Changes in land use can cause degradation of soil physical quality with negative effects on the environment and agricultural production. The effects of different land uses on soil physical-hydric attributes were studied in the Renato River and Caiabi River watersheds in the southern Brazilian Amazon. Three conditions of land use were evaluated: native forest, crops, and pasture in the headwater, middle, and mouth of each watershed. Particle size, particle density, bulk density, total porosity, macroporosity, microporosity, water contents at field capacity and permanent wilting point, and available water capacity in soil were evaluated in three soil layers down to 0.4 m. Data collected were subjected to the Kruskal–Wallis nonparametric test and Pearson’s correlations. Multivariate analyses were also performed using the principal component method. In the Renato watershed, in comparison with native forest, conventional management of pasture and crops caused soil physical degradation, increasing soil density in the surface layer and reducing macroporosity and total porosity. In the Caiabi watershed, converting native forest areas into pasture and crops altered water quality, influencing the water dynamics in the soil, by reducing soil water conductivity. Soil attributes varied by watershed, with texture variations between the headwater and mouth, indicating that changes in soil properties result from both management and the granulometric composition of the soil in different regions of the same watershed. Adoption of crop and pasture conservation practices can improve soil physical attributes in regions bordering agricultural areas in the southern Amazon.

The Teles Pires River basin is experiencing significant water challenges due to recent urban growth, expansion of irrigated agriculture, and the rise of hydroelectric power plants in Brazil’s forest and savanna regions, impacting water availability and sediment production. This study evaluated and estimated the production of suspended sediment (Q_ss) and total sediment (Q_st) in rivers and streams of the Teles Pires River basin, using different sampling methods for suspended-solid discharge: vertical sampling (reference), composite sampling (section), sampling along the standard vertical, and sampling along three verticals, collected using the equal-width increment method. The Q_ss and Q_st values varied from 0.31 to 39.35 metric tons (t) per day (d⁻¹) and from 0.32 to 43.70 t d⁻¹, respectively. The average percentages of the entrained solid discharge varied from 3 to 5%, between the dry and rainy seasons, and across all hydrological sections. The different sampling methods of Q_ss resulted in similar Q_st in each of the monitoring sections. The statistical performance of the simple linear regression model was satisfactory with Willmott index of agreement greater than 0.8234 and 0.9455 for estimates of Q_ss and Q_st, respectively. The dynamics of sediment production and transport was influenced by land use and cover, drainage area, and the hydrological seasonality of the region. The different sampling methods of Q_ss are compatible with obtaining suspended and total solid discharge; however, the standard vertical sampling is the most simplified and can be applied in a hydrological section with uniform hydraulic conditions.

Em função dos avanços dos sistemas de produção agropecuária e da crescente demanda por alimentos no mundo, ainda é proeminente, a necessidade de se investigar as relações existentes entre os atributos do solo e as diferentes condições ambientais em que estão inseridos. Existem diversos produtos científicos que apresentam as caracterizações dos solos brasileiros, contudo, dependendo da aplicação, as maiores limitações estão vinculadas à escalas espaciais e amostragens em regiões isoladas. Neste trabalho é apresentada a classificação dos solos de dezoito perfis, distribuídos em duas bacias hidrográficas (rios Caiabi e Renato) afluentes do rio Teles Pires, no norte de Mato Grosso. Foi realizado o trabalho de campo, com descrição geral e morfológica dos horizontes e coleta de amostras deformadas e indeformadas para análises físicas e químicas em laboratório. A classificação dos 18 perfis de solos em campo foi realizada até o quarto nível categórico. A compatibilidade dos solos classificados em campo com dados disponibilizados pelo IBGE foi de 95% na ordem, 38% na subordem, 95% nos grandes grupos e 88% nos subgrupos. A classe de solo predominante nas duas bacias hidrográficas é dos Latossolos, variando do vermelho a vermelho-amarelo, com matizes de 2,5 YR a 10,0 YR, todos distróficos. Foram observados horizontes plínticos, em posição diagnóstica na bacia do rio Renato e em posições não diagnósticas na bacia do rio Caiabi. Palavras-chave: recursos naturais; Latossolos; pedologia; fronteira agrícola; ecótono Cerrado-Amazônia. Soil classes in the Caiabi and Renato river basins, tributaries of the Teles Pires river, in the south of the Amazon Due to advances in agricultural production systems and the growing demand for food in the world, the need to investigate the relationships between soil attributes and the different environmental conditions in which they are inserted is still prominent. There are several scientific products that present the characterizations of Brazilian soils, however, depending on the application, the greatest limitations are linked to spatial scales and sampling in isolated regions. In this work, eighteen soil profiles were classified, distributed in two hydrographic basins (Renato and Caiabi rivers), of tributaries of the Teles Pires river, in the southern region of the Amazon. Field work was carried out with the general and morphological description of the horizons and the collection of deformed and undisturbed samples for further physical and chemical analysis in the laboratory. The classification of the 18 soil profiles in the field was compared up to the fourth categorical level with the IBGE data, 2021. The compatibility of the soils classified in the field with the IBGE data was 95% in the order, 38% in the suborder, 95% in the large groups and 88% in subgroups. The predominant soil class in the two hydrographic basins is Oxisol (Latosols), ranging from red to red-yellow, with hues from 2.5 YR to 10.0 YR, all dystrophic. Plinthic horizons were observed in diagnostic positions in the Renato river basin and in non-diagnostic positions in the Caiabi river basin. Palavras-chave: natural resource; Oxisol; pedology; agricultural frontier; Cerrado-Amazon ecotone.

