Search Results (116)

The advance of the soil desertification process and water salinisation hinders reforestation actions in the Brazilian semiarid region due to the negative effects on the initial establishment of seedlings. Knowledge of potential species for overcoming the problems of soil and water salinity is of broad interest. This study evaluated the growth of seedlings of the species Handroanthus impetiginosus and Handroanthus spongiosus subjected to the combined stresses of salinity and water deficit. The species were subjected to three water depths (WDs): WD1—50%, WD2—75% and WD3—100% of reference evapotranspiration, and four salinity levels (SL): SL1—0.27 dS m⁻¹, SL2—2.52 dS m⁻¹, SL3—6.35 dS m⁻¹ and SL4—7.38 dS m⁻¹. Biometric data, including plant height, number of leaves, collar diameter and biomass, was obtained. The results showed that H. impetiginosus was more tolerant of the conditions analysed. The species showed greater sensitivity to salt stress, which reduced growth and dry biomass accumulation by up to 98%. Increased water deficit reduced height, collar diameter, number of leaves, root biomass and total biomass. We propose that the optimal water depth for both species is 100% of the reference evapotranspiration. Full article

Passiflora cincinnata (Mast), native to the Brazilian semi-arid region, produces exotic fruits even under low water availability. However, its green coloration at ripening complicates optimal harvesting, impacting post-harvest fruit quality. Therefore, this study aimed to evaluate the influence of cultivation systems (irrigated and rainfed) and different ripening stages on the physical and post-harvest characteristics of wild passion fruit during the second production cycle. The experiment was conducted using a randomized block design in a 2 × 4 factorial scheme, corresponding to two cultivation systems (irrigated and rainfed) and four fruit ripening stages (60, 80, 100, and 120 days after anthesis—DAA), with five replications. The fruit pulps were analyzed for physicochemical characterization and bioactive compounds. The physical and chemical characteristics of wild passion fruit were influenced by ripening stages and the irrigation system. The rainfed system decreased the total fruit mass by 15.50% compared to the irrigated cultivation. Additionally, the rainfed cultivation reduced the fruit color index by 14.82% and altered the respiratory pattern, causing a linear decrease of 73.37% in the respiration rate during ripening, in contrast to the behavior observed in the irrigated system, which reached an estimated minimum rate of 33.74 mg CO₂ kg⁻¹ h⁻¹ at 110 days after anthesis. Full article

Multispectral images obtained from Unmanned Aerial Vehicles (UAVs) have become strategic tools in precision agriculture, particularly for analyzing spatial variability in soil attributes. This study aimed to evaluate the spatial distribution of soil electrical (EC) and total organic carbon (TOC) in irrigated forage cactus areas in the Brazilian semiarid region, using field measurements and UAV-based multispectral imagery. The study was conducted in a communal agricultural settlement located in the Mimoso Alluvial Valley (MAV), where EC and TOC were measured at 96 points, and seven biophysical indices were derived from UAV multispectral imagery. Geostatistical models, including cokriging with spectral indices (NDVI, EVI, GDVI, SAVI, and NDSI), were applied to map soil attributes at different spatial scales. Cokriging improved the spatial prediction of EC and TOC by reducing uncertainty and increasing mapping accuracy. The standard deviation of EC decreased from 1.39 (kriging) to 0.67 (cokriging with EVI), and for TOC from 15.55 to 8.78 (cokriging with NDVI and NDSI), reflecting a 43.5% reduction in uncertainty. The indices, EVI, NDVI, and NDSI, showed strong potential in representing and enhancing the spatial variability in soil attributes. NDVI and NDSI were particularly effective at finer grid resolutions, supporting more efficient irrigation strategies and sustainable agricultural practices. Full article

