The assessment of microplastics (MPs) in terrestrial ecosystems has garnered increasing global attention due to their accumulation and migration in soils, which may have potential impacts on soil health, biodiversity, and agricultural productivity. However, research on their distribution and interactions in soil remains limited, especially in tropical regions. This study aimed to characterize MPs extracted from tropical soil samples and relate their abundance to soil and terrain attributes under different land uses (forest, grassland, and agriculture). Soil samples were collected from an experimental farm in Lavras, Minas Gerais, Southeastern Brazil, to determine soil physical and chemical attributes and MP abundance in a micro-watershed. These locations were also used to obtain terrain attributes from a digital elevation model and the normalized difference vegetation index (NDVI). The majority of microplastics found in all samples were identified as polypropylene (PP), polyethylene (PE), polyethylene terephthalate (PET), and vinyl polychloride (PVC). The spatial distribution of MP was rather heterogeneous, with average abundances of 3826, 2553, and 3406 pieces kg⁻¹ under forest, grassland, and agriculture, respectively. MP abundance was positively related to macroporosity and sand content and negatively related to clay content and most chemical attributes. Regarding terrain attributes, MP abundance was negatively correlated with plan curvature, convergence index, and vertical distance to channel network, and positively related to topographic wetness index. These findings indicate that continuous water fluxes at both the landscape and soil surface scales play a key role, suggesting a tendency for higher MP accumulation in lower-lying areas and soils with greater porosity. These conditions promote MP transport and accumulation through surface runoff and facilitate their entry into the soil.

Para aumentar la calidad y el rendimiento de frutos en plantaciones de camu-camu, actualmente se viene buscando alternativas de producción orgánica. En ese sentido, el presente trabajo tuvo por objetivo determinar el efecto de diferentes biofertilizantes en el desarrollo vegetativo y productivo de plantas de camu-camu. Para ello, fue conducido un experimento mediante un diseño de bloques completamente al azar (DBCA) en esquema factorial (5Bx5C), con cuatro repeticiones y una planta por unida experimental. El primer factor (B) estuvo constituido por 5 tipos de biofertilizantes: B1) vacaza (estiércol de vaca), B2) gallinaza (estiércol de gallina de postura), B3) guano de isla (estiércol de aves de mar), B4) pollinaza (estiércol de pollo) y B5) sedimentos de rio, y el segundo factor (C) por cinco concentraciones de biofertilizante: C1) 0, C2) 2, C3) 4, C4) 6 y C5) 8%. Después de 210 días, fue verificado que, el biofertilizante guano de isla estimuló mayor emisión de brotes nuevos (1773,73) y el biofertilizante vacaza presentó los mejores resultados de botones florales, número de frutos de cosecha y rendimiento de frutos (t ha^-1) con 4611,67; 2926,85 y 28,8 en las dosis 6; 8 y 8%, respectivamente. Se concluye que, el biofertilizante vacaza (VA) incrementó la calidad y el rendimiento de frutos de camu-camu en suelos de restinga. Así también, el biofertilizante guano de isla (GI) fue el segundo en presentar los mejores resultados, sin embargo, el alto contenido de N retardó el desarrollo normal de las fases fenológicas.

The objective of this study was to assess the impact of Azospirillum brasilense in conjunction with nitrogen fertilization on structural, morphogenetic, yield-related, and chemical characteristics of Urochloa humidicola cultivated in the Amazon savannah. Treatments consisted of five nitrogen application rates (0, 50, 100, 150, and 200 kg ha-1), both with and without A. brasilense inoculation. The experiment was laid out in a completely randomized design with a 5×2 factorial arrangement, including four replications. The morphological composition of the pastures, morphogenetic and structural characteristics and chemical composition of the forage were evaluated. The utilization of A. brasilense, either alone or combined with nitrogen fertilization, did not influence the enhancement of forage yield. However, nitrogen fertilisation led to consistent increases in production, primarily through an increase in leaf and culm components and a reduction in the proportion of dead material in pastures. It also led to a linear increase in the proportions of NDF, ADF and CP in the forage. The use of A. brasilense does not alter the production and chemical composition of the forage, while nitrogen fertilization favors the management of pastures with U. humidicola grown in Amazonian savanna soil.

The genus Capsicum includes economically important species important species, widely used as food and condiment. A critical stage of its production is obtaining quality seedlings, better adapted to transplanting, vegetative and productive development. The use of plant growth-promoting rhizobacteria (PGPR) in the production of high-quality vegetable seedlings can contribute to a more efficient agriculture, less dependent on crop protection products and mineral fertilizers. Therefore, the aim of this study was to select PGPR from pepper plants in the Brazilian Amazon savanna, using the quality index (QI) as a selection criterion and to evaluate their ability to produce promoters of plant growth, such as indole-3-acetic acid (IAA), phosphate solubilization (SCa-P), and biological nitrogen fixation (BNF). The experiment was conducted in Randomized Block Design (RBD) with four replications and 139 treatments, including a positive control (PC) and a negative control (NC). The ten best isolates were identified molecularly and subjected to three biochemical tests. The ten best bacteria demonstrated high growth promotion of pepper seedlings in the in vivo tests. Although not all isolates in this group demonstrated SCa-P and BNF capabilities, all of the isolates produced IAA. The bacteria isolated from the rhizosphere promoted the production of seedlings with higher QI, but the selection of bacteria based solely on the production of IAA, SCa-P, and BNF in vitro may not be enough to find the best isolates for promoting growth in pepper seedlings, as not all exhibited these mechanisms even though they improved the quality index (QI) of the seedlings.

Olive groves (Olea europaea L.) are highly susceptible to soil degradation, particularly water erosion, due to sparse canopy cover and wide inter-row spacing. This study evaluated the effect of different vegetation cover management practices on soil quality and erosion control in a tropical olive grove in southeastern Brazil. The experiment followed a randomized block design with five treatments: exposed soil (BS), olive trees on exposed soil (OB), olive trees with spontaneous vegetation managed with herbicide (OVH), with mowing (OVM), and with mowing + localized weeding (OVMC). Physical, chemical, and biological indicators and losses due to water erosion were analyzed. The OVM and OVMC treatments promoted an increase in soil organic matter (up to 39 g kg⁻¹), microbial biomass carbon (40% higher than BS), enzymatic activity, and glomalin, improving aggregate stability (WMD of 4.9 mm) and reducing soil and water losses by more than 99% compared to exposed soil. The BS and OB treatments, on the other hand, showed higher acidity, lower microbial activity, and greater susceptibility to erosion. The study reinforces that maintaining vegetation cover improves soil quality, mitigates erosion, and promotes the sustainability of olive groves in tropical regions.