Resumo

VITERI, Silvio E.; GRANADOS, Marcela  e  GONZALEZ, Ana Rosa. Potential of the rhizosphere and super four broths as biofertilizers for the sustainability of the onion bulb (Allium cepa) culture. Agron. colomb. [online]. 2008, vol.26, n.3, pp.517-524. ISSN 0120-9965.

The objective of this study was to evaluate the potential of the rhizosphere and super four broths as biofertilizers for the sustainability of the onion bulb culture. The broths were analyzed chemically and microbiologically, and applied to onion bulb pots at 10% concentration at 20, 40, and 60 days after transplanting. A complete randomized design was used with five treatments and 30 replicates. The variables evaluated were leaf number and length, and bulb diameter and weight. The chemical analysis showed that each broth contained a great variety of nutrient elements that are essential for the nutritional balance of the plant. Likewise, the microbiological analysis indicated that each broth represents a very important source of beneficial microorganisms, especially the rhizosphere broth due to its greater population of fungi and of total bacteria, nitrogen fixers, and phosphorus solubilizers. In relation to plant growth, each broth showed results similar to the chemical control, and superior to the mixture of them and the absolute control. However, the electrical conductivity values indicate that special care should be taken with the number of applications. For this reason its recommended that both biofertilizers be applied weekly, as a supplement to the fertilization, in a rotary sequence and in integration with agronomic practices that maintain adequate levels of organic matter to secure the multiplication and activity not only of the microorganisms introduced through the biofertilizers but also the indigenous soil populations.

Palavras-chave : biological agriculture; sustainable agriculture; biofertilization; agricultural bio-inputs.

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