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There is still little information about Neossolos Regoliticos ( Neosols) , therefore, generating information about fertility, genesis and mineralogy is important to define the proper use and management. The work aimed to characterize morphologically, physically, chemically and mineralogically three Neossolos Regoliticos (Neosols) along a pluviometric gradient (400 mm; 400 and 600; 600 mm). For this purpose, trenches were opened, where the description and collection of soil samples proceeded. It was not possible to notice rainfall interference in the differentiation of horizons and depth of soils. However, increased clay contents from very dry soil to the sub-humid zone, showing the influence to rainfall that is also reflected in the natural fertility of Neossolos Regoliticos (Neosols)

Soil erosion is a serious world problem, especially in areas undergoing desertification. Rill and sheet erosions were estimated in one municipality of the largest desertification nucleus in the Brazilian semi-arid region. Measurements were made in plots located in combinations of the two main soil classes (Luvisol and Planosol, 58 and 40% of the municipal area) and the two predominant vegetation covers (sparse and open, 84 and 7% of the municipal area). The sparse vegetation has 320 plants ha−1 covering 25% of the soil surface and the open vegetation has 495 plants ha−1, covering 40% of the soil surface. Length, width, and depth of all rills were measured in the plots to calculate the soil losses. Sheet erosion was estimated assuming that the height of the soil close to the bases of trees and shrubs in relation to the soil surface away from these bases corresponded to the depth of the lost soil layer. Rill erosion was higher under the sparse vegetation than under the open vegetation: 400 versus 45 Mg ha−1. Sheet erosion did not differ among soils and covers (547–860 Mg ha−1). Soil loss in the municipality was 34 Tg and 24 Eg when extrapolating to the desertification nucleus. Erosion and low vegetation cover are cumulative reinforcing degradation drivers, leading to low crop and livestock productivity, poverty, and social vulnerability. Land use restriction is the main measure to reduce erosion, but it increases social problems.

The use of biochar as a soil amendment is being widely studied, whereas clay addition to meliorate soils has only been considered in a few studies. However, there is a limited understanding of the impact of biochar and clay on nutrient retention under field conditions, especially in seasonally dry tropical forests in semi-arid regions. In this study, biochar and clay were added to a tropical Arenosol to quantify nutrient leaching as a measure of nutrient retention to test the potential of both amendments for soil amelioration. In a field experiment, planting holes were prepared with 5 vol% medium-temperature biochar made of Prosopis juliflora (SW) DC, produced locally in the traditional manner in a kiln, or 10 vol% clayey sediment from a temporarily dry lake. Both amendments and control were tested as fertilised and unfertilised treatments. Then seedlings of the endemic tree Spondias tuberosa Arr. were planted. Self-integrating accumulators (SIAs) were used to quantify nutrient leaching at a depth of 0.7 m for ammonium-N (NH4+ − N), nitrate-N (NO3− − N), and potassium (K+). Leaching was assessed for two consecutive periods of eight months each. In the fertilised treatments, biochar addition significantly reduced NO3− − N leaching by 46% in the first period; leaching of all other nutrients was reduced but remained non-significant. In contrast, clay addition significantly reduced NH4+ − N leaching by 79% in the second period, K+ leaching by 51% in the first period, and by 45% in the second period, but significantly increased NO3− − N leaching by 57% in the second period. Both treatments showed pronouncedly different leaching patterns over time. Between the first and second period, the ability of biochar to reduce leaching relative to the control decreased by about half for the nutrients tested, whereas the ability of the clay treatment remained rather stable over 1.5 years for NH4+ − N and K+. The reason for the distinct decrease in nutrient retention of biochar in the second period may be the rapid decomposition of biochar carbon by 51% within 16 months. Under the given conditions, only clay can be recommended as a sustainable land management strategy to enhance NH4+ − N and K+ retention capacity of Arenosols in seasonally dry tropical forests.

Soil parental material is one of the main factors that influence pedogenesis. Several studies evaluated the relationship between the parent material and soil chemistry, but few studies have assessed such a relationship in semi-arid tropical regions. This investigation was carried out to assess the effect of different parent materials on the chemical composition and available concentrations of macronutrients and micronutrients, including potentially toxic elements (Cd, Cr, Ni, and Pb) in soils in a semi-arid tropical setting. The chemical composition of the soils inherited the geochemical signature of their parent materials. Quartz sandstones, augen gneisses, and peraluminous granites exhibited the lowest reservoirs of plant nutrients and formed sandy, acid, and infertile soils. On the other hand, alkaline soils and soils with high concentrations of nutrients formed on ultramafic rocks (harzburgite), marble, and anorthosite. The pH, clay content, and CEC were the main attributes of the soils governing the availability of macro and micronutrients. The low soil organic carbon contents did not influence the availability of the nutrients. The parent material also influenced the soil texture. Parent materials that are richer in silica formed more sandy soils. The availability of Cd, Cr, and Pb in soils was low; however, the elevated Ni concentrations of soils derived from ultramafic rocks may pose risks to the environment and human health. Cluster and discriminant analyses were used to discriminate the natural fertility of soils. These results are useful for the agro-pedological zoning of the Brazilian semi-arid tropical region and for land use planning.

