Indicadores de qualidade do solo em sistemas agroflorestais

Abstract

Agroforestry systems, due to their multifunctionality, have been considered an excellent strategy to increase food production while at the same time complying with social and environmental objectives, meeting the objectives of sustainable development (SDGs), especially the SDGs 13 and 15. These systems can improve soil quality by increasing soil organic matter (MOS), altering soil structure, fertility, and biological properties. The objectives of this thesis are: i) to evaluate the chemical, physical and biological properties of the soil in an unmanaged pasture, different agroforestry systems, and secondary forest; ii) understand the relationships between litter quality, SOM, and main soil quality parameters; and iii) Assess the sensitivity of soil quality indices to detect differences caused by land use conversion. Soil, macroinvertebrates, and litter were collected in April and September 2018 under five land use, including three agroforestry systems, an unmanaged pasture, and a secondary forest in Sapucaia-RJ, Brazil. The correlations between litter quality, SOM, and soil parameters suggest that high-quality litter inputs (i.e., low C: N ratio) along with SOM are essential to stimulate biological activity. In the second chapter, it is shown that management practices influenced arbuscular mycorrhizal fungi (AMF) sporulation and the total number of species in agroforestry systems, and that the AMF community is correlated with other essential soil parameters. In addition, glomalin contributes to increasing soil organic carbon (SOC) content, especially in agroforestry systems and pasture areas. In the third chapter, it is shown that the effects of adopting agroforestry systems on soil carbon fractions were perceived in the more superficial layers (0-5, 5-10 cm), mainly in the particulate fraction. Seasonality influences the dynamics of the SOC and its fractions. The carbon management index (CMI) was sensitive to detect changes due to changes in land use and showed that pasture accumulates carbon in the soil even with signs of degradation. In chapter four, the Soil Management Assessment Framework (SMAF) index was sensitive to detect changes in soil quality caused by land use conversion.