INDEX 



3ii 



Wind, transport of, soil by, 10. 



Winogradsky on iron bacteria, 203, 

 286 ; on nitrification, 192 ; on 

 nitrogen-fixing bacteria, 186. 



Woburn, lime in soil at, 204 ; 

 residues left by ammonium salts 

 at, 232 ; weight of cubic foot of 

 soil at, 64 ; fruit farm, growth of 

 trees planted with grass, 112. 



Wollny on composition of soil gases, 

 13 ; on effect of slope on tempera- 

 ture, 133 ; on oxidation of humic 



acid, 173 ; on water required by 



crops, 89. 

 Worms, fine soil brought to surface 



by, 14. 

 Worn-out soils, 28, 257. 



Xerophytes, 272, 277, 288. 



Yeasts in the soil, 1 70, 204. 



Zeolites, 25, 39, 214. 

 Zircon, 34. 



