Occurrence of arbuscular mycorrhizal fungi after organic fertilization in maize, cowpea and cotton intercropping systems/Ocorrencia de fungos micorrizicos arbusculares apos adubacao organica em sistemas consorciados de milho, feijao e algodao

The effect of organic manure on the community of mycorrhizal fungi (AMF) was evaluated in maize, cowpea and cotton intercropping systems in a semi-arid region of Brazil over two consecutive years. The experiment was conducted using a randomized block design with four replicates and six soil treatments: (M) goat manure incorporated in the soil before planting; (G) gliricidia prunings incorporated before planting (M+G) manure and gliricidia incorporated before planting; (GS) gliricidia applied on the soil surface 45 days after planting; (M+GS) manure incorporated before planting and gliricidia applied to the surface 45 days after planting; and (C) control treatment without incorporation. It was not possible to identify the best treatment for both years in terms of spore density, mycorrhizal colonization and glomalin content. However, there was a significant effect from the fertilization treatments when compared to the control in most treatments. In both years, M+GS favored glomalin and AAMF sporulation in the cotton plots. In the second year, which had low rainfall, there was an increase in production of spores, glomalin, colonization and AAMF species richness irrespective of soil incorporation and culture. Plots that were fertilized with manure presented greater AAMF species richness regardless of the year and crop type. Keywords: mycorrhizal association, Gliricidia sepium, goat manure, green fertilizer. O efeito da adubacao organica sobre a comunidade de fungos micorrizicos arbusculares (FMA) em sistemas consorciados com milho, feijao e algodao foi avaliado no semi-arido paraibano, ao longo de dois anos. O experimento foi conduzido em delineamento de blocos casualizados com quatro repeticoes e seis tratamentos: (M) esterco incorporado no solo antes do plantio; (G) ramas de gliricidia incorporadas antes do plantio; (M+G) esterco e gliricidia incorporados no solo antes do plantio; (GS) gliricidia aplicada em cobertura 45 dias apos o plantio; (M+GS) esterco incorporado antes do plantio e gliricidia aplicada em cobertura 45 dias apos o plantio; (C) tratamento controle. Nao foi possivel identificar um melhor tratamento, em ambos os anos, em termos de densidade de esporos, colonizacao micorrizica e teor de glomalina. Entretanto, houve efeito significativo das incorporacoes na maioria dos tratamentos quando comparados ao controle. Em ambos os anos, M+GS favoreceu a producao de glomalina e a esporulacao de FMA no sistema com algodoeiro. No segundo ano, de poucas c