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Advisor(s)
Abstract(s)
Biofertilizers are fertilizing products containing living microorganisms that, when applied to the soil or directly to a seed,
colonize the rhizosphere and/or the plant promoting growth by increasing the availability of nutrients. Biofertilizers
may improve the bioavailability of nutrients through natural processes such as biological nitrogen fixation, phosphorus
solubilization, or through the synthesis of growth promoting substances. Organic fertilizers enriched with heterotrophic
free-living nitrogen-fixing microorganisms have recently appeared on the market, seeking to enhance nitrogen fixation by
placing the microorganisms directly in the food substrate. However, these nitrogen-fixing microorganisms are ubiquitous
in agricultural soils, which allow question of the usefulness of enriching the organic fertilizers in such microbes. Unless the
placement of the microorganisms next to the food substrate can give them competitive advantages and increase the biological
nitrogen fixation. Field and pot experiments were carried out to compare the performance of two organic fertilizers enriched
with free-living nitrogen-fixing microorganisms with other organic and mineral fertilizers. A sequence of horticultural crops
(Lettuce-Lettuce-Turnip) was repeated for two years in the same field plots and pots. In the third year, barley was grown
without fertilization to assess the residual effect of the fertilizers. Anion exchange membranes were used to monitor nitratenitrogen
in the soil and plant dry biomass and nitrogen concentration in plant tissues to assess plant nutrient uptake and
nitrogen use efficiency. Biofertilizers displayed results lower than mineral fertilizers but higher than organic fertilizers without
microorganisms’ addition.
Description
Keywords
Nitrogen fixation Free-living fixers
Citation
Arrobas, Margarida; Rodrigues, M.A. (2017). Is the enrichment of organic fertilizers with nitrogen-fixing microorganisms effective in soils ubiquitous in these microbes? In Annual Congress on Soil Sciences. Madrid