INDEX 



759 



Muck, as fertilizer, 545. 



and manure, 613. 



and moisture control, 272. 



nitrogen compounds in, 133. 



specific growth of, 113. 

 Mulch and the control of alkali, 402. 

 Mulch, depth of, 278. 



depth in irrigation farming, 705, 715. 



dry-farming, use in, 714. 



effectiveness in arid regions, 277. 



effect other than on moisture, 280. 



factors of effectiveness, 275. 



formation of, 276. 



functions of, 274. 



kinds of, 273. 



management of, 278. 



of soil, 233. 



r6sum6 of control, 278. 



usefulness of, 282. 



water saved by, 279. 

 Mulching grain crops, 282. 

 Muriatic acid used in soil survey, 728. 

 Muscovite, 9. 

 Muscovite, solubility, 339. 

 Mycorrhiza, relation to fertility, 423. 

 Mycotrophic plants, 423. 



Natural mulch, 273. 

 Negative acidity, 376. 

 Nematodes in soil, 424. 

 Nephelite, solubility, 339. 

 Nitrate assimilation by bacteria, 456. 

 Nitrate of calcium, fertilizer, 505. 

 Nitrate of soda, as plant food, 498. 

 Nitrate, reduction of, 455. 

 Nitrates, conserved by green manure, 

 620. 



constituent of alkali, 392. 



effect of lime on, 536. 



in soil, effect of absorption on, 341. 



loss from soil, 454. 



product of decay processes, 130. 



returned to surface, 454. 

 Nitric acid method of analysis, 338. 

 Nitric acid solution of soil, 329. 

 Nitrification in soil, 447. 



effect of aeration, 452. 



effect of antiseptics, 465. 



effect of carbon bisulfide, 466. 



effect of depth, 453. 



effect of organic matter, 449. 



effect of sod, 452. 



temperature for, 435. 

 Nitrobacter in soil, 448. 

 Nitrogen, 4, 12. 



absorption of, 367. 



Nitrogen, added to soil by legumes, 621. 



available from atmosphere, 501. 



chemical estimation, 329. 



cycle, 443. 



effects on plant growth, 547. 



effect on toxic material, 137. 



fertilizers, 493. 



fertilizer from the air, 501. 



fertilizers, organic, 507. 



fixation, 457. 



fixation and mycorrhiza, 428. 



fixation by molds, 427. 



fixation, non-symbiotic, 463. 



fixing organisms, 463. 



forms in soil, 493. 



forms used by plants, 448, 494. 



found in animal manures, 597. 



in humus, 147. 



loss in drainage, 372. 



loss from Rothamsted soil, 500. 



necessary to plants, early studies, 

 491. 



supply and bacteria, 428. 



utilized by bacteria, 459. 

 "Nitrogen" culture, 461. 

 Nitrosococcus in soil, 448. 

 Nitrosomonas in soil, 448. 

 Nodules on plant roots, 458. 

 Number of soil particles, 118. 

 Nutrient salts, absorption of, by plants, 

 404. 



absorption by soils, 349. 



selective absorption, 362. 



Odometer used in soil survey, 727. 



Oils, effect on capillarity, 214. 



Oils in soil, 128. 



Oily material, and capillary movement, 



226, 228. 

 Oily materials in soil, 275. 

 Olivine, 9. 



Open ditches, construction, 635. 

 Open-ditch drainage, objections, 634. 

 Optimum water content, 262. 

 Orchards, manure in, 617. 

 Organic colloids, 157, 161. 

 Organic fertilizer availability, 510. 

 Organic constituents of soils, 2, 12, 128, 



131. 

 Organic decay and soil temperature, 315. 

 Organic matter, 12. 



absorption by, 365. 



and capillary water, 218. 



catalytic action, 529. 



composition in soil, 135. 



effect on granulation, 190. 