The Brazilian semi-arid Northeast plays a critical role in regional hydrology, where rainfall is marked by pronounced temporal variability and short duration, presenting significant challenges for understanding and managing hydrological and erosive processes. This study aims to evaluate the performance of empirical models for estimating rainfall kinetic energy (KE) and erosivity index (EI₃₀) in this region, for all events and erosive events, using high-resolution rainfall data collected at the Federal University of Cariri (UFCA), Ceará. A total of 283 natural rainfall events were analyzed, with KE and EI₃₀ values calculated using multiple models: Wischmeier and Smith, USDA, Van Dijk, a temporal variation-based model (KE_VT), and a regional model developed for Brazil’s semi-arid zone, which served as the reference. The results show a predominance of small rainfall events (<5.2 mm), though maximum EI₃₀ values exceeded 1300 MJ ha⁻¹ mm h⁻¹, highlighting the potential for extreme erosive events. Comparative analysis revealed that all international models significantly underestimated KE and EI₃₀ values compared to the regional reference, with the KE_VT model showing the closest approximation (13% underestimation), for all events and erosive events. Statistical assessments using the Wilcoxon test, Nash–Sutcliffe efficiency, and Willmott concordance index confirmed the superior performance of the KE_VT, for all events and erosive events. These findings underscore the importance of considering intra-event rainfall variability and regional calibration when modeling erosivity in semi-arid climates, contributing to more effective soil conservation and hydrological planning. Full article

The increasing resistance of pathogenic microorganisms to antimicrobials has driven the search for safe and sustainable alternatives. In this context, microbial biosurfactants have gained prominence due to their antimicrobial activity, low toxicity, and high stability under extreme conditions. This study presents the production and characterization of a biosurfactant with antimicrobial potential, obtained from Bacillus subtilis isolated from soil, for application in the control of resistant strains. Bacterial identification was performed using mass spectrometry (MALDI-TOF), confirming it as Bacillus subtilis. The strain B. subtilis UCP 1533 was cultivated using different carbon sources (glucose, soybean oil, residual frying oil, and molasses) and nitrogen sources (ammonium chloride, sodium nitrate, urea, and peptone), with evaluations at 72, 96, and 120 h. The best condition involved a mineral medium supplemented with 2% soybean oil and 0.12% corn steep liquor, resulting in the production of 16 g·L⁻¹ of biosurfactant, with a critical micelle concentration (CMC) of 0.3 g·L⁻¹ and a reduction in water surface tension to 25 mN·m⁻¹. The biosurfactant showed an emulsification index of 100% for used motor oil and ranged from 50% to 100% for different vegetable oils, maintaining stability across a wide range of pH, salinity, and temperature. FT-IR and NMR analyses confirmed its lipopeptide nature and anionic charge. Toxicity tests with Tenebrio molitor larvae showed 100% survival at all the tested concentrations. In phytotoxicity assays, seed germination rates above 90% were recorded for Solanum lycopersicum and Lactuca sativa. Antimicrobial tests revealed inhibitory activity against resistant strains of Escherichia coli and Pseudomonas aeruginosa, as well as against species of the genus Candida (C. glabrata, C. lipolytica, C. bombicola, and C. guilliermondii), highlighting the biosurfactant as a promising alternative in combating antimicrobial resistance (AMR). These results indicate the potential application of this biosurfactant in the development of antimicrobial agents for pharmaceutical formulations and sustainable strategies for phytopathogen control in agriculture. Full article

In semi-arid regions, seasonally dry tropical forests are essential for regulating the surface energy balance, which can be analyzed by examining air heating processes and water availability control. The objective of this study was to evaluate the ability of the Brazilian Developments on the Regional Atmospheric Modelling System (BRAMS) model in simulating the seasonal variations of the energy balance components of the Caatinga biome. The surface measurements of meteorological variables, including air temperature and relative humidity, were also examined. To validate the model, we used data collected in situ using an eddy covariance system. In this work, we used the BRAMS model version 5.3 associated with the Joint UK Land Environment Simulator (JULES) version 3.0. The model satisfactorily represented the rainfall regime over the northeast region of Brazil (NEB) during the wet period. In the dry period, however, the coastal rainfall pattern over the NEB region was underestimated. In addition, the results showed that the surface fluxes linked to the energy balance in the Caatinga were impacted by the effects of rainfall seasonality in the region. The assessment of the BRAMS model’s performance demonstrated that it is a reliable tool for studying the dynamics of the dry forest in the region, providing valuable support for sustainable management and conservation efforts. Full article

