TABLE OF CONTENTS (Continued) 



Page 



Short-term Nitrogen Variability 47 



Hourly 48 



Daily 48 



Monthly Variations In Individual Systems .... 50 



Monthly Variations in Composited Drainage .... 50 



Areal Variability 51 



Individual Systems 51 



Composited Drainage 52 



Tile Drain Discharge 52 



Nitrogen 52 



Phosphorus 53 



Total Dissolved Solids 53 



Variability Due to Agricultural Practices 53 



Influence of Crops on Tile Discharge 53 



Influence of Crops on Nitrogen Concentrations ... 54 



Irrigation Influence on Discharges 55 



Irrigation Influence on Nitrogen Concentrations . . 55 



Individual Systems 55 



Denltriflcation 56 



Dilution 57 



Nitrogen in Irrigation Water 58 



Fertilization 58 



Leaching 58 



Applied Nitrogen Versus Discharged Nitrogen ... 59 



Phosphorous Fertilization 60 



Variability Due to Physiography 6l 



Discharge 6l 



Nutrients and Total Dissolved Solids 6l 



Variability Due to Soils 62 



Discharge 62 



Nutrients 64 



