Brazilian Tropical Savanna Research Articles

Spatio-Temporal Dynamics of Center Pivot Irrigation Systems in the Brazilian Tropical Savanna (1985–2020)

The 204-million-hectare Brazilian tropical savanna (Cerrado biome), located in the central part of Brazil, constitutes the main region of food and natural fiber production in the country. An important part of this production is based on center pivot irrigation. Existing studies evaluating the spatio-temporal dynamics of center pivots in Brazil do not consider their retraction. This study aimed to evaluate the expansion and retraction of center pivots in the Cerrado biome in the period 1985–2020. We relied on the data produced by the MapBiomas Irriga project. In this period, the area occupied by center pivots increased from 47 thousand hectares in 1985 to 1.2 million hectares in 2020, mostly concentrated in the states of Minas Gerais, Goiás, São Paulo, and Bahia, confirming previous reports available in the literature. Among the 13 irrigation poles recognized by the National Water Agency (ANA), the Oeste Baiano (Bahia State) and the São Marcos (Goiás State) presented the largest areas of center pivots (173,048 ha and 101,725 ha, respectively). We also found that 76% of the center pivots are concentrated in the regions with low water availability (0.01–0.45 mm day−1). Within this 16-year period (2005–2020), more than 10% of center pivots found in 2005 were either abandoned or converted into rain-fed crop production. The results of this study can provide an important foundation for public policies directed toward the sustainable use of water resources by different consumers.

Flowering Time Variation in Two Sympatric Tree Species Contributes to Avoid Competition for Pollinator Services.

Competition is an important biological filter that can define crucial features of species' natural history, like survival and reproduction success. We evaluated in the Brazilian tropical savanna whether two sympatric and congenereric species, Qualea multiflora Mart. and Q. parviflora Mart. (Vochysiaceae), compete for pollinator services, testing whether there is a better competitor or whether plants present any anti-competitive mechanism. Additionally, we investigated the breeding system, pollinators, and flowering phenology of both species. The results showed that Q. multiflora and Q. parviflora are dependent on pollinators for fruit formation, as they exhibited a self-incompatible and non-agamospermic breeding system. These plants shared the same guild of pollinators, which was formed by bees and hummingbirds, and an overlap in the flower visitation time was observed. Each plant species had different pollinator attraction strategies: Q. multiflora invested in floral resource quality, while Q. parviflora invested in resource quantity. The blooming time showed a temporal flowering partition, with highly sequential flowering and no overlap. Qualea parviflora bloomed intensely from September to October, while Q. multiflora bloomed from November to January, with the flowering peak occurring in December. The two Qualea species have morphologically similar flowers, are sympatric, and share the same pollinator community, with overlapping foraging activity during the day. However, they do not compete for pollinator services as they exhibit an anti-competitive mechanism mediated by temporal flowering partition.

Evaluation and Modelling of Reference Evapotranspiration Using Different Machine Learning Techniques for a Brazilian Tropical Savanna

Meteorological elements can affect the environment and cultures differently and may alter the natural development process contributing significantly to climate change. Meteorological variables of the Brazilian Pantanal were studied and used to determine evapotranspiration with fewer variables. It was found that artificial intelligence can substantially improve environmental modeling when alternative prediction techniques are used, resulting in lower project costs and more reliable results. This work tried to find the best combination by comparing machine learning techniques such as artificial neural networks, random forests, and support vector machines. A new model was created that depends on fewer climatic variables compared to the Penman–Monteith method (the standard method for estimating reference evapotranspiration) and can efficiently describe the reference evapotranspiration. Machine learning techniques are highly efficient for modeling environmental systems since they can process large amounts of data and find the best interactions between the parameters involved. In addition, more than 98% accuracy was obtained using fewer variables compared to the standard method when artificial neural networks are utilized.

