INDEX. 



333 



Plowing, how done 275 



purpose and results of 178 



" how performed.... 179 



hillsides 1S2 



" in manure 195 



Pollen of plants 255 



Potatoes, cultivation of. S06 



" sweet, cultivation ol 307 



Potash 108 



" as plant food 108 



" sulphate of. 109 



" muriate of 109 



" nitrate of. 110 



" oxalateof 110 



" tartrutesof Ill 



" citrates of Ill 



" German salts of 112 



" salts 220 



Potassium, its compounds 107 



" chloride 109 



Practice of soiling 287 



Ripening, changes produced by ...258 



Rocks, composition of 123 



" character of. 123 



" effect of, upon the soil 125 



" a guide to the character 



of soils 129 



Roots, functions of 82-241 



" penetration of 163 



" power of selecting food 242 



" rejection of useless mat- 

 ter by 211 



" store nutriment 2-15 



Root crops, cultivation of. 304 



Roots and stubble, value of. 207 



Rotation of crops 106 



Rotation, longer advisable 281 



Rye, for fodder 290 



" cultivation of 300 



Salt , composition of. 111-221 



" asa fertilizer Ill 



" fertilizer for mangels 137 



Sandstones 128 



Sandy soils, improvement of 166 



Sap, circulation of in plants 247 



Seed, selection of. 268 



Seeds of plants, how formed 259 



" always reproduce them- 

 selves 262 



Shell lime 217 



Silica, as a constituent of plants. ..116 

 Silicon.... ....116 



Silo, construction of. 287 



Snow, its forms and character 46 



Soda Ill 



" nitrate of, effects of on wheat 91 



Sodium, its compounds Ill 



chloride Of. Ill 



" sulphate of 112 



Soil, accumulation of carbon in... 19 



" virgin, formation of 119 



" functions of the 142 



" exhaustion of. 143-149 



' ' the manufactory of plant 



food 144 



" barren, composition of 146 



" a storehouse of plant food 153 



" improvement of by chemi- 

 cal means 196 



" natural fertility of. 150 



Soils, physical properties of. 130 



" sandy, free from frost 131 



" loess, of Nebraska 131 



" limestone 131 



41 difficult to plow 132 



' ' absorption of moisture by ... 133 



" peaty, value of. 133 



" alluvial 128 



" fertile, composition of.. ..127-145 



" variations in 128 



' ' improvement of, by mechan- 

 ical methods 155 



" drainage, effect of 155 



" effects of variations of, in 



plants 152 



" dark, absorb heat 140 



" thorough pulverization of, 



necessary 137-154 



" effects of cultivation of 136 



Soiling crops 286 



Solar rays, influence of 25 



Soot from soft coal 232 



Special manures 228 



Species, the persistence of 257-262 



Sporting of plants ....269 



Springs, nature and action of. 168 



Stamens of plants 254 



Starch 237 



" composition of 62 



" converted into sugar 236 



Stems, functions of. 247 



Subsoil plowing 162 



Sugar, needed for germination 237 



" composition of. 237 



Sulphate of lime li:;-220 



\ Sulphur, its combinations 116 



Sunlight, effects of on plant 

 trrowth 250 



