420 



INDEX 



Ammonium sulfate, 399 

 Amphibole, 3 



Analyses, chemical, of adobe, 65 

 Analysis, mechanical or physical, 



123 



physical, systems of, 124 

 Andesite, 7 



Animals, decomposition by, 25 

 Apatite, calcium phosphate, 5 

 Appalachian Mountain and Plateau 



Province, 81 



Apparent specific gravity, 175 

 Aqueous rocks, 7 



Area, and projects, irrigation, 258 

 internal, of soil types calculated 

 from physical composition, 

 182 



of soil surveyed in the United 

 States by Bureau of Soils to 

 1915, 78 



of spheres, columnar arrange- 

 ment, 181 



or internal surface, 181 

 Arid soils, 74 



nitrogen in humus of, 147 

 subsoils, and humid, 70 

 Arrangement of particles, 179 



columnar, area of spheres, 181 



or vertical, 180 

 oblique, 180 



Artificial mulch, defined, 233 

 Aspirator, King's, 128 

 Atkinson, A., and Nelson, J. B., stor- 

 ing rainfall, Montana, 248 

 Atlantic and Gulf Coastal Plains 



Province, 91 



Atmosphere, carbon dioxide in, 20 

 Atmospheric pressure, changes in, 



factor in aeration, 311 

 effect on percolation, 219 

 Auger, soil, 119 

 Available moisture, 214 



increased by drainage, 223 

 Averitt, A. D., plant food in soil 

 areas of Kentucky, 393 



Babb, table, sediment carried by 



streams, 35 

 Bacteria, conditions for development, 



319-321 

 aeration, 320 

 food, 319 

 light, 321 

 moisture, 319 



Bacteria, conditions for develop- 

 ment, physical composition 

 of soil, 321 

 reaction, 320 

 temperature, 320 

 distribution of, 318 

 number of, effect of lime upon, 



321 



per gram of air-dry soil, 319 

 Bacterial action, effect of potassium 



carbonate upon, 321 

 Barley, yield of, continuous cropped 



vs. after fallow, 249 

 Barnyard manures, 161 

 Barometric pressure, changes in, 



factor in aeration, 311 

 Bartlett, W. H., expansion of rocks 



on heating, 13 

 Basalt, 7 

 Basic slag, 402 

 Bates, with Lynde, osmosis in soils, 



212 



Beach or Marram gras-s, transplant- 

 ing, 56 

 Beavers, J. C., manure excreted by 



farm animals, 162 

 value of increase for manure, 

 heavy and light applications, 

 168 

 Bennett, H. H., Bureau of Soils, soil 



survey, 78-111 

 Biological effects of organic matter, 



150 



Biotite, black mica, 4 

 Black alkali, neutralization of, 286 

 Black locusts, hold sand, 59 

 prevent washing, 368 

 " Blowout," in sand dune, 59 

 Bog, climbing, 28 



quaking, 28 



Bogs, see hummocks, 30 

 Boiling and freezing points, colloids, 



effect on, 131 

 Bone meal, 400 

 Boulder, granite, 51 



limestone, showing glacial 



scratches, 42 



Boulders, from moraine, 51 

 Bouyoucos, G. J., effect of color on 



radiation, 295 

 on temperature of sands, 



302 



specific heat of soil constituents, 

 299 



