HYDRATURE AND PLANT PRODUCTION 



285 



decline of the production curve is greater than later on. The same has been 

 found with green gram (Fig. 11). We may learn from this, that the direct 

 lack of water or lowered water availability due to salt depends on the same 

 basic fact: that is decrease of hydrature. 



O 0-2 O-A 0-6 0-8 



Salt content of soil in % 



l-O 



Fig. II. Curve of decreasing yield with increased salt content of the soil for green 

 gram. After Development Board Baghdad, 1958. 



Certainly exceptions may occur, particularly if other factors are changed. 

 This can be illustrated by the following example (Fig. 12). If we increase 

 the salt content of the soil and at the same time also nutrients (nitrate) of the 

 soil, then no decrease in yield is found in case of barley because the fertilis- 



0-1 0-5 



% salts in so 



Fig. 12. Yield curve of barley (Murakish) in relation to salt content in soil and nitrate 

 present. After Development Board Baghdad, 1958. 



