2. On the basis of observations made during this Investiga- 

 tion, nutrient concentrations In the tile drainage from 

 the San Joaquin Valley are not expected to change 

 appreciably within the next 50 years. 



3. Nutrient concentrations and total dissolved solids In 

 composited drainage can be expected to veiry Inversely 

 with the seasonal application of irrigation water. 



4. Dilution and denltrification are highly suspect as the 

 reasons for decreases in concentration of nutrients and 

 T'DS in tile drainage during the summer. 



5. Denltrification is believed to be the main reason for 

 low nitrogen concentrations in tile drainage from the 

 basin rim and basin soils. 



6. The areal variability of nitrogen found in the tile 

 drainage is more dependent upon the particular soil 

 series and the physiographic position of the tile 

 systems than on agricultural Influence. 



7. The relative concentrations of nitrogen in tile drainage 

 from future tiled areas can possibly be predicted on the 

 basis of current tile drainage data, along with a 

 representative soil -nitrogen sampling program. 



8. High phosphorous concentrations in tile drainage from 

 certain areas is attributed to indigenous quantities in 

 the soil made available by anaerobic soil conditions. 



9. The quantity of drainage from a given area depends more 

 on the interrelationships of physiographic position, 

 soil stratigraphy and texture, and irrigation than on 

 irrigation alone. 



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