Forage scarcity, intensified by climate variability and edaphoclimatic limitations in the Brazilian semiarid region, challenges regional livestock production. In this context, forage palm is a strategic alternative due to its drought resistance and environmental adaptability. However, little is known about the spatial and temporal dynamics of its cultivation. This study aimed to characterize the spatio-temporal dynamics of forage palm cultivation in Capoeiras-PE between 2019 and 2022 using remote sensing data and multitemporal analysis of the Normalized Difference Vegetation Index (NDVI), processed via Google Earth Engine. Experimental areas with Opuntia stricta (“Mexican Elephant Ear”) and Nopalea cochenillifera (“Miúda”) were monitored, with field validation and descriptive statistical analysis. NDVI values ranged from −0.27 to 0.93, influenced by rainfall, cultivar morphology, and seasonal conditions. The “Miúda” cultivar showed a lower coefficient of variation (CV%), indicating greater spectral stability, while “Orelha de Elefante Mexicana” was more sensitive to climate and management, showing a higher CV%. Land use and land cover (LULC) analysis indicated increased sparse vegetation and exposed soil, suggesting intensified anthropogenic activity in the Caatinga biome. Reclassified NDVI enabled spatial estimation of forage palm, despite sensor resolution and spectral similarity with other vegetation. The integrated use of satellite data, field validation, and geoprocessing tools proved effective for agricultural monitoring and territorial planning. Full article

Although the NFT (nutrient film technique) solution application rate for cilantro is known for fresh water, the application rate is still debatable when using brackish water. The application rate alone influences flow velocity dynamics, which, when associated with nutrient solution salinity, can impact plant development when saline water is used. Knowledge of how to best combine solution salinity and application rates will help decide if brackish water can be used to produce cilantro under hydroponic conditions. Thus, two trials were conducted in sequence from November 2019 to February 2020 under a protected environment. Cilantro cv. Verdão was submitted to four levels of electrical conductivity of nutrient solutions (ECns of 1.7, 3.0, 4.5, and 6.0 dS m⁻¹) combined with four flow rates (1.0, 2.0, 3.0, and 4.0 L min⁻¹). Because Na⁺ and Ca²⁺ are predominant ions in brackish waters in the crystalline and sedimentary regions in the Brazilian Semiarid region, the first study used brackish waters dominated by NaCl and the second study used waters dominated by CaCl₂. We measured gas exchange and other photosynthetic parameters in plants cultivated with nutrient solutions high in Cl⁻ and prevalent in Na⁺ or Ca²⁺, each combined with different application rates. We concluded that the increment in salinity decreased the gas exchange of cilantro plants, especially when the brackish waters were dominant in Ca²⁺ and Cl⁻. Up to an ECns of 4.5 dS m⁻¹, plants maintained their leaf chlorophyll concentrations, although with reduced gas exchange. Salt stress compromised chlorophyll a fluorescence, affecting important parameters such as initial, maximum, and variable fluorescence. Besides the effects of salinity on chlorophyll a and b concentrations, the quantum and maximum yields of photosystem II remained stable, indicating that photosystem II may have adapted to the saline conditions applied in this study. The variation in application rates was unable to attenuate the deleterious effects of salinity, regardless of the ionic prevalence. We conclude that cilantro plants can be cultivated under hydroponic conditions, using currently accepted flow rates, with nutrient solutions of up to 3.0 dS m⁻¹ without severe damage to plant photosynthetic parameters. Full article

