SOIL CONDITIONS AFFECTING PLANT GROWTH 41 



jl 



CL 



20 



*- 10 



o 



02 



-030 



10 



Soil. 



10 Vv/ateif. 



F IG< 6. Effect of varying water and nitrate supply on the growth of tomatoes 



in pots of sand and of soil. (E. J. Russell.) 



