Emerging Technologies to Benefit Farmers in Sub-Saharan Africa and South Asia (2009) / Chapter Skim
Currently Skimming:
5 Technologies for Soil Improvement
5 Technologies for Soil Improvement
Pages 145-176
The Chapter Skim interface presents what we've algorithmically identified as the most significant single chunk of text within every page in the chapter.
Select key terms on the right to highlight them within pages of the chapter.
From page 145... ...
It presents both some well-known methods for protecting and building soils that have not been widely adopted in SSA and SA but are essential for soil health and some novel, science-based concepts for improving soil that require research and additional exploration. Soil Degradation in Sub-Saharan Africa and South Asia The severe problems of soil degradation and desertification in SSA and SA are attributed to the long-term use of extractive farming practices that fail to rebuild the soil with organic material and mineral nutrients that maintain soil productivity and prevent erosion.
|
From page 146... ...
Nevertheless, successful soil management systems have several common objectives: to increase carbon content, enhance water infiltration, ensure the availability of water at the plant-root zone, reduce erosion, create a positive nutrient budget, and encourage beneficial organisms.
|
From page 147... ...
. The fundamental effects of the techniques in Box 5-1 are to improve soil structure, provide nutrients essential for plant growth, and maintain water availability in the soil.
|
From page 148... ...
• Land-use planning and land-tenure reform. To improve soil nutrient budget: • Integrated nutrient management.
|
From page 149... ...
Extractive farming practices are unsustainable, but adoption of management practices listed in Box 5-1 can help to create a positive nutrient balance in the soil. Integrated nutrient management techniques consist of a combination of organic amendments, such as the use of manure and compost, and the judicious use of inorganic fertilizers (Vanlauwe and Giller, 2006)
|
From page 150... ...
Conserving water in the root zone and enhancing the efficiency of its use require that soil structure and quality be improved (Rockstrom et al., 2007)
|
From page 151... ...
The maintenance and enhancement of soil organic matter, the use of biosolids or mulch, and conservation and no-till techniques are important strategies for improving soil structure. Mulching with biomass or plastic is also effective in reducing water losses by evaporation.
|
From page 152... ...
Several technologies that are emerging from those fields of science are described below. Remote Sensing of Plant Physiology for Nutrient Management and Soil Quality More effective use of remote sensing technologies could enable farmers to better manage inputs to increase crop yields, decrease input costs, and reduce the potential for adverse environmental effects.
|
From page 153... ...
. Considering the extremely low rates of nitrogen application in SSA, improved nitrogen fertilizer practices, such as fertigation with drip irrigation, can enhance nutrient-use efficiency and substantially increase crop yields.
|
From page 154... ...
. Alternatively, zeolites can be used in soil remediation to absorb metal cations and reduce local concentrations of toxic substances that inhibit plant growth and nitrogen-fixing soil microbes (Pisarovic et al., 2003)
|
From page 155... ...
Development of Transgenic Nitrogen Fixation in Non-legumes As noted earlier, biofertilization accounts for about 65 percent of the nitrogen supply of crops worldwide, primarily through Rhizobiaceaelegume symbiosis, in which Rhizobium bacteria fix atmospheric nitrogen and deliver it to plants via nodules on roots (Lugtenberg et al., 2002)
|
From page 156... ...
Ortwin Meyer at the Universität Bayreuth found that Streptomyces thermoautotrophicus isolated from a burning charcoal pile could fix nitrogen (Gadkari et al., 1992)
|
From page 157... ...
portion of the total soil space where environmental conditions are sufficient to support microbial life. The rhizosphere is biologically and chemically different from bulk soil and very more important in determining the effects of plant pathogens, plant growth-promoting microbes, and biogeochemical processes that together strongly affect the yield and quality of crops.
|
From page 158... ...
It may be that they stimulate greater production of root exudates and increase root development that provides enhanced nutritional benefits and space for microbial colonization, giving microbes with phytostimulating properties an evolutionary advantage. Although the mechanisms of the relationship of rhizobacteria to plants are not yet well understood, the use of rhizosphere microbes that stimulate plant growth presents a promising opportunity to increase crop yields (Broughton et al., 2003)
|
From page 159... ...
. Such advances indicate that it is possible to manage soil microbial communities to suppress soilborne diseases and improve crop productivity (Mazzola, 2004)
|
From page 160... ...
. Such an approach has already proved useful in collecting indigenous fungi that acted as effective inoculants to suppress soilborne diseases caused by nematodes (Olatinwo et al., 2006)
|
From page 161... ...
There has long been interest in developing systems of biological nitrogen fixation for non-legume crops, such as rice, wheat, sorghum, and millet. A wide array of root endophytic bacteria that can fix nitrogen have been identified (Box 5-4)
|
From page 162... ...
The most notable example for practical use of biological nitrogen fixation is sugarcane, in which 60 to 70 percent of the nitrogen comes from endophytic bacteria (Boddey et al., 1995)
|
From page 163... ...
. Research is needed on the mechanisms of endophytic colonization relative to root characteristics and soil conditions that would enable beneficial bacteria to thrive and elude plant defenses.
|
From page 164... ...
Agriculture might be transformed if we can combine knowledge of the microbial ecology of phosphorus-enhancing microorganisms with plant breeding or insertion of transgenes to develop roots with architectures, exudates, and signaling that optimize root and microbial responses to increase phosphorus uptake by crops.
|
From page 165... ...
(2001) showed that inoculation of sorghum with Azospirillum brasilense significantly reduced the adverse effects of saline irrigation water because of stimulation of root development, delayed leaf senescence, and improved water uptake in saline soils (Sarig et al., 1990)
|
From page 166... ...
To benefit farmers in SSA and SA, research should focus on local crops and local soil communities. Teams of soil and rhizosphere microbial ecologists, geneticists, molecular biologists, plant physiologists, plant breeders, agronomists, and anthropologists need to be assembled in an integrative project to conduct multidisciplinary research on the major crops of the regions.
|
From page 167... ...
1997. Effect of inoculation with plant growth pro moting rhizobacteria (PGPR)
|
From page 168... ...
1995. Biological nitrogen fixation associated with sugarcane and rice: Contributions and prospects for improvement.
|
From page 169... ...
1994. The use of yield increasing bacteria as plant growth promoting rhizobacteria in Chinese agriculture.
|
From page 170... ...
2001. Cytokinin production by plant growth promoting rhizobacteria and selected mutants.
|
From page 171... ...
1980. Enhanced plant growth by siderophores produced by plant growth promoting rhizobacteria.
|
From page 172... ...
2008. Relative effects of biological amendments and crop rotations on soil microbial communities and soilborne diseases of potato.
|
From page 173... ...
in exudates and extracts of canola seeds treated with plant growth-promoting bacteria.
|
From page 174... ...
2005. Crop residue management for nutrient cycling and improving soil productivity in rice-based cropping systems in the tropics.
|
From page 175... ...
2003. Plant growth promoting rhizobacteria as biofertilizers.
|
Key Terms
This material may be derived from roughly machine-read images, and so is provided only to facilitate research.
More
information on Chapter Skim is available.