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The South American Monsoon System, which transports moisture from Amazonia to Central-West Brazil, is an important moisture source for the summer rainy season in this region. While local evapotranspiration also contributes to the atmospheric moisture supply, the balance between local and remote sources during the onset of the rainy season remains uncertain. Our research aimed to quantify the role of local evapotranspiration in initiating the rainy season in Central-West Brazil. By utilizing data from various sources, such as remote sensing (MODIS), modern reanalysis (ECMWF's ERA5), and composite products of rainfall (CHIRPS), and analyzing them in a comparative way, we conclusively found that local evapotranspiration is the only relevant source of moisture to the atmosphere during the dry-to-wet season transition, preceding the establishment of the monsoon system. [ABSTRACT FROM AUTHOR]

Despite optical remote sensing (and the spectral vegetation indices) contributions to digital soil-mapping studies of soil organic carbon (SOC), few studies have used active radar remote sensing mission data like that from synthetic aperture radar (SAR) sensors to predict SOC. Bearing in mind the importance of SOC mapping for agricultural, ecological, and climate interests and also the recently developed methods for vegetation monitoring using Sentinel-1 SAR data, in this work, we aimed to take advantage of the high operationality of Sentinel-1 imaging to test the accuracy of SOC prediction at different soil depths using machine learning systems. Using linear, nonlinear, and tree regression-based methods, it was possible to predict the SOC content of soils from western Bahia, Brazil, a region with predominantly sandy soils, using as explanatory variables the SAR vegetation indices. The models fed with SAR sensor polarizations and vegetation indices produced more accurate results for the topsoil layers (0–5 cm and 5–10 cm in depth). In these superficial layers, the models achieved an RMSE in the order of 5.0 g kg−1 and an R2 ranging from 0.16 to 0.24, therefore explaining about 20% of SOC variability using only Sentinel-1 predictors. [ABSTRACT FROM AUTHOR]

The water crisis is a reality in Western Bahia. In this region, a hydroclimatic monitoring system capable of providing water availability information in advance for water users was implemented objectively to avoid water conflicts. In this study, we proposed the integration between the hydroclimatic monitoring system and a linear programming method to optimize the agricultural net benefit considering the scenarios of rainfall delay or reduction. Case studies were demonstrated in five farms and three municipalities of Western Bahia. The results show that in irrigated areas, the model optimizes the net economic benefit by the possibility of a continuous or double-cropping system, even in rainfall delay or reduction, where irrigation can supply the water demand of crops. In rainfed areas, it is noticeable that in rainfall delay or reduction scenarios, the model response is not to crop, due to the accentuated water deficit in crops, which may cause a significant yield reduction. It was found in a farm-level analysis, where the model response was not to crop, and farmers had a yield reduction of 61% in rainfed areas. This study opens the integration between the optimization methodologies and the hydroclimatic monitoring system with new insights into how this integration can guide water governance actions in regions where the water crisis is a reality. [ABSTRACT FROM AUTHOR]

Western Bahia is a critical region in Brazil's recent expansion of agricultural output. Its outstanding increase in production is associated with strong growth in cropland area and irrigation. Here we present analyses of Western Bahian historical changes in land use, including irrigated area, and suitability for future agricultural expansion that respects permanent protection areas and the limits established by the Brazilian Forest Code in the Cerrado biome. For this purpose, we developed a land use and land cover classification database using a random forest classifier and Landsat images. A spatial multicriteria decision analysis to evaluate land suitability was performed by combining this database with precipitation and slope data. We demonstrate that between 1990 and 2020, the region's total agricultural area increased by 3.17 Mha and the irrigated area increased by 193,480 ha. Throughout the region, the transition between the different classes of land use and land cover followed different pathways and was strongly influenced by land suitability and also appears to be influenced by Brazil's new Forest Code of 2012. We conclude that even if conservation restrictions are considered, agricultural area could nearly double in the region, with expansion possible mostly in areas we classify as moderately suitable for agriculture, which are subject to climate hazards when used for rainfed crops but are otherwise fine for pastures and irrigated croplands. [ABSTRACT FROM AUTHOR]