Long-term irrigation in semi-arid regions leads to shifts in the soil moisture regime, affecting soil attributes and pedogenesis. Drylands are expected to increase worldwide, possibly because of climate change. Few studies have investigated changes in the pedogenic processes due to extensive irrigation in the Brazilian semi-arid region. This study assesses the effects of land use changes (irrigation and cultivation) on the morphological, physical, chemical, and mineralogical properties of soils. We evaluated two soil profiles in the semi-arid region in northeastern Brazil. We investigated an irrigated profile (IP) with long-term irrigation (26 years) and cultivation, and another profile under natural conditions (rain-fed hyperxerophilic Caatinga), that is, a non-irrigated profile (N-IP). The results indicate that land use affected chemical and mineralogical attributes of soils as well as the pedogenetic processes. Both soil profiles showed different behaviors in relation to salts: (1) reduction in soil exchangeable Na content (solodization) in IP, and (2) accumulation of soluble salts (salinization) and increased soil exchangeable Na content (solonization) in N-IP. Land use, possibly irrigation, induced mineralogical alteration pathways, such as the progressive mineral transformations via R0 MLM (mixed-layered minerals), suggesting differences in weathering and mineral evolution. The K-I (kaolinite-illite) and I-V (illite-vermiculite) phases predominated in the clay fraction in both soils and exhibited a greater trend for progressive kaolinization in IP. The other two MLMs (kaolinite-vermiculite, K-V and illite-smectite, I-S) were detected in N-IP and could be a proxy for the lowest weathering degree. This is consistent with the trend for a slight reduction in the SiO2/Al2O3 molecular ratio in IP. Illite was possibly the precursor mineral for other phyllosilicates, such as kaolinite, in IP. Fe-enriched MLM was detected in the decreasing sequence: illite, smectite, and kaolinite layers. The pedogenic trends observed, such as mineral weathering, may be attributed to system response to climate change.

The use of biogas as an alternative to using liquefied petroleum gas (LPG) for cooking food in the context of family farming is something recent and has ample room for growth. The aim of this study was to evaluate the use of the Sertanejo biodigester by farming families as a social technology for cooking gas production, as well as an alternative energy source. It also aimed to identify elements which contribute to disseminating this technology as an alternative to the use of firewood, charcoal and LPG. Quali-quantitative approaches were used following the exploratory method, with interviews and non-probabilistic sampling. A population with 132 units of biodigesters in the Agreste mesoregion of the State of Pernambuco was considered, with 83 interviews being collected. The results indicated that the Sertanejo biodigester social technology provides an increase in the income of farming families, avoids the use of firewood and charcoal for cooking food and produces biofertilizer for crops. They also showed that its non-continuous use or deactivation is related to a lack of raw material and the need for maintenance. Given this scenario, its implementation must consider the availability of a raw material source in the production unit and the potential for biogas production from the existing herd and consumption demand. It is recommended to strengthen arguments of economic and environmental impact for low-income families to disseminate this technology; to encourage the use of biogas associated with other activities in the production system; and to incorporate biodigestor social technology in rural credit financing lines. Made available in DSpace on 2022-02-12T02:09:33Z (GMT). No. of bitstreams: 1 Sertanejo-biodigestor-a-social-technology-2021.pdf: 1280147 bytes, checksum: 8c608e4ca15baa3ca73741ca67dee079 (MD5) Previous issue date: 2021

Soil management, although intended to create favorable structural conditions for crop growth and development, without prior assessment of potential and limitations, has been one of the reasons for the degradation of natural resources. The effects on soil degradation and respective structural quality are generally evaluated by some physical soil attributes such as bulk density (BD), total porosity (TP) and soil penetration resistance (PR). The PR is recognized as a physical parameter that supports the identification of areas with different stages of compaction and thus can be used to define appropriate management for soil remediation. Besides, this parameter depends on intrinsic soil factors (texture, structure, and mineralogy) and soil water content (SWC). Therefore, PR increases with BD and decreases with SWC (gravimetric or volumetric). Thus, it is possible to establish the critical limit of PR (PRCL) associated with the value of SWC that limits the growth of plant roots. PRCL varies according to soil type and plant species, but 2.0 MPa is the value scientifically accepted as the critical value to limit the root growth. Thus, the paper aimed to evaluate the spatial and temporal variability of PR in a field cultivated with sugarcane, under the conventional tillage system. The research was carried out in the Carpina Sugarcane Experimental Station, Pernambuco, Brazil. A grid of 70 x 70 m was delineated at intervals of 10 m and in each point soil samples were collected in the layers 0 - 0.30 m and 0.30 - 0.60 m depth. Three samplings were done to determine gravimetric soil water content; the first after six months of subsoiling (Time 6) before harrowing and planting, the second after 12 months of subsoiling (Time 12, six months after harrowing and planting) and the last after 18 months of subsoiling, before harvesting (Time 18). In each sampling time, in situ PR tests were carried out with the Solo Track equipment (Falker® - Model PLG 5300) and the simultaneous values of gravimetric soil water content were determined and associated with the PR data. The results showed that soil water content had a weak degree of spatial dependence, indicating the need to increase the number of samples. On the other hand, the PR values showed that the subsoiling did not promote a positive effect on the soil physical quality, with values above the PRCL for root development in Time 6 (2.42 MPa), even if after one year the sugarcane root system acted positively, by reducing PR in Time 18 (1.04 MPa) below the critical value.

