Frações da matéria orgânica em solo arenoso e argiloso tratados com isolados fúngicos sob soja e milho em casa-de-vegetação

Abstract

Due to the constant growth of the world's population, there is a need for greater agricultural productivity. In this sense, the search for beneficial organisms for plant growth has been intensified. Beneficial microorganisms can serve as an alternative to mining or synthetic agricultural inputs. These microorganisms can not only influence the plant's defense system, pathogen control, and phytohormone regulation but also improve soil conditioning, such as increasing soil organic carbon content. Understanding the soil organic matter content and its correlation with microbial activity and biomass can reveal mechanisms of soil conditioning. The objective of this research was to understand the effects of five rhizospheric fungal isolates on the organic matter, respirometry (CO2 emission), and microbial biomass carbon of sandy and clay soils under soybean and corn growth in a greenhouse. To this end, four trials were established: with corn and soybean growth on sandy and clay soil, respectively. Each trial included six treatments: 1 – Non-inoculated control; 2 – Application of Beauveria bassiana; 3 – Application of Metarhizium anisopliae; 4 – Application of Pochonia chlamydosporia; 5 – Application of Purpureocillium lilacinum; 6 – Application of Trichoderma asperellum. The general hypothesis was that the application of fungal isolates would alter the concentration of fulvic acid, humic acid, and humin fractions in the soil under crop growth. Soil fertility, total organic carbon, fulvic acids, humic acids, humin, carbon cycle enzyme activity, CO2 emission, and microbial biomass carbon were analyzed. The experiment was designed in a completely randomized block design. Among the humic substances, Purpureocillium lilacinum, Pochonia chlamydosporia, and Trichoderma asperellum showed lower results for humin in corn grown in sandy soil, while humic and fulvic acids did not show statistically significant differences with the application of fungal isolates. Beauveria bassiana, Purpureocillium lilacinum, and Trichoderma asperellum in soybean under sandy soil showed lower total organic carbon results. Parameters such as pH, base saturation, potential acidity, and magnesium were also affected. B. bassiana in corn under clay soil resulted in lower dry root mass. No statistically significant differences were observed in basal microbial respiration, microbial biomass carbon, and enzymatic activity. This work demonstrates the quality and application of the studied fungal isolates, in addition to presenting several options for applicable research to better understand the relationship between fungi and soil organic matter.