Fractal features of soil texture and physical attributes in indian dark earth under different uses in Western Amazon

Studying particle size distribution is important to understand soil structure and formation processes. This research aimed to assess the fractal dimension of soil texture in Indian Dark Earth (IDE) areas in southern Amazonas state under different land uses, as follows: two areas in the municipality of Apuí, one growing cocoa and the other coffee; a grassland area in the municipality of Manicoré; and a forest area in the municipality of Novo Aripuanã. A sampling grid containing 88 collection points (intersecting points on the grid) was established in each area, measuring 80 x 42 m for the cocoa and coffee-growing sites, and 80 x 56 m and 60 x 42 m for the grassland and forest areas, respectively. Soil samples were collected in soil core and as clumps at a depth of 0.0-0.20m to determine the structural physical properties and texture of the soil. The following physical attributes were assessed: texture (PSD), bulk density (BD), macroporosity (Macro), microporosity (Micro), total porosity (TP) and aggregate stability (GMD and WMD). The fractal dimension (D) of the soil texture was determined, followed by analysis of variance and comparison of the means using Tukey’s test (p≤0.05). Pearson’s correlation was applied to assess the correlation between variables. There was a significant difference between the IDEs studied, with a higher D value in the cocoa-growing area in relation to the other sites. Additionally, the larger the clay fraction, the higher the D value. Fractal dimension (D) showed a positive correlation with sand, clay, BD, Macro, GMD and WMD, and a negative correlation with silt, micro, TP. Based on the D values obtained, the ADE cultivated with cocoa showed superior quality in relation to the other areas studied

Eficiência fotoquímica de porta-enxertos de cajueiro sob estresse salino e aplicação foliar de silicato de potássio

The cashew tree is one of the most economically important fruit trees in Brazil, especially in the Northeast region. However, abiotic factors such as the salinity of water and soils in this region stand out as a limiting factor for this crop, affecting all stages of development, as well as physiological and biochemical processes. Therefore, the use of products that mitigate such damage becomes necessary, with silicon and potassium as a viable alternative. Thus, the objective of this work was to evaluate the photochemical efficiency of cashew tree rootstock subjected to water salinity and foliar potassium silicate application. A randomized block design, distributed in a 5x5 factorial scheme, with four replications and two plants per plot, was used, the treatments being by conductivity of the irrigation water - CEa (0.3, 1, 1.7, 2.4 and 3.1 dS m-1) and potassium silicate concentrations (0, 250, 500, 750 and 1000 mg L-1) applied via the leaves. The salinity of irrigation water causes reductions in the photochemical efficiency of photosystem II and, consequently, in the photosynthetic apparatus of cashew plants, 70 days after sowing. The concentration of 250 mg L-1 of potassium silicate promotes an increase in the quantum yield of cashew plants under salt stress conditions.  O cajueiro é uma das frutíferas de maior importância econômica no Brasil, especialmente na região Nordeste. Porém, fatores abióticos como a salinidade da água e dos solos dessa região destaca-se como fator limitante para essa cultura, afetando em todas as fases de desenvolvimento, bem como nos processos fisiológicos e bioquímicos. Diante disso, o uso de produtos que amenize tais danos, torna-se necessário, tendo no silício e potássio uma alternativa viável. Assim, o objetivo deste trabalho foi avaliar a eficiência fotoquímica de porta-enxerto de cajueiro submetido à salinidade da água e aplicação de silicato de potássio foliar. Utilizou-se o delineamento de blocos casualizados, distribuído em esquema fatorial 5x5, com quatro repetições e duas plantas por parcela, sendo os tratamentos por condutividade da água de irrigação - CEa (0,3, 1, 1,7, 2,4 e 3,1 dS m-1) e concentrações de silicato de potássio (0, 250, 500, 750 e 1000 mg L-1) aplicadas via foliar. A salinidade da água de irrigação ocasiona reduções na eficiência fotoquímica do fotossistema II e consequentemente, no aparato fotossintético de plantas de cajueiro, aos 70 dias após a semeadura. A concentração de 250 mg L-1 de silicato de potássio promove aumento no rendimento quântico de plantas de cajueiro em condições de estresse salino

Heavy metals in waters used for human consumption and crop irrigation

The consumption of contaminated water is a major source of heavy metal contamination in humans and animals. This study therefore aimed to assess Cd, Cu, Mn, Ni, Pb, and Zn levels in water used for human and animal consumption and vegetable crop irrigation in Camocim de São Félix, Pernambuco, Brazil. Water samples were collected on the studied farms from an artesian well and reservoirs used for human and animal consumption as well as for crop irrigation. The results showed that concentrations of Cd (> 0.001 mg L-1), Ni (> 0.025 mg L-1) and Pb (> 0.01 mg L-1) were above the maximum allowable limits established under Brazilian law, indicating the need for a preventive monitoring program and immediate intervention initiatives aimed at the sources of contamination. The results demonstrate the need to quantify heavy metal content in vegetable crops, since their contamination by irrigation water may make them harmful to human health. Rainfall has a seasonal effect on heavy metal concentrations in water, showing a significant effect on Pb levels, whereas Cd and Ni content was less dependent on seasonal variation

Heavy metals in waters used for human consumption and crop irrigation

<div><p>Abstract The consumption of contaminated water is a major source of heavy metal contamination in humans and animals. This study therefore aimed to assess Cd, Cu, Mn, Ni, Pb, and Zn levels in water used for human and animal consumption and vegetable crop irrigation in Camocim de São Félix, Pernambuco, Brazil. Water samples were collected on the studied farms from an artesian well and reservoirs used for human and animal consumption as well as for crop irrigation. The results showed that concentrations of Cd (> 0.001 mg L-1), Ni (> 0.025 mg L-1) and Pb (> 0.01 mg L-1) were above the maximum allowable limits established under Brazilian law, indicating the need for a preventive monitoring program and immediate intervention initiatives aimed at the sources of contamination. The results demonstrate the need to quantify heavy metal content in vegetable crops, since their contamination by irrigation water may make them harmful to human health. Rainfall has a seasonal effect on heavy metal concentrations in water, showing a significant effect on Pb levels, whereas Cd and Ni content was less dependent on seasonal variation.</p></div