Western Bahia, part of a large Brazilian agricultural frontier, is located mainly in fragile, sandy soils in a tropical seasonal climate with dry winters, characteristics that facilitate soil carbon loss. This study evaluates whether rainfed and irrigated agriculture in Western Bahia were able to sequester carbon and re-establish the soil organic carbon content (SOCC) lost due to land use change. Between 2010 and 2018, a total of 5469 soil samples were collected in the 0.00–0.20 m soil layer from nine farms and were used to calculate the annual rate of SOCC variation. The most recent SOCC measured in plots where land use change occurred 20 years ago was compared with the SOCC measured in areas of native vegetation (Cerrado). Results showed that (i) irrigated sandy agricultural lands replenished SOCC to the level observed in native vegetation by 20 years after a land use change event and are still capturing carbon at a significant rate, (ii) clayey, rainfed agricultural lands also sequester carbon, but these soils are not representative of the region, and (iii) sandy, rainfed agricultural lands, the predominant soil type and management practice in Western Bahia, are not a sink of CO2. [ABSTRACT FROM AUTHOR]

In Western Bahia, one of the most active agricultural frontiers of the world, cropland area and irrigated area are increasing at fast rates, and water conflicts have been happening at least since 2010. This study makes a hydroclimatic analysis of the water resources in Western Bahia, from both supply and demand viewpoints. Time series of precipitation for the period 1980–2015 and river discharge for the period 1978–2015 are analyzed, indicating a significant reduction of up to 12% in rainfall since the 1980s, and a reduction in river discharge in all stations studied, in both the rainy season and the dry season. Combined with that, irrigated area has increased over 150-fold in 30 years, and in the most irrigated regions, has increased by 90% in the last eight years only. Seven regions in Western Bahia have been identified where the potential for water use conflicts is critical. Moreover, the combination of reduced availability and increased demand of water resources indicates that, if current trends are maintained, conflicts over water may become more frequent in the next years or decades. A short-term alternative to avoid such conflicts is to largely avoid irrigation during the months with low discharge. However, a monitoring system in which the availability and demand of water resources for irrigation are actually measured and monitored, is the safest path to provide water security to this region. [ABSTRACT FROM AUTHOR]

Western Bahia is one of the most active agricultural frontiers in the world, which raises concern about its natural resources conservation, especially regarding water availability. This study evaluated the influence of five different land uses and land covers on physical and hydraulic soil properties, and developed pedotransfer functions to derive regional hydraulic properties. Significant changes between physical and hydraulic soil properties under agricultural areas and under natural vegetation cover were found, reinforcing that agricultural activity may influence the soil water balance. Cerrado and Forest formation areas have higher infiltration rates ( K s a t ) compared to managed areas, with average values of 16.29 cm h−1, and 14.47 cm h−1, while irrigated croplands, rainfed croplands and pasture areas have much smaller infiltration rates, with K s a t equal to 3.01 cm h−1, 6.22 cm h−1 and 5.01 cm h−1, respectively. Our results suggest that the agriculture practices do not directly affect the vertical nature of hydrological flowpath, except in the case of intensive irrigated agriculture areas, where K s a t reduction can lead to erosive processes favoring organic matter losses, and decreases in productivity and soil quality. Impacts of land use change on hydraulic and physical soil properties are a reality in the Cerrado agriculture frontier and there is an urgent need to monitor how these changes occur over time to develop effective mitigation strategies of soil and water conservation. [ABSTRACT FROM AUTHOR]

This study investigated the influence of large slaughterhouses on five variables, two related to environment impact (land use change rate and greenhouse gases emissions (GE)), and three related to cattle-ranching intensification (protein from crops, calories from crops and stocking rate). In Amazonia, the results show a reduction of the land use change rate and GE in zones both with and without the influence of large slaughterhouses. The hypothesis that slaughterhouses are leverage points to reduce deforestation in the biome was not confirmed. The slaughterhouses also seem to have no effect on cattle ranching intensification, as protein and calories production increased significantly in both zones, while the stocking rates did not change in the influence zones. In the Cerrado, cattle-ranching intensification is a reality, and is occurring independently of the presence of large slaughterhouses. In conclusion, the results show no evidence that large slaughterhouses have promoted either cattle-ranching intensification or improvements in the sustainability of the cattle-ranching activity in Amazonia and the Cerrado. [ABSTRACT FROM AUTHOR]