2 9 2 



INDEX 



Nitrogen, compounds of soil. 61 

 compounds, solubility 



of 271 



deficiency of, in soil . . 209 

 loss of, by fallowing.. 1 19 



losses of, from soil 1 1 1 



ratio of, to carbon no 



removed in crops.... 108 

 in commercial fertil- 

 izers 200 



amount of, in soils... 107 



in organic forms 106 



as nitrates 109 



availability of 107 



forms of 106 



origin of 106 



Nitrogenous manures 121 



Number of soil particles 15 



Odor of soils 42 



Organic acids, action of, upon 



soils 70-1 



Organic compounds of soil, 



classification of 86 



source of 86 



Organic nitrogen 121, 126 



Organisms, ammonia produc- 

 ing 117 



of soil 117 



nitrifying 114 



products of 118 



Osborne 16 



Orthoclose 52 



Oxidation of soil 40 



Peat 127, 133 



Percolation 26 



Permanent meadows, manur- 

 ing of 226 



Permeability of soils 36 



Phosphate fertilizers .164 



commercial forms 167 



manufacture of 170 



as plant food 164 



removed by crops 165 



reverted 168 



rock 169 



slag 171 



use of 171 



Phosphoric acid of commer- 



mercial fertilizers ..167 



available 164, 176 



acid in soils 166 



acid, deficiency of 210 



removal in crops 165 



testing for 271 



value of 171 



Phosphorus compounds of 



soils 61 



Physical analysis of soils . . . 267 



property of soils 9 



modified by farming. . 96 



Plant food, classes of . 65-6 



ash and fertilizers 216 



distribution of 78 



in soil solution . . .66, 163 



Plants, crowding of, in seed 



bed 257 



Plowing, depth of 35 



energy required for . . 248 



fall 34 



spring 34 



influence of, on soil --249 

 influence of moisture 



on 247 



influences nitrifica- 

 tion 247 



Potash fertilizers 177 



use of 185 



of commercial fertil- 

 izers 202 



