356 SOIL CONDITIONS AND PLANT GROWTH 



Methods of Sand and Soil Cultures. See Hellriegel (130^) and 

 Sand, McCall, A. G., Journ. Amer. Soc. Agron., 1915, 7, 249- 

 282 ; Soil Sri , 1916, 2, 207-253 ; Journ. Amer. Soc. Agron., 1918, 

 IO, 127-134. Hoagland, D. R., Journ. Ag. Res., 1919, 18, 177- 



Comparison of Sand and Water Cultures, Hoagland, D. R., Journ. 

 Ag. Res., 1919, 18, ii. 