Agroforestry systems (ASs) are increasingly recognized as effective strategies for ecological restoration and sustainable land use in semi-arid regions. This study aimed to evaluate the implementation and early outcomes of an AS established in a degraded urban area in the Brazilian semi-arid region. Specifically, we analyzed the system’s establishment process, estimated its costs, assessed structural development over time, and compared species performance and carbon accumulation across different biodiversity arrangements. After three years, the system accumulated 17.69 Mg ha⁻¹ of carbon and demonstrated significant basal area growth, particularly among fast-growing species such as Ceiba glaziovii, Gliricidia sepium, and Moringa oleifera. These species enhanced overall system productivity and likely contributed to increases in soil organic matter, facilitating the establishment of more demanding, slow-growing species. Cost analysis indicated a total implementation and maintenance estimate of BRL 57,468.79 ha⁻¹ (USD 11,096.29) over three years, with irrigation and maintenance accounting for 44.39%, labor and site preparation 31.59%, and seedling production 24.02%. Although the system proved viable under institutional support, its replicability for smallholders remains dependent on reliable water access or implementation aligned with the rainy season. The use of nursery seedlings enhanced seedling survival and system feasibility. The broader adoption of agroforestry in semi-arid regions will require supportive public policies and technical assistance. Strengthening government programs such as PNAE and PRONAF is essential, as these initiatives can promote system adoption by facilitating access to credit while also reducing costs, particularly when short-cycle crops grown within the system are sold to local schools. It is important to note that agroforestry costs vary depending on the intended objectives, species diversity, and arrangement design. Therefore, technical assistance is critical to guiding smallholders in selecting and implementing context-appropriate systems. Our findings reinforce the potential of agroforestry systems to promote carbon sequestration, restore degraded lands, and support food security and sustainable development in climate-vulnerable regions. Full article

Seasonally dry tropical forests (SDTFs) represent about 41.5% of the planet’s tropical forests. The objective of this study was to characterize the annual mortality and recruitment patterns of stems and trees between the years 2012–2021 in a Caatinga remnant in the state of Pernambuco, Brazil, through geostatistical modeling, and to associate the drought events recorded in the region with vegetation dynamics. Mortality and recruitment of stems and trees were monitored in 80 permanent plots located in an SDTF remnant, counted year by year between 2012 and 2021. The standardized precipitation index (SPI) was calculated to quantify the deficit or excess of rainfall in the evaluated period. The data were then subjected to geostatistical analysis based on the calculation of classical semivariances. As a result, there was a loss of 68.33% of trees and 61.93% of stems in the forest community during 2012–2021, which were associated with the water deficit caused by drought events recorded based on precipitation data and SPI calculation for the region. The Gaussian semivariogram model better represented the spatial variability of mortality and recruitment of stems and trees. An accumulative effect of droughts on increasing mortality rates and reducing recruitment during the study period was observed. The relationship between tree and stem mortality and recruitment rates and drought events highlights the impact of water deficit on vegetation, emphasizing the importance of considering extreme climatic events in the proper management of natural resources. Full article

The Brazilian semiarid region faces water scarcity, with alluvial aquifers playing a crucial role in agricultural water security. This study assesses the spatiotemporal variability of groundwater quantity and salinity, analyzing natural and anthropogenic impacts, including post-pandemic trends. The investigation was developed in the Mimoso Alluvial Valley (MAV), Pernambuco State, mainly used for communal irrigation supply. The spatiotemporal dynamics of land use (LUC) was performed based on data provided by Mapbiomas for the years 2012, 2016, 2019, and 2023. Geostatistical analysis was applied for mapping water table levels and salinity. Changes in LUC suggest possible forest regeneration influenced by climatic factors and anthropogenic pressure alleviation. Electrical conductivity (EC) and groundwater level (GWL) exhibited medium to high variability. Temporal trends highlight climatic influences, groundwater abstraction, and recharge/discharge dynamics. Pre-2019 years were classified as dry, whereas the 2019–2023 years ranged from rainy to extremely rainy, leading to lower EC and GWL variability in 2023. Additionally, the COVID-19 pandemic temporarily reduced agriculture, lowering salinity and aiding groundwater recovery. The spatial analysis revealed critical distribution patterns, highlighting the interaction between natural processes and human activities. These findings provide valuable insights for optimizing irrigation and environmental strategies, supporting long-term groundwater sustainability in semiarid regions. Full article