Mixtures of grasses: An alternative to traditional pasture monocultures in the tropics

AbstractA two‐year experiment assessed herbage production and above‐ and below‐ground characteristics of a highly productive monoculture (‘BRS Zuri’ guineagrass [Panicum maximum Jacq.]) and two mixtures of three grasses (Mixture 1: ‘BRS Zuri’ guineagrass, ‘BRS Xaraés’ palisadegrass [Brachiaria brizantha Stapf.], and ‘Basilisk’ signalgrass [Brachiaria decumbens Stapf.]; Mixture 2: ‘BRS Quênia’ guineagrass [Panicum maximum Jacq.], ‘Marandu’ palisadegrass [Brachiaria brizantha Stapf.], and ‘BRS Paiaguás’ palisadegrass [Brachiaria brizantha Stapf.]), cultivated in the Brazilian tropical savanna. Mixtures 1 and 2 were subjected to two grazing intensities (removal of 40 or 60% of pre‐grazing height) and ‘BRS Zuri’ guineagrass monoculture was defoliated to a single grazing intensity of 50%. Treatments were randomly assigned to fifteen 0.25‐ha plots and managed under intermittent stocking by cattle. Herbage accumulation rate was similar among pastures and years (p > .1). The root mass in the tussocks did not differ (p > .1), with mean values ranging between 0.62 to 1.81 kg DM m−2. Root density in the tussock interspaces was greater in the mixtures (p < .001), regardless of seasons (p = .405) and years (p = .292). The mixtures were dominated by guineagrass (70%) and palisadegrass (30%) at the end of the experiment, with the population of ‘Basilisk’ and ‘BRS Paiaguás’ being completely suppressed throughout the experimental period. Mixing guineagrass and brachiariagrasses can be an alternative to the traditional pastoral systems in the tropics, as it does not compromise herbage production and presents a capacity to produce more roots than a very productive monoculture of ‘BRS Zuri’ guineagrass.

Nitrogen and phosphorus pools and fluxes in upland and seasonally flooded forests and woodlands of the Cerrado-Pantanal transition of Brazil

Brazilian tropical savanna (referred to as Cerrado) has enormous structural variability ranging from tree- and shrub-free grasslands to tall, dense forests that are found in both well-drained upland and seasonally flooded (hyperseasonal) landforms. These structural and hydrological variations cause variations in aboveground carbon (C) storage, and presumably nitrogen (N) and phosphorus (P) storage and fluxes; however, the effects of these structural and hydrological variations on ecosystem N and P pools and fluxes are less well-known. Thus, our objective was to analyze N and P pools and fluxes for a spectrum of Cerrado physiognomies in both upland and hyperseasonal landforms. N and P pools and fluxes were compiled over an 8-10 year period in structurally different forms of Cerrado, including both upland and hyperseasonal grass dominated (campo sujo), typical wooded (sensu stricto) and dense wooded cerrado, and forested Cerrado stands located in the Cuiaba Basin and Northern Pantanal of southern Mato Grosso, Brazil. We found that aboveground N and P storage was generally higher in forested Cerrado than in non-forest landcover types, regardless of hydrology; however, these patterns were not consistent as wood N and P storage was just as high in typical- and dense-wooded savanna as in forested savannas. Wood typically made up the largest aboveground vegetation N and P reservoir, even for woody-grass savanna (campo sujo) which had a substantially lower tree density than wooded or forested savanna, followed by litter and roots, and then foliage. However, the vast majority of N and P was found in the upper 50 cm soil layer, accounting for 82-98% and 72-98% of the total ecosystem N and P, respectively, and even if only the 0-10 cm soil layer is considered, more than half of the ecosystem N and P was found in soil. Nutrient return via litter production was the largest flux followed by mineralization and root uptake, and nutrient cycling in litter production tended to be higher for forests than for wooded and woody-grass savannas. Savanna woodlands and forests in the Pantanal had higher N and P storage than comparable woodlands and forests in the Cuiaba Basin, presumably because of the shallower and stonier soils of the Cuiaba Basin. However, while the vegetation types studied here had large differences in structure (vegetation height, leaf area index, and density), the forested and wooded savannas had comparable belowground and wood N and P pools.

