INDEX 



293 



Potash in soils, sources of- . . 1 79 

 and lime, joint use of 185 



muriate of . 181 



sulphate 181 



removed in crops 177 



Potassium compounds of soil. 64 



Potato, fertilizers for 223 



food requirements of. 223 

 soils 17 



Preliminary trials, with fer- 

 tilizers 208 



Pulverizing soils 249 



Questions 275 



Rainfall and crop produc- 

 tion 23 



Rape, food requirements of .224 

 Reaction of soils, determina- 

 tion of 268 



References 284-7 



Relation of crop and soil 



type 258 



Reverted phosphoric acid . 168 



Review questions 275-283 



Roberts 36, 146, 248 



Rock disintegration 45, 55 



Rocks, composition of 51, 56 



properties of 268 



Rolling of soils 33, 249 



Roots, action on soil... 214, 233 

 Root crops, fertilizers for . . .224 



Rotation of crops 230-7 



principals involved ... 231 



length of 236 



problems 237 



and farm labor 234 



and humus 232 



and insects 236 



and soil nitrogen 233 



Rotation and soil water . . 234 

 and weeds 236 



Salt as a fertilizer 193 



Sand, grades of 1 1, 13 



Seaweeds as fertilizers 194 



Sedentary soils 50 



Seed, amount of per acre 257 



Seed bed, preparation of 247 



Seed residues 125 



Sheep manure 142 



Silicon and silicates 59-60 



Silt particles 12 



Size of soil particles 1 1 



Skeleton of soils I r 



Small manure piles 153 



Sodium compounds of soils. 65 



Soil, composition of 80- 1 



conservation of fertil- 

 ity 241 



exhaustion 230, 259 



management 258 



particles, study of. . 268 



solution of 65, 163 



types 17 



Soils and agriculture, rela- 

 tion of 260 



crops suitable for 258 



Soot 193 



Specific gravity of soil 1 1 



Spring plowing 34 



Stassfurt salts- 180 



Stockbridge . . 1 1 , 23 



Stock farming and fertility . . 243 



Storer 60, 123 



Strand's plant ash 194 



Street sweepings 194 



Stutzer 126 



Sub-soiling 33 



Sugar beets, fertilizers for- -223 

 beet soils 19 