Water quality affects soils by promoting their degradation by the accumulation of salts that will lead to salinization and sodification. However, the magnitude of these processes varies with soil attributes. Saturated hydraulic conductivity (K_sat) is the rate at which water passes through saturated soil, which is fundamental to determining water movement through the soil profile. The K_sat may differ from soil to soil according to the sodium adsorption ratio (SAR), water electrical conductivity (EC_w), soil texture, and clay mineralogical assemblage. In this study, an experiment with vertical columns and constant-load permeameters was conducted to evaluate changes in soil K_sat with waters comprising five EC_w values (128, 718, 1709, 2865, and 4671 µS cm⁻¹) and five SAR values [0, 5, 12, 20, and 30 (mmol_c L⁻¹)^0.5] in combination. Horizons from nine northeastern Brazilian soils (ranging from tropical to semiarid) were selected according to their texture and clay mineralogical composition. The data obtained were fit with multiple regression equations for K_sat as a function of EC_w and SAR. This study also determined the null SAR at each EC_w level, using K_sat = 0 on each equation, to predict the SAR needed to achieve zero drainage on each soil for each EC_w level and the threshold electrolyte concentration (C_TH) that would lead to a 20% reduction of maximum K_sat. Neither the EC_w nor SAR of the applied waters affected the K_sat of soils with a mineralogical assemblage of oxides and kaolinite such as Ferralsol, Nitisol, and Lixisol, with an average K_sat of 2.75, 6.06, and 3.33 cm h⁻¹, respectively. In smectite- and illite-rich soils, the K_sat increased with higher EC_w levels and decreased with higher SAR levels, especially comparing the soil’s estimated K_sat for water with low EC_w and high SAR in combination (EC_w of 128 µS cm⁻¹ and SAR 30) and water with high EC_w and low SAR in combination (EC_w of 4671 µS cm⁻¹ and SAR 0) such as Regosol (4.95 to 10.94 cm h⁻¹); Vertisol (0.28 to 2.04 cm h⁻¹); Planosol (0 to 0.29 cm h⁻¹); Luvisol (0.46 to 2.12 cm h⁻¹); Cambisol (0 to 0.23 cm h⁻¹); and Fluvisol (1.87 to 3.34 cm h⁻¹). The C_TH was easily reached in soils with high concentrations of highly active clays such as smectites. In sandy soils, the target C_TH was only reached under extremely high SAR values, indicating a greater resistance of these soils to salinization/sodification. Due to their mineralogical assemblage, soils from tropical sub-humid/hot and semiarid climates were more affected by treatments than soils from tropical humid/hot climates, indicating serious risks of physical and chemical degradation. The results showed the importance of monitoring water quality for irrigation, mainly in less weathered, more clayey soils, with high clay activity to minimize the rate of salt accumulation in soils of the Brazilian semiarid region. Our study also proved that clay mineralogy had more influence on the K_sat than clay concentration, mainly in soils irrigated with saline and sodic waters, and that soils with highly active smectite are more prone to degradation than soils with high concentrations of kaolinite. Full article