Overexploitation of natural forest resources under the environmental conditions on the tropical semiarid region of Brazil is the main cause of soil degradation. This leads to insufficient restoration of both microbial and plant biomass and net loss of C and N from soils. In this study, we investigated degraded, partially degraded, and preserved Luvisols to quantify functional and total microorganisms and their activities and determine total C and N stocks. We hypothesize that degraded Luvisols have significant reduction in C and N stocks, abundance, and activity of total bacteria and fungi, diazotroph and phosphorus-mineralizing bacteria in relation to preserved or partially degraded Luvisols. We evaluated total C and N contents and stocks, microbial biomass (C, N and P), soil basal respiration, alkaline phosphatase activity, glomalin content, metabolic and microbial quotients and quantified 16S rRNA, 18S rRNA, nifH and phoD genes by real time quantitative PCR. C and N stocks of degraded Luvisols were a third of the stocks found in preserved soils. The values of soil microbial biomass and soil basal respiration on the degraded soils were ca. 1/5 and 1/20 in preserved soils; however, there was no indication of metabolic stress. The abundance of diazotrophic and phosphorus-mineralizing bacteria decreased in degraded Luvisols; nevertheless, total bacteria and fungi gene abundance as well as the glomalin content remained unchanged. The alkaline phosphatase activity indicated that mineralizing microorganisms could make phosphorus constantly available even in soils without vegetation cover.

In the Cabo Basin, NE Brazil, conglomerates have given rise to soils with attributes that are rarely observed in humid tropical climates and remain relatively unknown within the scientific community. These soils have high levels of Al in the exchangeable phase, diminishing their agricultural and environmental potential in an underdeveloped region of great socioeconomic importance. This paper presents the mineralogy and genesis of soils derived from conglomerates on a slope in the Cabo Basin, with the aim of meeting the demand for studies on Al–rich soils. Three soils were classified, morphologically described and sampled for the accomplishment of chemical, physical and mineralogical analyses, including the main exchangeable cations content, mineralogy of the sand, silt and clay fraction, differentiation of the Fe and Al forms, mineral micromorphology and chemical composition of mineral species. In addition, chemical and physical attributes were used in multivariate analyses. The soil mineralogy is associated with the weathering evolution of three mineralogical zones identified in the Cr horizons. Pathways of alteration followed by feldspars and micas resulted in kaolinite, smectite and hydroxy–Al interlayered smectite formation (argilification). The susceptibility of the conglomerate to weathering, constant releases of Al from the structure of aluminous minerals, low contents of exchangeable bases and consequent low pH values (

This research project sought a better understanding of how Northeastern Brazilian small operation horticultural farmers learn about their soils and how this is translated into land manageme...

Climate change in Brazil has led to an increase in temperature and changes in the distribution of climatic extremes, such as droughts and floods. This is potentialized when it comes to the brasilian semi-arid Northeast. Environmental studies related to this theme are in constant development. For this, the geotechnologies are of great importance for the environmental studies, since they allow the acquisition and analysis of information of use of the ground, vegetal cover and phenomena of the nature. In the present work, the Vegetation Cover Index was studied using remote sensing and geoprocessing techniques through the digital processing of images acquired in the years 2000 to 2015 of the LANDSAT satellites of three municipalities of Pernambuco to observe the vegetation cover in the said temporal space with the degraded areas possibly resulting from the desertification process in the region. Thus, it was found that the municipalities of Betânia and Itacuruba have very high vulnerability (0.75 and 1, respectively). On the other hand, the municipality of Floresta presented a high vulnerability of ICV (0.5), as the vegetation deficit influences hydrological dynamics, soil protection, climatic stability and thermal influence, corroborating the desertification process. Made available in DSpace on 2020-02-03T18:09:17Z (GMT). No. of bitstreams: 1 UseofVegetationCoverIndextoidentifysusceptibleareastodesertificationprocess2020.pdf: 629847 bytes, checksum: 6080cfdf17642427e9f770826cb7e453 (MD5) Previous issue date: 2020