Soil water infiltration is an important component of the hydrological cycle, and it is best evaluated when the raindrop impacts the ground surface. For this reason, it is affected by changes in land use and land cover and by the characteristics and physical–hydric properties of the soil. This study aimed to evaluate soil water infiltration in areas occupied by annual crops (soybean and corn) and pastures in two watersheds of the Teles Pires River-MT, using simulated rainfall, physical models, and principal component analysis. Infiltration rates were evaluated based on simulated rainfall with an average intensity of 75 mm h⁻¹, with four repetitions per region (upper, middle, and lower) of the hydrographic sub-basins of the Caiabi and Renato rivers, and soil use with cover, without cover, and disturbed. Soil tillage provided higher water infiltration rates into the soil, especially in pasture areas in the two hydrographic sub-basins. There were significant adjustments to the mathematical models based on the infiltration rate data for all land use and land cover conditions. The soil attributes that most interfered with the infiltration rate were microporosity, bulk density, and total porosity in the crop areas of the middle Caiabi and microporosity, clay content, total porosity, and silt content in the areas farming at the source of the Renato River. The Horton and Philip models presented the best adjustments in the hydrographic sub-basins of the Caiabi and Renato Rivers, which are recommended for estimating the water infiltration rate into the soil in different uses, coverages, and regions.

Mercury (Hg) poses significant risks to human health, the environment, and plant physiology, with its effects influenced by chemical form, concentration, exposure route, and organism vulnerability. This study evaluates the physiological impacts of Hg on Handroanthus impetiginosus (Ipê Roxo) seedlings through SPAD index measurements, chlorophyll fluorescence analysis, and Hg quantification in plant tissues. Four-month-old seedlings were exposed for eight days to distilled water containing Hg at 0, 1, 3, 5, and 7 mg L⁻¹. The SPAD index decreased by 28.17% at 3, 5, and 7 mg L⁻¹, indicating reduced photosynthetic capacity. Chlorophyll a fluorescence analysis revealed a 50.58% decline in maximum efficiency (Fv/Fm) and a 58.33% reduction in quantum yield (ΦPSII) at 7 mg L⁻¹, along with an 83.04% increase in non-photochemical quenching (qn), suggesting oxidative stress and PSII damage. Transpiration decreased by 26.7% at 1 mg L⁻¹ and by 55% at 3, 5, and 7 mg L⁻¹, correlating with Hg levels and leaf senescence. Absorption, translocation, bioconcentration, and bioaccumulation factors varied among treatments. Hg accumulated mainly in stems (40.23 μg g⁻¹), followed by roots (0.77 μg g⁻¹) and leaves (2.69 μg g⁻¹), with limited translocation to leaves. These findings highlight Hg’s harmful effects on H. impetiginosus, an ecologically and commercially valuable species, addressing a gap in research on its Hg tolerance and phytoremediation potential.

Objetivou-se avaliar se níveis de sombreamento afetam as exigências térmicas e o filocrono de mudas de Dipteryx alata, na estação seca da região de transição Cerrado-Amazônia. Foram empregadas telas poliefinas pretas (35; 50; 65 e 80% de sombreamento) e telas coloridas (termorefletora, vermelha, azul e verde, ambas com 50% de sombreamento) e pleno sol (referência). As temperaturas basais foram obtidas por regressões polinomiais entre temperatura do ar no interior dos telados de sombreamento e área foliar total por muda. O filocrono foi obtido por ajustes polinomiais entre o número médio de folhas e de folíolos com a soma térmica acumulada. A temperatura basal máxima e mínima de Dipteryx alata foi de 39,81 e 10,10°C. Não ocorreram diferenças significativas no número de folhas e folíolos, contudo, o incremento do nível de sombreamento aumentou a necessidade de energia térmica para o surgimento de folhas e folíolos (238,96°C.dia-1.folha-1 e 28,40°C.dia-1.folíolo-1) em relação ao pleno sol (166,44°C.dia-1.folha-1 e 17,10°C.dia-1.folíolo-1). Na tela de sombreamento vermelha (50%) ocorreram menores valores de filocrono para a emissão de uma nova folha (147,90°C.dia-1.folha-1) e de folíolo (20,39°C.dia-1.folíolo-1). O surgimento e a expansão foliar de mudas de Dipteryx alata depende da dinâmica microclimática quanti-qualitativa da radiação solar incidente, contudo, a espécie apresenta forte adaptabilidade fenotípica a diferentes condições ambientais. Para aumentar a área foliar e consequentemente a atividade fotossintética da planta, recomenda-se a produção das mudas de Dipteryx alata sob sombreamento, exceto sob a tela azul.