754 



INDEX 



Disk plow, 666. 



Disking to hold moisture, 714. 



Ditching machines, 649. 



Dolomite, 6, 9. 



Drag as soil pulverizer, 680. 



Drain till, quality, 640. 



Drainage and absorption, 368. 



Drainage and denitrification, 456. 



coefficient, 651. 



effects on soil, 630. 



effect on soil ventilation, 477, 488. 



effect on soil bacteria, 434. 



extent of need, 628. 



efficiency of fertilizer, 568. 



formation of humus, 152. 



history of development, 629. 



of irrigated and alkali land, 659. 



of land, indications of need, 627. 



methods, 634. 



muck and peat soil, 658. 



promoted by soil organisms, 422. 



reclamation of alkali land, 400. 



relation to green manure practice, 

 624. 



relation to colloids, 166. 



run-off checked, 269. 



systems, arrangement, 643. 



toxic materials eliminated, 137. 



use of explosives, 661. 



tile drains, 639. 



vertical, 660. 



Drainage water at Bromberg, 370. 

 Drainage water, composition, 369, 351. 

 Drainage water, relation of phosphates 



and carbon dioxide, 482. 

 Drains, protection of joints, 642. 

 Dried blood, 507. 

 Drift denned, 52. 

 Drought-resistant crops, 715. 

 Dry-farming practices, 713. 



principles, 712. 



drought-resistant crops, 715. 



soils best suited for, 716. 



extent, 717. 



Drying and wetting, effect on granula- 

 tion, 187. 

 Dust mulch, 272. 



Dust mulch under irrigation, 705, 710. 

 Duty of water in irrigation, 708. 

 Dynamite, drainage by means of, 661. 



Earthworms, action on soil, 19. 

 Earthworms and productiveness, 422. 

 Effective diameter of soil particles, 122. 

 Effective surface of soil, 125. 

 Effects of organic matter on soil, 150. 



Electrical production of nitrogen fer- 

 tilizer, 502. 



Elements of plant-food, 3. 

 Enzymotic action of bacteria, 129. 

 Enzymes, effect on plant-food, 438. 

 Enzymes in roots, 407. 

 Epidote, 9. 

 Erosion, agencies causing,' 14. 



effect of drainage, 633. 



in ditches, limits of grade, 636. 



ice as agency, 16. 



in irrigation canals, 694. 



rate of, in U. S., 14. 



wind action, 15. 

 Eskers, 50. 

 Evaporation and alkali, 282. 



and temperature, 314. 



and wind movement, 285. 



at Rothamsted, 271. 



from plants, 270. 



prevented by, 272. 



rainfall lost by, 271. 

 Excreta from animals, 577. 

 Exhaustion of soil, 419. 

 Expansion of minerals by heat, 16. 

 Explosives, drainage by means of, 661. 



Factors for plant growth, 3. 



Factory-mixed fertilizer, 563. 



Fall plowing, relation to dry-farming 



713. 



Fall and spring plowing, 283. 

 Farm manures, 577. 

 Farm manure, waste, 597. 

 Fats in soil. 127. 

 Fats, effect on capillarity, 211. 

 Feeding power of plants, 414. 

 Feldspar, as potash fertilizer, 524. 

 Feldspar in soil separates, 101. 

 Fermentation, effect on phosphates, 520 

 Fermentation of manure, 591. 

 Ferric phosphate availability, 337. 

 Fertilizers, 489. 

 Fertilizers and acidity, 381. 



amounts to use, 572. 



application of, 570. 



brands, 555. 



catalytic, 530. 



commercial value, 560. 



commercial, extent of use, 492. 



effect on toxic material, 137. 



factors in efficiency, 568. 



for special crops, 571. 



grades of, 562. 



home mixing, 563. 



incompatible material, 565. 