World climate change has triggered soil water stress and imposed limitations on agricultural production. Plant growth-promoting bacteria (PGPBs) have been an efficient strategy to improve the biological supply and growth of plants under distinct abiotic stress conditions. We hypothesized that the soils from a temporary pond may harbor PGPBs with potential strains which increase maize tolerance to water deficit. We studied rhizosphere and bulk soil of Mimosa bimucronata in a temporary pond from semiarid Northeast Brazil to access strains with characteristics to promote plant growth and mitigate abiotic stress for maize crop. We isolated 355 bacterial isolates, from which 96 were selected based on the morphophysiological characterization to assess IAA production (42 % produced over 50 ug mL-1 of IAA), calcium phosphate solubilization (with one isolate achieving medium IS), biofilm and exopolysaccharides production (66 % and 98 % of isolates, respectively). Based on these mechanisms, the 30 most promising bacterial isolates were selected to assess biological nitrogen fixation (74 % of the isolates showed nitrogenase activity greater than 20 C2H4.h-1.mg-1), ACC deaminase activity (80 % of isolates) and growth in medium with reduced water activity (8 % of isolates grew in medium with water activity (Aw) of 0.844). We sequenced the 16S rRNA gene from the seven most promising isolates in in vitro and in vivo assays, which were identified as Staphylococcus edaphicus, Bacillus wiedmannii, Micrococcus yunnanensis, Streptomyces alboflavus, Streptomyces alboflavus, Bacillus wiedmanni and Bacillus cereus. In vivo, eleven isolates and three bacterial consortia did not differ from the control with nutrient solution, for total leaf area and root dry mass of maize. S. alboflavus (BS43) had the best in vivo results, not differing from the control with nutrient solution. We highlight the unpublished potential of Staphylococcus edaphicus and Streptomyces alboflavus in promoting the growth of plants under water stress. In addition, it is the first report of bacteria isolated from a temporary pond in the Brazilian semiarid which promoting plant growth attributes and development. Made available in DSpace on 2021-11-12T12:01:12Z (GMT). No. of bitstreams: 1 Bacteria-from-tropical-semiarid-temporary-ponds-2020.pdf: 1063882 bytes, checksum: d98a0b8af8d7063bd8ef46dc344c460a (MD5) Previous issue date: 2020

Planosols, such as those found on the Borborema Plateau, NE Brazil, form an important class of moderately weathered soils that support subsistence agriculture in underdeveloped regions of Africa, Asia, and South America. Despite its socioeconomic importance, the genesis of this soil class has not yet been fully elucidated. This study was conducted with the aim of improving knowledge about the genesis of Planosols under a semi-arid climate. Three Planosol profiles on the Borborema Plateau in NE Brazil were collected, classified, and described morphologically, and the main physical and chemical attributes, the pedogenetic forms of iron oxides, and the mineralogical compositions of the sand, silt, and clay fractions were determined. The results indicate that: (a) parent materials richer in feldspar and biotite favor the formation of Planosols with a higher clay content; (b) the dissolution of primary minerals and the formation of clay minerals (known as the argillation process) are fundamental for the genesis of Bt horizons; (c) depth-drainage deficiency leads to hydromorphism, an associated gray color, and the formation of mottles; and (d) monosialitization and bisialitization processes (kaolinite formation and the formation of 2:1 clay minerals, respectively) prevail in Planosols located within landscape positions that have good and poor drainage, respectively. In addition, the present study shows that Planosols under a semi-arid climate can have a clay fraction consisting predominantly of kaolinite, and mineralogical alteration pathways similar to those described in soils under an analogous climate and geology in Northwest Africa; this refutes classical theories that soils with 2:1 clay minerals prevail in warmer and drier regions. This study thus provides greater knowledge about the attributes of Planosols in dry and poor regions and can be used as a reference in studies on the sustainable use and management of such soils.