Net Primary Production and Ecosystem Carbon Flux of Brazilian Tropical Savanna Ecosystems From Eddy Covariance and Inventory Methods

AbstractEstimates of net primary (NPP) and ecosystem production (NEP) are needed for tropical savanna, which is structurally diverse but understudied compared to tropical rainforest. We used eddy covariance and inventory methods to estimate carbon (C) fluxes for an upland mixed grassland and a seasonally flooded forest to determine the correspondence between these methods and assess the contribution of C cycling components to the total NPP. Both techniques provided similar estimates of net ecosystem CO2 exchange (−3.0 ‒ 2.3 MgC ha−1 y−1 for eddy covariance vs. −2.0 ‒ 4.3 MgC ha−1 y−1 for inventory), gross primary production (7.5–16.3 MgC ha−1 y−1 for eddy covariance vs. 8.7–18.4 MgC ha−1 y−1 for inventory), and total NPP (0.9–7.5 MgC ha−1 y−1 for eddy covariance vs. 2.0–9.5 MgC ha−1 y−1 for inventory). Belowground NPP accounted for 49%–53% of the total NPP for both ecosystems, followed by aboveground litter (26%–27%) and wood (16%–17%) production. Increases in water availability increased the potential for C storage, but the mechanism was different in the savanna types. Compared to other savanna ecosystems, the mixed grassland had a lower productivity and C use efficiency (CUE = NPP/GPP = 0.28), while the Cerrado forest had a high CUE (0.58) and similar C flux rates to other tropical savanna forests. The agreement in the C cycle estimates derived from the eddy covariance and inventory methods increases our confidence in the productivity estimates for these tropical savanna ecosystems.

Quantifying the climate change‐driven impacts on the hydrology of a data‐scarce watershed located in the Brazilian Tropical Savanna

AbstractTropical savannas are one of the most affected biomes worldwide by anthropogenic activities. The Cerrado biome, also referred to as the Brazilian Tropical Savanna, is one of the world's environmental hotspots due to its high biodiversity and endemism. Also, it is essential for water resources in South America and hydropower generation in Brazil. In this context, this study aimed to evaluate possible changes in water availability in the Cerrado due to the impacts of climate change throughout the 21st century under different emissions scenarios. The Soil and Water Assessment Tool (SWAT) was calibrated and validated in a watershed encompassing 51 237 km2. The regional climate models (RCMs) Eta‐HadGEM‐ES and Eta‐MIROC5 under the representative concentration pathways (RCPs) 4.5 and 8.5 were used to simulate the streamflow changes in three time slices (2010–2040, 2041–2070, and 2071–2099). The streamflow can be reduced by up to 70%, being Eta/HadGEM2‐ES RCM under RCP 8.5 projected the most severe impact. On average, the most significant runoff reductions occurred in the first and third time slice (−54.51%). Baseflow and evapotranspiration can reduce up to 55% and 23%, respectively, at the end of the century. In addition, the hydrological drought assessment stressed the higher frequency of severe drought events in the first time slice. Streamflow regularization can be an alternative to mitigate the impacts of climate change in the Brazilian Tropical Savanna throughout the 21st century.

Do natural ecosystems differ in terms of some soil physical properties? Savanna vs native grassland

While numerous studies demonstrated the reduction effect of infiltration changes with natural vegetation conversion to croplands, few information is available examining inherent differences between natural ecosystems. We examined the steady state infiltration rate and other topsoil properties in two adjacent native ecosystem types (of the Brazilian tropical savanna) occurring under a similar soil type (oxisol), a native grassland and a savanna. We found a significantly higher steady state infiltration rate in the savanna (698 ± 521 mm h−1) compared to native grassland (413 ± 181 mm h−1). All soil properties were significantly different when comparing both ecosystem types indicating that higher topsoil permeability in the savanna is potentially related to higher organic matter content, lower bulk density, and lower penetration resistance. Previous studies have documented differences in soil hydraulic properties between natural and anthropogenic ecosystems under a similar soil type. Here we showed that such differences can also occur among natural ecosystems.

Multiple cues guarantee successful predation by a Neotropical wasp

Abstract Predatory social wasps are well studied in several aspects; however, foraging behaviour, especially that which takes place away from the nest at often unpredictable locations, or specialized behaviours to find and subdue prey are not well understood. In the Brazilian tropical savanna, the Polistinae wasp Brachygastra lecheguana is specialized in preying on some endophytic weevil larvae which develops inside floral buds. We hypothesized that these wasps utilize a combination of different mechanisms such as visual, chemical (odour) and possible tactile cues to find the weevil larvae. Using a combination of experimental manipulations (visual; chemical; visual/chemical) we tested the wasp’s ability to detect the endophytic larvae in the field. Additionally, we checked the ability of this wasp to detect vibrations produced by the weevils inside the buds. Our results suggest that the B. lecheguana wasp utilizes a sequence of eco-physiological mechanisms to find the endophytic larva inside floral buds: sight, smell, and perhaps touch. The use of multiple cues by this wasp guarantees such a high rate of predation on endophytic beetles that the wasp may have positive implications (reduction in weevils’ infestation) for the future of the host plant’s reproduction.

