Avaliação dos atributos físicos e químicos do solo na prestação de serviços ecossistêmicos, sob diferentes sistemas de uso da terra no sul do Amazonas

Abstract

The conversion of forest areas into agricultural spaces has generated significant changes in the quality of soils in the Amazon. These transformations generate environmental impacts that, in turn, affect soil ecosystem services, making it essential to evaluate soil quality indicators that are measurable, economically viable, and representative of soil functions. In this sense, the objective of this research was to evaluate the physical and chemical indicators of the soil, under different land use systems, in the southern Amazonas. For this, four environments with specific characteristics for each use system were selected: açaí plantation, cassava plantation, pasture, and natural forest, the latter used as a reference area. The collections were carried out between the months of November and December 2022. For the cropping systems, 15 random sampling points were demarcated distributed throughout the areas. By opening small trenches (figure 5) in the 0-5 cm, 5-10 cm, 10-20 cm and 20- 40 cm layers, samples were collected in the form of clods and stored in identified plastic bags. In addition, samples were collected in the form of volumetric rings (figure 5) to evaluate the physical attributes and organic carbon of the soil. Soil analyses were performed at the Laboratory of Soda Biology of the Institute of Education, Agriculture and Environment – IEAA, of the Federal University of Amazonas – UFAM, in Humaitá, AM, Brazil. The data resulting from the laboratory analyses were subjected to descriptive statistical analysis and multivariate analysis, and comparisons of the means of the variables within each environment were analyzed by the Tukey test at 5% probability. The pasture had higher soil organic carbon contents in the layers at all depths, contributing to the provision of the ecosystem service of soil CO storage; on the other hand, it presented greater compaction and a lower relationship with the ecosystem service of water retention. The Natural Forest provides the ecosystem service of water retention, attributed mainly to the correlation with the gravimetric moisture attribute. The açaí system offers ecosystem services of nutrient cycling, but has lower gravimetric moisture contents and, consequently, less water retention. Finally, the cassava system was the system that contributed least to the provision of ecosystem services, with carbon contents intermediate between the pasture and açaí systems.