TABLE 17 



AVERAGE TILE DRAIN DISCHARGE, NUTRIENT CONCENTRATIONS, 



AND TOTAL DISSOLVED SOLIDS FROM DIFFERENT SOIL SERIES 



AND PHYSIOGRAPHIC POSITIONS 



1/ Total Dissolved Solids 



series. The total discharge from this system was in excess 

 of 8.0 acre-feet per acre for 1968. Drainage from these and 

 a few other tile drainage systems in the study area represents 

 systems where more water was discharged than applied during 

 the irrigation season. 



Movement of subsurface water into tile systems from outside 

 influences (lateral movement from other irrigated areas, 

 canals, and other sources of water) was suspected in many 

 tile drains when discharges continued after irrigation had 

 ceased. Although lateral movement was apparent in several 

 tile drainage systems throughout the study area, none were 

 obvious as the two just mentioned. 



Tile drainage discharge expressed as acre-feet per acre 

 depends entirely upon one's interpretation of the acreage 



as 



63 



