TABLE 26 



NITROGEN CONCENTRATIONS IN SATURATION 

 EXTRACTS AND TILE DRAINAGE FROM IRRIGATED SITES 



Soil 

 Series 



Physiographic 

 Position 



No. 



of 



Sites 



Saturation 



Extracts 



Average—' 



NO^-N (mg/l) 



No. of 

 Tile 

 Systems 



Tile Drainage 



Average—' 

 NO3-N (mg/l) 



Ambrose Older alluvial fan 

 Lethent Basin rim 



Lost 

 Hills 



Older alluvial fan 

 Panhill Recent alluvial fan 



1 

 2 



1 

 1 



Panoche Recent alluvial fan 11 

 Sorrento Recent alluvial fan 1 



59 

 II+2 



3 



35 

 37 

 IT 



3 



2 



3 

 k 

 8 

 6 



T 

 20 



i^5 

 38 

 11 



1/ Average NO3-N in soil from 1 to 8 feet, I966-6T. 



2/ Weighted average concentrations over two years, I96T-68. 



Comparisons of nitrogen concentrations of extracts and tile 

 drainage from similar virgin soils could not be made because 

 tile systems are rarely installed in virgin areas. 



Saturation extracts of virgin Panoche and related soils 

 (Panhill and Lost Hills, Table 21) of one area averaged 

 S6 mg/l in the tile zone. Tile drainage from another area 

 of Panoche soils, farmed but not previously tiled, averaged 

 H^ mg/l, considerably less than that found in the saturation 

 extracts . 



Future Tile Drainage 



Tile drainage system installation is expected to continue in 

 the northern area (Byron-West ley and Westley-Gustine) , 

 Tentative plans have been made for installations south of 

 the town of Tracy and near the towns of Patterson and Newman. 

 Tile systems have been installed nearly every year in the 

 Gustine-Mendota area and are expected to continue, especially 

 since the introduction of plastic conduit. In the Tulare 

 Lake area, the number of tile drainage systems has not 



79 