Visual cues do not increase artificial nest predation in a Brazilian tropical savanna

Visual cues do not increase artificial nest predation in a Brazilian tropical savanna

Large scale multi-layer fuel load characterization in tropical savanna using GEDI spaceborne lidar data

Quantifying fuel load over large areas is essential to support integrated fire management initiatives in fire-prone regions to preserve carbon stock, biodiversity and ecosystem functioning. It also allows a better understanding of global climate regulation as a potential carbon sink or source. Large area assessments usually require data from spaceborne remote sensors, but most of them cannot measure the vertical variability of vegetation structure, which is required for accurately measuring fuel loads and defining management interventions. The recently launched NASA's Global Ecosystem Dynamics Investigation (GEDI) full-waveform lidar sensor holds potential to meet this demand. However, its capability for estimating fuel load has yet not been evaluated. In this study, we developed a novel framework and tested machine learning models for predicting multi-layer fuel load in the Brazilian tropical savanna (i.e., Cerrado biome) using GEDI data. First, lidar data were collected using an unnamed aerial vehicle (UAV). The flights were conducted over selected sample plots in distinct Cerrado vegetation formations (i.e., grassland, savanna, forest) where field measurements were conducted to determine the load of surface, herbaceous, shrubs and small trees, woody fuels and the total fuel load. Subsequently, GEDI-like full-waveforms were simulated from the high-density UAV-lidar 3-D point clouds from which vegetation structure metrics were calculated and correlated to field-derived fuel load components using Random Forest models. From these models, we generate fuel load maps for the entire Cerrado using all on-orbit available GEDI data. Overall, the models had better performance for woody fuels and total fuel loads (R2 = 0.88 and 0.71, respectively). For components at the lower stratum, models had moderate to low performance (R2 between 0.15 and 0.46) but still showed reliable results. The presented framework can be extended to other fire-prone regions where accurate measurements of fuel components are needed. We hope this study will contribute to the expansion of spaceborne lidar applications for integrated fire management activities and supporting carbon monitoring initiatives in tropical savannas worldwide.

Implementation of Fire Policies in Brazil: An Assessment of Fire Dynamics in Brazilian Savanna

In 2012, the Brazilian government implemented the Federal Brigades Program (FBP), a fire policy strategy to hire and train firefighters to combat wildfires. This study analyzed the impact of this program on fire behavior before (2008–2012) and after (2013–2017) its implementation in the Parque do Araguaia Indigenous Land, the largest indigenous territory with the highest occurrence of fires in the Brazilian tropical savanna. We analyzed the annual pattern of fire incidence in the dry season, the fire impact per vegetation type, the recurrence, and the relationship between fire and precipitation. The datasets were based on active fire products derived from the Moderate Resolution Imaging Spectroradiometer (MODIS), the Landsat and Resourcesat-based burned area products, and the records of the fire combat operations. Our results showed that FBP contributed to the reduction of the number of areas affected by fires and to the formation of a more heterogeneous environment composed of fire-resistant and fire-sensitive native vegetation fragments. On the other hand, after the implementation of the FBP, there was an increase in the recurrence of 3–4 years of fires. We concluded that the FBP is an important public policy capable of providing improvements in fire management activities.

