design of the individ- 

 ual tile outlet or dischsirge structure. All methods used 

 were volumetric procedures set forth in numerous standard 

 irrigation and drainage texts or necessary modifications of 

 the standard techniques. 



The two methods used most in this study are the "bucket and 

 stopwatch method", used mostly for small flows, aind the 

 "float method", a technique devised to measure very high 



34 



