Arbuscular mycorrhizal fungus in microbial activity and aggregation of a Cerrado Oxisol in crop sequence

Abstract

Soil structure has major influence on ecosystem sustainability and plant growth. Arbuscular mycorrhizal fungi (AMF) are an important functional group of soil microbiota, acting in the process of aggregation, especially in agroecosystems and related to the production and plant diversity. AMF are widely distributed in tropical agroecosystems and are extremely important for development of many agricultural crops. The present study evaluated the effect of inoculation with Glomus macrocarpum in different crop sequences on plant growth, microbial activity and aggregation of a Cerrado Oxisol. The study was conducted in a completely randomized design in a4 x 4 factorial scheme. Treatments consisted of four conditions of elimination and/or introduction of AMF (NS-NI: non-sterilized and non-inoculated; NS-I: non-sterilized and inoculated; S-NI: sterilized and non-inoculated; andS-I: sterilized and inoculated) and four crop sequences (Panicum maximum/Panicum maximum, Brachiaria ruziziensis/ soybean, sorghum/soybean and Stylosanthes spp./soybean). Inoculation favored growth of Stylosanthes spp. by increasing plant growth in up to 91% when inoculated. None of the grasses benefited from G. macrocarpum introduction. We observed that G. macrocarpum inoculation associated with indigenous AMF increased microbial biomass, phosphatase activity, mean geometric diameter and mean weighted diameter. The results indicated the beneficial effects of inoculation, which reflected in soil structure improvement and, hence, to agroecosystems sustainability.Index terms: Microbial carbon, acid phosphatase, mean geometric diameter, mean weight diameter, soil structure. RESUMOA estrutura do solo exerce importante influência na sustentabilidade dos ecossistemas e no crescimento de plantas. Os fungos micorrízicos arbusculares (FMAs) constituem um importante grupo funcional da microbiota do solo, atuando diretamente nos processos de agregação, principalmente em agroecossistemas e têm relação direta com a produção e diversidade vegetal. Esses estão amplamente distribuídos no agroecossistemas tropicais e são extremamente importantes para o crescimento de várias espécies vegetais agrícolas. No presente estudo, avaliou-se o efeito da inoculação com Glomus macrocarpum e diferentes sucessões de culturas no crescimento vegetal, na atividade microbiana e na agregação de um Latossolo Vermelho de Cerrado. O estudo foi conduzido em delineamento inteiramente casualizado com arranjo fatorial 4 x 4. Os tratamentos constituíram da combinação entre quatro condições de eliminação e/ou introdução de FMA (NS-NI: não autoclavado-não inoculado; NS-I: não autoclavado-inoculado; S-NI: autoclavado-não inoculado; S-I: autoclavado-inoculado) e quatro sucessões de culturas (Panicum maximum/Panicum maximum; Brachiaria ruziziensis/soja; sorgo/soja; Stylosanthes spp./soja). A inoculação com FMAs favoreceu o crescimento do estilosantes, apresentando aumento de até 91% na produção de massa seca quando inoculado. Nenhumas das gramíneas beneficiaram-se com a introdução de G. ...

Arbuscular mycorrhizal fungi in soil aggregates from fields of "murundus" converted to agriculture

“…In mesoaggregates, there was no difference between the studied areas and spore density. Spore density was higher in micro-and macroaggregates, but was lower in mesoaggregates; these results are similar to those obtained by Vilela et al (2014) in a Cerrado Oxisol. The area with 13 years of conversion showed results close to those of the areas between and at the top of the murundus, with a higher Ambispora leptoticha (1) Times of conversion: 6, 10, and 13 years.…”

“…These results are indicative that there is greater physical protection of AMF spores to predators, such as nematodes , in meso-and microaggregates than in macroaggregates; in contrast, the greatest amount of mycelium and production of glomalin favor the stabilization of these microaggregates (Wright & Upadhyaya, 1998;Rillig & Mummey, 2006;Vilela et al, 2014).…”

High rates of agricultural gypsum affect the arbuscular mycorrhiza fungal community and coffee yield

“…The higher EE-GRSP content in macroaggregates than in mesoaggregates and microaggregates (Fig. 2) is a common effect (Vilela et al 2014) that was not modified by gypsum rates. The physical effect of extraradical hyphae of approximating soil particles to form macroaggregates, results in a greater release of glomalin, which acts as a cementing and stabilizing agent in macroaggregates.…”

Biochemical and Biological Properties of Soil from Murundus Wetlands Converted into Agricultural Systems

“…No-tillage stands out among the sustainable management systems. This is because soil mobilization and straw deposition provide greater physical protection to the soil surface layer; increase water retention (Tormena et al, 2007;Marouelli et al, 2010;Vilela et al, 2014;Carneiro et al, 2015), and soil carbon stock (Alburqueque et al, 2015;Sá et al, 2015;Ferreira et al, 2016;Souza et al, 2016); promote greater biological diversity (Campos et al, 2016) and the continuity of the ecological functions of the soil; and directly increase crop yield (Carneiro et al, 2009). Soils under no-tillage system are more sustainable for the soil biological (Calegari, 1998); however, in tropical regions, the consolidation and efficiency of the system may take longer due to the higher rate of decomposition of organic residues, which implies long-term benefits (Pragana et al, 2012).…”