Production of microbial carotenoids by Rhodotorula lactosa isolated in the Brazilian tropical savanna / Produção de carotenoides microbianos por Rhodotorula lactosa isolada na savana tropical brasileira

Exploration of new biomes to obtain microorganisms of industrial interest can reveal a number of new strains but they are not all equally efficient in their carotenoids production under different environmental conditions. Screening is needed to select the elite strain and thus commercially produce the pigment. The main objective of this study was to increase the carotenoid production capacity of a recently isolated yeast obtained from the Cerrado (Brazilian tropical savanna) biome. Four hundred and seventy yeast colonies were isolated, of which 25 were pigment-producing yeasts. The promising yeast was identified, by molecular analysis (polymerase chain reaction - PCR) as Rhodotorula lactose, presenting 4.0 g/L of biomass and 776.67 µg/L (194.17 µg/g) of carotenoids (volumetric and specific) in the commercial medium. In the optimization, the carbon source (43 g/L of glucose) was the most significant and positive factor in the carotenoid production process (1318.27 µg/L and 145.58 µg/g), followed by the concentration of nitrogen sources (0.7 g/L yeast extract and 0.7 g/L peptone). The equation generated from the optimized process was validated and showed similar values in the carotenoid production (1233.80 µg/L and 156.60 µg/g) proving it to be promising process model for a scale-up using submerged culture.

Evaluation of FAO-56 Procedures for Estimating Reference Evapotranspiration Using Missing Climatic Data for a Brazilian Tropical Savanna

The Brazilian savanna (Cerrado) has been heavily impacted by agricultural activities over the last four to five decades, and reliable estimates of reference evapotranspiration (ETo) are needed for water resource management and irrigation agriculture. The Penman–Monteith (PM) is one of the most accepted models for ETo estimation, but it requires many inputs that are not commonly available. Therefore, assessing the FAO guidelines to compute ETo when meteorological data are missing could lead to a better understanding of which variables are critically important for reliable estimates of ETo and how climatic variables are related to water requirements and atmospheric demands. In this study, ETo was computed for a grass-dominated part of the Cerrado from April 2010 to August 2019. We tested 12 different scenarios considering radiation, relative humidity, and/or wind speed as missing climatic data using guidelines given by the FAO. Our results presented that wind speed and actual vapor pressure do not affect ETo estimates as much as the other climatic variables; therefore, in the Cerrado’s conditions, wind speed and relative humidity measurements are less required than temperature and radiation data. When radiation data were missing, the computed ETo was overestimated compared to the benchmark. FAO procedures to estimate the net radiation presented good results during the wet season; however, during the dry season, their results were overestimated because the method could not estimate negative Rn. Our results indicate that radiation data have the highest impact on ETo for our study area and presumably for regions with similar climatic conditions. In addition, those FAO procedures for estimating radiation are not suitable when radiation data are missing.

Water Appropriation on the Agricultural Frontier in Western Bahia and Its Contribution to Streamflow Reduction: Revisiting the Debate in the Brazilian Cerrado

Over the last three decades, almost half of the Brazilian tropical savanna (Cerrado biome) has been converted into cropland and planted pastures. This study aims to understand the implications of the expansion of the agricultural frontier for water resources in western Bahia state. We use an interdisciplinary approach that combines quantitative and qualitative data (spatial and hydrological analysis, interviews) to tie together land use changes in the Corrente basin, the streamflow and precipitation time series in the Pratudão River sub-basin (part of the Corrente basin), and the perceptions of soybean farmers and smallholder communities about the transformations of the hydrological cycle over the last few years. We observed an almost 10-fold increase in agricultural surface area in the Corrente River basin over the last three decades (1986–2018), going on from 57,090 ha to 565,084 ha, while center-pivot irrigated areas increased from 240 ha to 43,631 ha. Over this period, the streamflow has reduced by 38% in the Pratudão River. Our hydrological analyses, based on the Mann-Kendall test, of seven fluviometric stations and 14 pluviometry stations showed a statistically significant streamflow trend in the Pratudão River sub-basin for both minimum and mean streamflow series (p ≤0.05). Surface runoff coefficient, which relates streamflow and precipitation annual data coefficient, decreased from around 0.4 in the late 1990s to less than 0.2 in 2015. In addition, most precipitation time series analysis (number of annual rainy days) showed no statistically significant trend (p > 0.05). Our results indicate that agricultural changes rather than climate change may be the main driver of downward streamflow trends in the Pratudão River sub-basin that is part of Corrente River basin.

Water infiltration in the domains of the Brazilian Tropical Savanna: what do we really know?