ATRIBUTOS FÍSICO-HÍDRICOS DO SOLO VIA FUNÇÕES DE PEDOTRANSFERÊNCIA EM SOLOS DOS TABULEIROS COSTEIROS DE PERNAMBUCO FERNANDA HELENA NASCIMENTO DE ANDRADE1; CERES DUARTE GUEDES CABRAL DE ALMEIDA2; BRIVALDO GOMES DE ALMEIDA3; JOSÉ AUDIFAX CÉZAR DE ALBUQUERQUE FILHO1; BRUNO CAMPOS MANTOVANELLI4 E JOSÉ COELHO DE ARAÚJO FILHO5 1 Departamento de Engenharia Agrícola, Programa de Pós-Graduação em Engenharia Agrícola da Universidade Federal Rural de Pernambuco - UFRPE, Rua Dom Manuel de Medeiros, S/N, Dois Irmãos, CEP: 52171-900, Recife, PE, Brasil, fernanda_andrade89@hotmail.com, jaudifax@deagri.ufrpe.br 2 Colégio Agrícola Dom Agostinho Ikas, Programa de Pós-Graduação em Engenharia Agrícola da Universidade Federal Rural de Pernambuco - UFRPE, Rua Dom Manuel de Medeiros, S/N, Dois Irmãos, CEP: 52171-900, Recife, PE, Brasil, ceres.codai.ufrpe@gmail.com. 3 Departamento de Agronomia, Programa de Pós-Graduação em Ciência do Solo da Universidade Federal Rural de Pernambuco - UFRPE, Rua Dom Manuel de Medeiros, S/N, Dois Irmãos, CEP: 52171-900, Recife, PE, Brasil, brivaldoalmeida@gmail.com. 4 Departamento de Ciências Rurais, Programa de Pós-Graduação em Ciência do Solo da Universidade Federal de Santa Maria - UFSM, Avenida Roraima, n° 1000, Camobi, CEP: 97105-900, Santa Maria, RS, Brasil, brunomantovanelli21@gmail.com. 5 Empresa Brasileira de Pesquisa Agropecuária, EMBRAPA Solos - UEP Recife, Rua Antônio Falcão, n° 402, Boa Viagem, CEP: 51020-240, Recife, PE, Brasil, jose.coelho@embrapa.br. 1 RESUMO Objetivou-se gerar funções de pedotransferência (FPT) com base em dados das frações granulométricas, distribuição do tamanho de poros, densidade do solo e de partículas para estimar a umidade do solo equivalente à capacidade de campo (CC), ponto de murcha permanente (PMP) e a capacidade de armazenamento de água disponível (CAD) em Argissolos Amarelos representativos dos tabuleiros costeiros na zona da mata norte de Pernambuco. Para isso, foram coletadas amostras deformadas e indeformadas na camada 0,00 - 0,20 m de profundidade. As FPTs foram geradas a partir do método de regressão linear múltipla aplicando a técnica de stepwise backward. Este método eliminou alguns atributos físico-hídricos do solo baseado nos valores de R2 e no Teste t. Os coeficientes de regressão do modelo proposto para predição de CAD, CC e o PMP apresentaram significância de 1% de probabilidade para as variáveis independentes selecionadas para cada modelo, indicando que esses parâmetros podem ser preditos, com ótima precisão, a partir do conteúdo de areia, argila, mesoporosidade, microporosidade e densidade do solo, as quais são fáceis de serem determinadas e obtidas, pré-requisito básico para construção das FPTs. Palavras-chave: manejo de irrigação, stepwise backward, índices estatísticos. ANDRADE, F. H. N.; ALMEIDA, C. D. G. C.; ALMEIDA, B. G.; ALBUQUERQUE FILHO, J. A. C.; MANTOVANELLI, B. C.; ARAÚJO FILHO, J. C. SOIL PHYSICAL-HYDRIC PROPERTIES BY PEDOTRANSFER FUNCTION IN SOILS OF COASTAL PLAINS OF PERNAMBUCO 2 ABSTRACT Aimed to generate pedotransfer functions (PTF) based on particle size, pore size distribution, soil and particle density to estimate the field capacity (CC), permanent wilting point (PMP) and available water capacity (CAD) in Ultisol Typic Fragiaquults in coastal plains of Pernambuco. Thus, deformed and undeformed samples were collected at 0.00 - 0.20m depth. PTFs were generated from multiple linear regression method by stepwise backward technique. This method eliminated some hydro-physical soil attributes, based on the values of R2 and t test. CAD, CC and PMP estimated values showed a significant correlation of 1% probability for independent variables selected for each model. Thus, available water capacity, field capacity and permanent wilting point can be predicted with great precision by sand, clay content, mesoporosity, microporosity and soil density, which are easy to determine and obtain, basic prerequisite for construction of PTFs. Keywords: irrigation management, stepwise backward, statistical indexes.

RESUMO O conhecimento da analise quantitativa das concentracoes de sedimentos em suspensao transportados pelo rio Sao Francisco bem como sua relacao com as vazoes e de muita importância, pois pode auxiliar na identificacao dos efeitos da intervencao humana e ou ocasionados pelas condicoes naturais da regiao. As regioes a jusante dos barramentos no rio Sao Francisco apresentam como principal consequencia a regularizacao das vazoes e a diminuicao das concentracoes de sedimentos. O objetivo da pesquisa foi determinar as curvas-chave de sedimentos em suspensao (CCS) nas estacoes fluviometricas instaladas no Baixo Sao Francisco (BSF) apos a barragem de Xingo. Para o estabelecimento dessas curvas foram utilizados dados de vazao e concentracao de sedimentos em suspensao, obtidos do sistema Hidroweb no site da Agencia Nacional da Agua (ANA) no periodo de 1999 a 2018. Foram obtidas CCS para todo o trecho do BSF as quais apresentaram bons coeficientes de determinacao. Na analise dos dados tambem foi possivel perceber que nos ultimos anos, desde 2013 houve reducao gradativa das vazoes disponibilizadas na barragem de Xingo. Consequentemente, houve tambem a reducao gradativa das cargas de sedimentos em suspensao geradas nas estacoes de Piranhas, Traipu e Propria, ou seja, os menores valores ja registrados no BSF correspondendo as menores series historicas tanto de vazao como de sedimentos em suspensao. Keys curves of sediment discharges in suspension in the Lower Sao Francisco A B S T R A C T The knowledge of the quantitative analysis of suspended sediment concentrations carried by the Sao Francisco River as well as its relation with the flows is of great importance, since it can help in the identification of the effects of human intervention and/or caused by the natural conditions of the region. In the downstream regions of the Sao Francisco riverbanks, the main consequence was the regularization of flow rates and the reduction of sediment concentrations. The objective of the research was to determine the key curves of suspended sediments (CCS) at the fluviometric stations installed in the lower Sao Francisco river after Xingo dam. For the evaluation, flow data and suspended sediment concentration were used. These data were obtained from the Hidroweb system on the website of the National Water Agency (ANA) from 1999 to 2018. CCS were plotted for all stretches and presented good coefficients of determination (R 2 ). Based on the analysis of the data it was also possible to notice that in recent years, since 2013 there has been a gradual reduction of the flows available in the Xingo dam. Consequently, there was also a gradual reduction of suspended sediment loads generated at the Piranhas, Traipu and Propria stations, that is, the lowest values already recorded in lower Sao Francisco, corresponding to the lower historical series of both discharge and suspended sediments. Keywords: dam, flow, sediments

