Fungos micorrízicos arbusculares e matéria orgânica do solo de um módulo de cultivo intensivo de hortaliças orgânicas

Abstract

This work comprises part of a larger study and aims to assess the dynamics of nutrients, organic matter and arbuscular mycorrhizal fungi on soil in a complex agro-ecosystem. The study area comprises an experimental module of intensive organic vegetable production, implemented in 2010, with 1 ha, which aims to replicate agricultural reality of Rio de Janeiro. This production module is located in Seropédica-RJ, Brazil, on “Fazendinha Agroecológica do Km 47”. The system does not present intake of animal inputs, half of the area has intensive production vegetables and half of the area has crop species for biomass production and annual cultures. Crop rotation prioritizes growing vegetables from March to October, especially hardwoods, and corn, okra and green manure from November to February. The evaluated parameters were: texture, elevation, nitrogen, phosphorus, potassium, calcium, magnesium, pH, total organic carbon, carbon humic acids fractions and light fraction, glomalin, density and diversity of glomerosporos. In order to assess the impact of each crop cycle, there were three samplings, the first collection in March 2013, at the time of preparation of soil for early sowing vegetables, the second collection in October / November 2013, at the end of cycle vegetables, and the third collection in March 2014, new beginning cycle of vegetables. The geostatistics was used to display the spatial and temporal variability of the complex production system and mean tests were to compare cropping systems. The results reflect the intensive management performed during the vegetable cycle, the N, P and K decreased on the year, unlike Ca, Mg and pH. Carbon Organic soils showed an increase after the second collection in areas with planting vegetables, but the final balance of the year was negative. The humin was the top fractions and fulvic acids were fraction who reflect the intensive management, higher than the humic acids in these areas. The total Glomalin showed good correlation with soil carbon. The easily extractable glomalin reflect the intensive management decreasing its concentration after the vegetable cycle. Regarding the spore density, responded to this intensive management, with high densities after the vegetable cycle. The highest densities were noted in the areas with the lowest fertility rates. However, the diversity of spores was less in these areas, with greater redundancy species. In areas with diverse planting vegetables diversity was higher. We conclude that the work shows the effect of different cultures and managements on organic matter and mycorrhizal fungi community, contributing for discussion of impact that agroecological production systems have on soil quality. A geostatistics is efficient for spatial analysis and temporal agro-ecosystem, facilitating future decision making.