Water infiltration is a key process in groundwater-river recharge. However, it is poorly known in the Brazilian Tropical Savanna (biome with different natural ecosystems, such as savannas, native grasslands, and forests). Thus, we carried out a review on soil water infiltration in different natural ecosystem types within the domains of the Brazilian Tropical Savanna. We collected articles from the Web of Science, Periódicos CAPES, and Scholar Google databases. We found 15 articles (including 22 assays) with studies prevailing in the Midwest region of Brazil. The mean and median infiltration capacity of all studies was 792 and 567 mm h-1, respectively. The majority of the studies (12 articles) did not clearly define which specific type of ecosystem was studied. Furthermore, most of the studies were carried out in Oxisols. Generally, the studies had a low sample size to characterize soil properties. A better description of ecosystem type, as well as a more significant sample size, are needed to understand infiltration in natural ecosystems of the Brazilian Tropical Savanna. Given the limitations of the studies available, our review showed that it is still too early to synthesize and to make an in-depth discussion on such topic in such huge and heterogeneous biome. Infiltração de água nos domínios da Savana Tropical Brasileira: o que realmente sabemos? R E S U M OA infiltração de água é um processo chave na recarga de rios e aquíferos. Entretanto, é pouco conhecido no Cerrado brasileiro (bioma com diferentes ecossistemas naturais, tais como as formações savânicas, campestres e florestais). Assim, realizou-se uma revisão sobre a infiltração de água no solo em diferentes tipos de ecossistemas dentro dos domínios do Cerrado brasileiro. Os artigos coletados foram das bases de dados Web of Science, Periódicos CAPES e Google escolar. Foram encontrados 15 artigos (que incluem 22 ensaios) presentes em sua maioria na região Centro-oeste do Brasil. A média e a mediana da capacidade de infiltração de todos os estudos foram 792 e 567 mm h-1, respectivamente. A maioria dos estudos (12 estudos) não define claramente qual o tipo de ecossistema foi avaliado. Além disso, a maioria dos estudos foram realizados em Latossolos. Em geral, os estudos tiveram um número amostral baixo para caracterizar as propriedades do solo. Diante disso, uma melhor descrição do tipo de ecossistema avaliado, bem como um número amostral mais significativo são necessários para compreender a infiltração de água nos ecossistemas naturais do Cerrado brasileiro. Em razão das limitações dos estudos encontrados, essa revisão mostrou que ainda é cedo para sintetizar e aprofundar a discussão deste tema em um bioma tão grande e heterogêneo.Palavras-chave: fitofisionomia, solo, vegetação nativa.

Seasonal Variations in Soil Microbiota Profile of Termite (Syntermes wheeleri) Mounds in the Brazilian Tropical Savanna.

Eusocial animals, such as the termites, often build a nest-like structure called a mound that provides shelter with stable internal conditions and protection against predators. Termites are important components of the Brazilian Cerrado biota. This study aimed to investigate the bacterial community composition and diversity of the Syntermes wheeleri termite-mound soil using culture-independent approaches. We considered the vertical profile by comparing two different mound depths (mound surface and 60 cm) and seasonality with samplings during the rainy and dry seasons. We compared the mound soil microbiota to the adjacent soil without the influence of the mound to test the hypothesis that the Cerrado soil bacterial community was more diverse and more susceptible to seasonality than the mound soil microbiota. The results support the hypothesis that the Cerrado soil bacterial community is more diverse than the mound soil and also has a higher variability among seasons. The number of observed OTUs (Operational Taxonomic Units) was used to express bacterial richness, and it indicates that soil moisture has an effect on the community distribution and richness of the Cerrado samples in comparison to mound samples, which remain stable across seasons. This could be a consequence of the protective role of the mound for the termite colony. The overall community taxonomic profile was similar between soil samples, especially when compared to the taxonomic composition of the Syntermes wheeleri termite’s gut, which might be explained by the different characteristics and functionality between the soil and the gut microbial community.