Projections for the Brazilian semi-arid (BSA) region estimate a reduction in water bodies and an increase in degraded areas. Recovering degraded soils using treated wastewater (TWW) is a strategy to increase the resilience of the local population to these climatic adversities. This study aimed to evaluate the impact of deficit irrigation with treated effluent on the (geo)chemistry of degraded soil in the BSA. An experiment with the application of TWW was conducted on soil degraded within an agroforestry system. The treatments arranged in randomized block design were WS_0.5 (water supply at 0.5 L/plant/week), TE_0.5 (treated effluent at 0.5 L/plant/week), and TE₁ (treated effluent at 1 L/plant/week). Soil samples were collected (0–15 and 15–30 cm) at the initial condition, after two years of irrigation, and two years after the end of irrigation. Analyses of chemicals and geochemicals were carried out. All treatments increased soil fertility after two years in both layers, with TE₁ resulting in higher Ca²⁺ (0–15 cm: 2.88; 15–30; 3.14; cmolc kg⁻¹), Mg²⁺ (0–15 cm: 2.13; 15–30; 2.00; cmolc kg⁻¹), and K⁺ (0–15 cm: 0.11; 15–30; 0.12; cmolc kg⁻¹), generating a residual effect two years post-irrigation suspension and no risk of salinization. However, TE₁ and mainly TE_0.5 showed an increase in sodium content, making the soil solodic (6–11%). The application of TWW changed the CaO, MgO, and K₂O contents of silt fraction, contributing to the availability of Ca, Mg, and K in soils. Future studies should monitor sodium levels and confirm K-bearing phyllosilicate (illitization) after irrigation with TWW. The application of TWW for a short period (two years) and in small volumes (0.5 L/plant/week) affects (geo)chemistry of degraded soil from the BSA. Full article

Reducing losses during pig transport is essential for breeders and transporters, particularly in semi-arid regions, where high temperatures exacerbate transport-related stress and risk of losses. This study aimed to evaluate the effect of transport duration (short vs. long trips) on animal welfare and production losses during the commercial transport of weaner pigs in a semi-arid region. A total of 20 commercial journeys were monitored, with transport times of 30 min (15 km) and 150 min (170 km). Upon arrival, physiological and behavioral stress indicators were assessed in 960 weaner pigs (26.4 ± 2.8 kg body weight, 48 per journey). Production losses were determined by calculating the percentage of injured pigs (NAI), fatigued pigs (NANI), and those that were dead on arrival (DOA), whereas the total loss was expressed by the sum of NAI + NANI + DOA. Weaner pigs transported for 30 min exhibited significantly higher (p < 0.05) rectal temperature, respiratory rate, and stress biomarkers (cortisol and creatine kinase levels). Additionally, this group showed a higher percentage (p < 0.05) of “sitting” pigs and a lower percentage of “lying” pigs in transit, as well as a higher frequency of agonistic behavior after transport compared to those transported for 150 min. Furthermore, higher production losses were recorded in the 30 min transport group, primarily due to the increased percentage of fatigued pigs and DOA pigs. Therefore, shorter transport operations in the Brazilian semi-arid region increased the risk to animal welfare and productive losses, likely due to handling-induced stress during loading. Full article

Phosphorus input into surface water is a global concern due to its role in eutrophication, which is especially critical in semi-arid regions with their challenging climatic conditions. This study evaluated the best model for estimating the phosphorus decay coefficient (k) in semi-arid lakes, using flows from the Soil Moisture Accounting Procedure (SMAP), model of Génie Rural à 4 paramètres Journalier (GR4J), and reverse water balance hydrological models. Conducted at the Orós reservoir with 37 sampling campaigns from 2008 to 2017, it compared decay rates for temperate, tropical, and semi-arid climates. Some analyses also used phosphorus concentrations measured at the reservoir inlet. Model efficiency was assessed with bias, mean relative error, mean squared error, root mean squared error, and standard deviation. from the best models, water quality classes were classified based on phosphorus concentrations with the use of a confusion matrix to calculate accuracy, precision, recall, and F1 score. The findings demonstrated that the decay rate tailored for semi-arid regions, when combined with GR4J flow data, offered the highest accuracy in estimating phosphorus concentrations (bias = 0.0012, RMSE = 0.0326, EMR = 60.6134, STD = 0.0312). In contrast, the decay rate calibrated for tropical conditions with SMAP-derived flows proved superior for classifying water quality categories (classes defined by CONAMA Resolution 357/05). Therefore, the GR4J model for semi-arid conditions stands out for concentration estimation, while the tropical decay rate with SMAP flows is preferable for effective classification of water quality status. Full article