Knowing particularities of soils allows the adoption of sustainable management practices. The most efficient method to obtain data on the soil is through its characterization, essential for planning land use and soil conservation. However, soil surveys conducted in the conventional methods are costly and time-consuming. This study aimed to identify spectral patterns in the mid-IR wavelengths for a quick and low cost characterization of soil classes. Soils from the Natuba river basin, Pernambuco State, Brazil, were used. These soils were mapped on a scale of 1:25,000, where the presence of Latossolos, Argissolos, Gleissolos and Neossolos were identified. The data of reflectance for profiles of each soil class were collected using the spectral range between 2,500 and 25,000 nm. In the mid-IR region, Latossolos and Argissolos presented spectral characteristics peculiar to classification criteria. The increased contents of organic matter and iron oxides reduced soil reflectance. The horizons with sand content above 80% showed strong absorption spectra and significant reflectance peaks of quartz in the mid-IR. The wavelengths 2,681, 2,600 and 2,495 cm-1 occurred only in these horizons. The spectral analysis presented as a high-potential method for the characterization and classification of soils. Made available in DSpace on 2021-11-11T18:01:23Z (GMT). No. of bitstreams: 1 Spectral-patterns-in-the-mid-ir-of-soils-2020.pdf: 1946587 bytes, checksum: accd3d9898b084c2f681d811735bd48b (MD5) Previous issue date: 2020

Clay skins are morphological features that manifest in soils as a waxy shine, mainly on the surface of aggregates. Their genesis is related to the formation of pellicles or films of clay and micro features of stress on ped faces. Clay skins provide pedogenetic evidence and may indicate previous or current occurrence of flocculation and dispersion, as well as the nature of constituent minerals of the soil. Thus, we aimed to study the genesis of clay skins, testing the hypothesis that they are formed as a result of alternating micro-swelling and shrinking processes and that the argilluviation is currently inexpressive. For this, a toposequence of eutric soils from metamorphic rocks (gneiss-migmatite) in a tropical forest environment was studied. Soil sampling based on a structural model of the pedological coverage, as well as physical and chemical analyses; monitoring of clay dispersion in water; coefficient of linear expansivity; x-ray diffractometry; selective dissolution of Fe oxides using sodium citrate-bicarbonate-dithionite and acid ammonium oxalate; optical and electron microscopy analyses; and modelling of x-ray diffractometry patterns using ClaySIM software were carried out. The results indicated that clay dispersion in the studied eutric soils seems to be of little significance during the rainy period since the greater dissociation of bivalent cations such as Ca2+ and Mg2+ favors the forces of attraction forming cationic bridges, resulting in the union between negatively charged particles. Furthermore, the illite-vermiculite phase may have little influence on the macro-morphological properties of the soils; although on a microscopic scale, it may favor the formation of granostriated b-fabrics. Clay skin formation in soils of a hot, humid tropical climate is essentially controlled by the argilluviation process and by wetting and drying cycles, the expression of this feature being proportional to the quantity of intra-aggregate voids (smaller size voids). Nevertheless, the orientation and metallization process (hematization) of the coatings and infillings seem to determine the expressiveness of the clay skins, and the type of b-fabrics and their development variations are not related, or are insignificant, in regard to the occurrence and degree of development of clay skins.

The lack of robust scientific data still hinders estimates of soil and plant carbon (C) losses due to land-use changes in most dry tropical ecosystems. The present study investigated the effects of land-use and cover changes on total ecosystem C stocks in NE Brazil, aiming to quantify C losses after the removal of the native forest, known as Caatinga. The sampling design included the four main land-use/cover types (Dense Caatinga, Open Caatinga, Pastures and Crop fields) and the seven main soil classes (Arenosols, Acrisols, Regosols, Ferrasols, Luvisols, Planosols, and Leptosols), a combination that represents over 90% of the region. This design resulted in 192 sampling points (48 in each land-use), distributed proportionally to the area of occurrence of each soil class. In each sampling point, we determined C stocks in soil organic matter (SOM) and roots (to a depth of 1 m or rock layer), aboveground vegetation biomass (trees and herbs, separately), deadwood, and surface litter. Areas covered by Dense Caatinga store, on average, nearly 125 Mg ha−1 of C. Most of this C is stored in the soil organic matter (72.1%), followed by aboveground biomass (15.9%), belowground biomass (7.3%), deadwood (2.9%), litter (1.3%), and herbaceous biomass (0.5%). The substitution of Dense Caatinga to plant pastures and crop fields caused losses of >50% of ecosystem C stocks, reaching almost 65 Mg ha−1 of C, with nearly equal losses from the SOM and vegetation biomass compartments. Open Caatinga store nearly 30% less C than Dense Caatinga. Contrary to what was expected, the overall differences in C stocks between soil classes were not significant, with a few exceptions. We expect that the findings of this study will contribute to a more robust inventory of GHG emissions/removals due to land-use changes in NE Brazil and other dry tropical regions of the globe.