Understanding the effect of an agroforestry system with high litter input on topsoil permeability

AbstractSyntropic agroforestry systems (SYS) are a type of agroforestry in which very large amounts of organic matter (50–100 t ha−1 year−1) are added to the soil annually from pruning. However, information on the physical, chemical and biological effects of this management on soil is lacking. We characterized a SYS in terms of topsoil permeability (Mini‐Disk infiltrometer), soil organic matter (ignition method) and penetration resistance (Stolf penetrometer); we compared the results with those for a no‐till soy‐maize rotation and those within a native vegetation area (Brazilian Tropical Savanna), all on the same oxisol. The SYS had an infiltration capacity similar to that in the native vegetation area but which was higher than in the no‐till arable rotation. We relate this difference to both a lower penetration resistance and a high organic matter content in the SYS, possibly associated with higher litter input and with a greater above and belowground biomass. Our results indicate that SYS can be an efficient system for maintaining water infiltration at levels similar to those observed within natural ecosystems.

Techno-economic evaluation and mathematical modeling of supercritical CO2 extraction from Eugenia uniflora L. leaves

Extracts from Eugenia uniflora L. (pitanga) leaves grown in the Brazilian tropical savanna were obtained by supercritical CO2. The influence of temperature (40, 60 and 80 °C) and pressure (15, 20 and 25 MPa) on the extraction yield, overall extraction curves, kinetic parameters, chemical profiles, antioxidant activity, and total phenol content were evaluated. Amongst the conditions investigated, the highest global extraction yield (7.9 wt%) was found at 80 °C and 25 MPa, whereas the highest antioxidant activity (52.9 ± 0.9 %) and total phenol content (63.6 ± 4 mg GAE/g of leaves) were obtained at 40 °C and 25 MPa. Selina-1,3,7(11)-trien-8-one, oleic acid, phytol, and γ-sitosterol were the main compounds found in pitanga leaves extracts. The overall extraction curves showed that in most conditions, 67–92% of the extracted mass was recovered before the end of the constant rate extraction period. To estimate the cost of manufacturing (COM) of pitanga leaves extracts, the extraction process was simulated using the SuperPro Designer 8.5®. For extraction at 40 °C/25 MPa, the COM was US$ 654.90/kg, while for extraction at 80 °C/25 MPa, the COM was US$ 475.35/kg, both results for scale production of 100 L.

Microbiological indicators of soil quality are related to greater coffee yield in the Brazilian Cerrado region

Abstract One of the main challenges faced by the rapidly growing human population is to increase agricultural sustainability. Soil quality is an essential aspect of agricultural sustainability, but farmers have generally assessed this based on conventional chemical and physical indicators, with little application of indicators of soil functions, such as soil microbiological attributes. These indicators may respond faster to changes in soil conditions and thus they could correlate better with the growth/yield of crops such as coffee. The aim of this study was to investigate the potential of soil microbiological indicators in assessment of soil quality for sustained coffee production, compared to or combined with conventional soil physical and chemical indicators. To accomplish that, two observational studies were performed by measuring soil microbiological, physical, and chemical attributes in coffee field areas with contrasting records of coffee yield but under similar edaphic and climatic conditions in the Cerrado (Brazilian tropical savanna) region of Minas Gerais, Brazil. In the first study, two neighboring field areas with contrasting yield were selected for each of the following three cultivars: Catuai Vermelho IAC 99, Catuai Vermelho IAC 144, and Rubi MG 1192. Samples were taken in two seasons (dry and rainy) of the year. In the second study, four neighboring field areas cropped with the cultivar Catuai Vermelho IAC 144 were chosen based on their contrasting yield records. In both studies, the experimental procedure consisted of collecting four composite soil samples (each composed of four subsamples) taken at a depth of 0–10 cm from each field area within the area of canopy projection of the coffee plant. The microbiological attributes evaluated were microbial biomass carbon; microbial basal respiration; metabolic quotient; urease, β-glucosidase, and arylsulfatase enzyme activities; and fluorescein diacetate hydrolysis. The physical and chemical attributes evaluated were texture, pH, organic matter content, and fertility. Climatic conditions affected the responses and must be considered in evaluation and elaboration of soil quality indexes. The physical and chemical attributes that were most closely related to higher coffee yields were Ca contents, organic matter content, effective cation exchange capacity, and base saturation in both studies in the rainy season. Microbial biomass carbon, metabolic quotient, and β-glucosidase and urease activities were positively related to higher coffee yields, and these attributes exhibited greater ability to discriminate the production potential of the soil than chemical and physical attributes did, in both seasons and studies.