Microbial Processes Promising Technologies for Developing Countries (1979) / Chapter Skim
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4 Nitrogen Fixation
4 Nitrogen Fixation
Pages 59-79
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From page 59... ...
Bacteria that fix nitrogen in nodules on the roots of leguminous plants are called rhizobia (Figure 4.1~. Other microorganisms that produce nodules on certain nonleguminous plants are classified as Franks spp.
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From page 60... ...
6Q MICROBIAL PROCESSES S~BE ANS WITH NODUL E 5 F1X A1R NlTROGEN \w ~~ ~~ o # ~ ~ -_ f~1 / FICURE 4.1 RhizobisofthepIopeIkindappUedtolegum~ousseedsbe~Ieplan1~g caninducenodules OI nitrogen bctoIiestofonm ontheIOOtS.lhesepIovidetheplant with usablenKIogen.ThepIocessof~pply~gtheIb~obiatoseed~caDed Elocution. (PhotogIaphcouI1esyofJoeC.BuIton)
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From page 61... ...
There is voluminous literature on this point, but so many of the leguminous plants cultured in the tropics and subtropics are nodulated by the cowpea rhizobia that special mention is justified. The cowpea cross-inoculation group encompasses numerous genera and species of plants.
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From page 62... ...
Canavalia ensiformis ( ack bean) Lablab purpureus (hyacinth bean)
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From page 63... ...
-: ......... to $~|C$~@f ~166¢ BEAN FIGURE 4.2 Nodules or nitrogen factories on the roots of important food legumes: winged bean, Psophocarpus tetragonolobus; peanut, Arachis hypogaea; chickpea, Cicer arietinum; and field bean, Phaseolus Yulgaris (Photographs courtesy of Joe C
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From page 64... ...
Ethers me fictive; these produce large nodules and Ox appreciable amounts of nitrogen (Photographs courtesy of Joe C Burton)
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From page 65... ...
Forage legumes usually fix more nitrogen than do grain legumes because carbohydrate requirements resulting from seed development are small, whereas with grain legumes the developing large seeds impose a large demand on the carbohydrate supply. The amounts of nitrogen fixed are uncertain, because of the methods of measurement, but relative quantities as related to host species give valid comparisons (Table 4.21.
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From page 66... ...
Further, they will fix nitrogen for months, providing the pods are gathered regularly and not allowed to mature on the vine. Frankia-Nonleguminous Plant Associations Numerous nonleguminous trees and woody shrubs form root nodules and fix atmospheric nitrogen under natural conditions.
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From page 67... ...
Trees of the birch family, especially Alnus sp., provide wood for timber in many countries; the red alder (Alnus rubra Bong) (Figure 4.4)
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From page 68... ...
TABLE 4.3 Nitrogen Fixed by Various Genera and Species of Nodulating Nonleguminous Trees and Shrubs Species Age-Years Nitrogen kg/ha/yr* Alnus crispa 0-5 362 15-20 1 15 1 0-60 40 Alnus glutinosa 0-8 125 20 56-1 30 Alnus ru bra 2-15 325 Gasuarina equisetifolia 0-13 58 Ceanothussp.
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From page 69... ...
· Surveys should be conducted to determine if nitrogen-~xing species of these nodulating nonleguminous plants grow in the lowland tropics. · Plants should be evaluated for nitrogen-fixing ability as well as for their value as human and animal food.
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From page 70... ...
7Q MICROBIAL PROCESSES FIGURE 4.S Smog Doming nitrogen ~ctoI~s on ~ Hooded tics paddy. The small fern Czar p~m hubris blue~Ieen algae, ~~e~ razor, which ~ nitrogen Together they provide nitrogen HI ~ Intuit crop.
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From page 71... ...
increases. Limitations Use of the Azolla-Anabaena association for food production is limited to agricultural soils that can be flooded, and it is best adapted to rice culture.
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From page 72... ...
In rice culture, the blue-green algae can be depended on to provide nitrogen consistently. In long-term soil fertility experiments at the International Rice Research Institute (IRRI)
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From page 73... ...
· Methods of culturing starter cultures and distributing dependable inocula should be developed; biological and chemical methods of control will result in better husbandry and more efficient handling of effective algae.
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From page 74... ...
It takes the equivalent of about 50 kg of sucrose for Azotobacter species to fix 1 kg of nitrogen at the oxygen concentrations found in air. The inoculation of soils and seeds of nonleguminous plants with preparations of Azotobacter chroococcum has been practiced in Russia and India for many years.
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From page 75... ...
with Azotobacter paspali in tropical soils resulted in nitrogen fixation stimulated new interest in this field. Interest was heightened by the subsequent finding by Dobereiner in Brazil that an associative symbiotic relationship between Digitaria decumbens, cultivar "transvala," and the microorganism Azospirillum lip oferum also brought about nitrogen fixation.
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From page 76... ...
· Attempts Would be made to modify the rhizosphere bacterial community to allow the inoculum strain to become established. References and Suggested Reading Rhizobium-Leguminous Plant Associations Brill, W
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From page 77... ...
In Plant and soil special volume: biological nitrogen fixation in natural and agricultural habitats. Proceedings of the Technical Meetings on Biological Nitrogen Fixation of the International Biological Program (Section PP-N)
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From page 78... ...
10, Basic Life Sciences, Proceedings of a Conference on Limitations and Potentials of Biological Nitrogen Fixation in the Tropics, Brasilia, Brazil Johanna Dobereiner, Robert H Burris, Alexander Hollaender, Avilio A
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From page 79... ...
I Watanabe, International Rice Research Institute, Los Banos, The Philippines.
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