The expansion of the agricultural frontier in search of new productive regions around the world has raised the attention of the scientific community to the genesis and agricultural potential of soils in regions of the planet where the dry climate limits agricultural activities. In this context, our goal was to describe if there is a direct relationship between the weathering of different metamorphic rocks and the genesis of Luvisols and Planosols in a semiarid region of Brazil, describing the implications of the genesis of these soils for their agricultural potential. For this, two Planosols profiles and three Luvisols profiles were classified, described morphologically and sampled for the development of physical, chemical, mineralogical and micromorphological analyzes. Samples of the respective parent rocks were collected for petrographic analysis and physical and chemical attributes were used in multivariate statistical analysis. The results indicate that: a) weathering of gneiss and amphibolite results in genesis of Planosols and Luvisols respectively, b) hematite was more associated with Luvisols and goethite was more associated with Planossols, and this variation in the content of iron oxides influenced some morphological attributes of these soils, c) clay formation in situ called argillation was the main process responsible for the genesis of Bt horizons in both soils, d) alterations of plagioclases, biotite and amphibole influenced the release of plant nutrients such as Ca+2, Mg+2 and K+ and e) the set of attributes analyzed led us to affirm that Luvisols have a more relevant agricultural potential than Planosols in the semiarid region studied. Our conclusions can be extrapolated to other regions of the world under similar geoclimatic conditions.

Os Tabuleiros Costeiros possuem camadas coesas de solos que alteram o estado da água nos seus poros, interferindo no desenvolvimento do sistema radicular das plantas. Este estudo objetivou avaliar a ação dos condicionadores poliacrilamida (PAM) e gesso no solo coeso de Tabuleiros Costeiros de Pernambuco via intervalo hídrico ótimo (IHO). As amostras foram subdivididas em três tratamentos — T0 (Controle), T1 (PAM) e T2 (PAM + gesso) —, com quatro repetições cada. Foram avaliadas a curva característica de retenção de água no solo; a densidade do solo; a resistência do solo à penetração de raízes (RP) e o IHO. As médias foram submetidas à ANOVA e ao teste de Tukey, pelo aplicativo Statistical Analysis System (SAS). O IHO foi eficiente em detectar alterações na disponibilidade de água do solo; o tratamento com PAM foi o que promoveu maior aumento dessa disponibilidade, e o valor crítico da RP para o IHO do solo coeso estudado ficou acima de 2 MPa.

In order to develop a method for extensive pomiculture on marginal soils in semiarid Brazil, a field experiment was conducted to study the impacts of the soil conditioners biochar, clay substrate and goat manure on soil physical parameters of a sandy soil and on seedling performance of Spondias tuberosa Arruda. Manure significantly increased total porosity, soil water content and reduced bulk density of the sandy soil. Water content at field capacity (θfc) and at permanent wilting point (θpwp) were increased due to manure application. Neither biochar nor clay substrate had a significant impact on the soil physical parameters. Biochar combined with clay substrate led to lower soil water content and significantly reduced the period of retaining atmospheric water. Due to a strong correlation (R2 = 0.75) between θfc and θpwp, the available water capacity within all treatments remained unchanged. Amelioration and initial nutrient supplies had no effect on seedling survival and stem growth of S. tuberos...

