520 



INDEX 



-PAGE 



Glacial soils, modified by water . . 59 



Occurrence of 56 



Physical character of 57 



Relation to underlying rocks . 55, 60 



Grain, separate, structure 89 



Granular structure 91 



Granulation, relation to texture. . . 92 



Due to ice crystals 108 



Relation to soil moisture 156 



Granules, cementation of 106 



Relation to checking 106 



Grass crops, absorption of nutri- 

 ents 295 



Protection to surface 113 



Gravitational water 160 



Capacity 162 



Injurious to crops 163 



Movement of water 165 



Relation to porosity 161 



Relation to texture 161 



Water, affected by percolation. 164 

 Gravity, affects capillary distribu- 

 tion 148 



As agency of soil transportation . 45 



Green manures 384 



Green manures, and humus supply. 132 



Cereal crops 387 



Leguminous crops 385 



May be injurious 195 



Ground limestone, effect on soil. . .353 

 Growth of plants, influence of tem- 

 perature on 449 



Growth, requirements of plants for . 1 



Guano, composition 333 



Gypsum, effect on soil 354 



Hall, effect of sodium nitrate on 



structure 118 



Hardpans, broken up by subsoil- 



ing 219 



Hardpan soil, objections to 475 



Hard surface soil, repels rain 



water 216 



Harrow, as cultivator 478 



Scotch chain 486 



Types of 482 



Use in mulching land 209 



Heat and cold, agency of rock de- 

 cay 18 



Frost action on rock 20 



Mechanical action of 19 



Heat, increases solvent action .... 19 

 Heat of the soil, functions of 448 



PAGE 



Heat of soil as factor in plant 

 growth 1 



See, also, Temperature. 

 Heat, specific, of soil and water. . .455 

 Heaving, relation of drainage to . . . 245 

 Hellriegel, best soil moisture con- 

 tent 156 



Water used by plants 134 



Henneberg and Stohmann, vexperi- 



ments with soil absorption. . .297 



High grade fertilizers 343 



Hilgard, nitrogen in humus 123 



Volume weight humus 128 



Hillside plow, advantages of 475 



Hoof meal 334 



Horizontal movement of water. . .172 

 Horizontal movement under field 



conditions 184 



Horse manure 368 



Hosmer and Whitney, soil moisturel57 



Humates 127 



Humid and arid soils 64 



Conditions, efficiency of mulch . 198 



Properties 79 



Humid climate, requirements of 



irrigation in 226 



Organic matter in 125 



Regions, difficulty of keeping 



mulch 204 



Soils, composition of 65 



Humus, defined 121 



Humus, carbon in 123 



Affects water capacity 153 



Effect on absorption 300 



Effect on color and temperature 



of soil 457 



Effect on structure 113 



Nitrogen in .123 



Plasticity 129 



Some properties of 115 



Volume change 128 



Hunt, growth of corn crop 135 



Hydration, defined 2] 



Hydration, example of 2] 



Hydrogen, as plant food element . 3 

 Hygroscopic water, character and 



amount 143 



Relation to texture 144 



Use of 194 



Ice as agency of rock decay 27 



Ice crystals form lines of weakness .108 

 Relation to granulation 108 



