406 



SOIL CONDITIONS AND PLANT GROWTH 



Water supply in soil, available for 



plants, 221 et seq. 

 effect on bacterial activity, 



272, 276. 

 numbers, 272, 



276, 286. 



movement of, 218 et seq. 



utilisation of food, 38. 



the "principle" of vegetation, 3. 

 vapour, absorption by soil, 170. 

 Waxlike constituents of soil, 144. 

 Weathering of soil, 93, 99. 

 Weeds, checked by heavy crop, 55. 



Weeds, control by metallic salts, 85. 

 Wilting coefficient, 221. 



phenomena of, 221. 



point, 168, 221. 

 Woodland soils, nitrates in, 146. 



nitrification in, 146. 

 nitrogen content, 55. 



ZEOLITES, reactions of, 103. 



supposed presence in soil, 109. 

 Zinc salts, beneficial in small quantities, 



56, 85. 

 harmful in larger amounts, 85. 



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