Light soils occupy 8% of the Brazilian territory and are especially expressive in the new and last agricultural frontier in Brazil: the Matopiba region - in the states of Maranhão, Tocantins, Piauí, and Bahia -, where they represent 20% of the area. These soils fit into the textural classes of sand and loamy sand or sandy loam, down to 0.75-m soil depth or deeper, and they are mainly represented by Neossolos Quartzarênicos (Quartzipsamments) and, partly, by Latossolos (Oxisols) and Argissolos (Ultisols). The understanding of soil functioning depends on the establishment of distinguishing criteria for: organic matter dynamics; content and mineralogy of the clay fraction; coarse sand and total sand contents, in relation to those of fine sand; mean diameter of the sand fraction; and water retention capacity. These criteria can contribute for the zoning and for the conservation and fertility management of light soils, as well as for the estimation of their agricultural potential. Integrated production systems, such as crop-livestock and crop-livestock-forestry integration, besides no-tillage with crop rotation, mixed forestry planting with legumes, and the use of green manure and cover crops are relevant for the proper management of these soils. The objective of this review was to characterize light soils and to highlight the main challenges regarding their agricultural potential and their conservation and fertility managements, in face of the expansion and consolidation of the new Brazilian agricultural frontier. Resumo Os solos leves ocupam cerca de 8% do território brasileiro e são epecialmente expressivos na nova e na última fronteira agrícola do país: a região de Matopiba, nos estados do Maranhão, do Tocantins, do Piauí e da Bahia, onde representam 20% da área. Esses solos enquadram-se nas classes texturais areia e areia franca ou francoarenosa, até a profundidade de 0,75 m ou mais, e são representados principalmente pelos Neossolos Quartzarênicos e, em parte, por Latossolos e Argissolos. O entendimento do funcionamento desses solos depende do estabelecimento de critérios distintivos sobre: dinâmica da matéria orgânica; teor e mineralogia da fração argila; teores de areia grossa e de areia total, em relação aos de areia fina; diâmetro médio da fração areia; e capacidade de retenção de água. Esses critérios podem contribuir para o zoneamento e para o manejo conservacionista e da fertilidade dos solos leves, bem como para estimação de seu potencial agrícola. Sistemas integrados de produção, como os de integração lavoura-pecuária e lavoura-pecuária-floresta, além do plantio direto com rotação de culturas, dos plantios florestais mistos com espécies leguminosas, e do uso de adubos verdes e cultivos de cobertura, são relevantes para o manejo adequado desses solos. O objetivo deste artigo de revisão foi caracterizar os solos leves e apontar os principais desafios em relação a seu potencial agrícola, a seu manejo e conservação e sua fertilidade, frente à expansão e à consolidação da nova fronteira agrícola.

O semiárido brasileiro é uma região onde os fatores edafo-climáticos requerem políticas públicas contextualizadas ao local para que haja uma convivência harmônica com o semiárido. As cisternas de placas utilizadas na região são instrumentos capazes de promover a captação de água das chuvas para dessedentação humana, animal, produção de alimentos e diversos usos, aproveitando o potencial hídrico da região, utilizando o indivíduo beneficiário como ator principal na implementação do equipamento, sendo considerada uma tecnologia social, favorecendo dessa forma a economia local e promovendo o desenvolvimento sustentável. O presente artigo apresenta as variedades de cisternas utilizadas no semiárido e avalia o potencial hídrico de cada uma, evidenciando que as cisternas de placa são tecnologias sociais relevantes para a convivência com o semiárido, proporcionando água de qualidade para os diversos usos a que é destinada e promovendo o desenvolvimento local. ABSTRACT The Brazilian Semiarid region is a region where the soil and climatic factors require public policies at local contextualized so that a harmonious coexistence with the nature. The cisterns used in the region are instruments to promote the uptake of rainwater for watering human, animal, food production and various uses. This tecnology taking advantage of the water potential of the region, using the individual beneficiary as the main actor in the implementation of the equipment, being considered a social technology, thereby favoring the local economy and promoting sustainable development. This article presents the varieties of tanks used in Semiarid and evaluates the water potential of each. The results showing that the plate tanks are relevant social technologies for coexistence with the Semiarid region, providing quality water for the various uses to which it is intended and promoting local development. Keywords: Water Resources, Social Technology, Living with the Semi-Arid.

Improper management and exploitation of the natural resources of the semiarid Planosols have triggered irreparable degradation processes in which vegetation can no longer reestablish itself naturally. We investigated preserved and degraded Planosols from Pernambuco State, Brazil, to determine total C and N stocks and quantify the functional and total microorganisms. We hypothesized that the degraded Planosol would have: i-significant reductions in C and N stocks, microbial biomass and activity in relation to the soil with preserved vegetation; ii-significant decreases in the proportion of total diazotrophic bacteria and archaea, ammonia-oxidizing bacteria, iron-reducing and -oxidizing bacteria and in alkaline phosphatase producers along the pedogenetic horizons. Thus, microbial biomass, soil basal respiration and metabolic and microbial quotients were obtained. Furthermore, total and functional gene copies were quantified by quantitative polymerase chain reaction (qPCR), and the functionality of biological nitrogen fixation (BNF) was determined using an acetylene reduction assay. In degraded Planosols, the activity from the present diazotrophs has been responsible for maintaining soil N stocks (i.e. soil N stocks without significant differences between the evaluated Planosols), but the soil C stocks were halved. Biomass and microbial activity did not show significant differences between two Planosols and there was no apparent metabolic stress from the identified microbiota. We found a significant proportion of structural and functional microorganisms in both Planosols. There were many archaea predominating in the Bt pedogenetic horizon in both Planosols, and a high proportion of microorganismal alkaline phosphatase was also found. We highlight the need for studies on BNF efficiency, especially focusing on archaea and free-living bacteria, as they are performing this important biological function, even in totally degraded semiarid soils.

The properties of halomorphic soils are controlled by the presence of either soluble salts, exchangeable sodium or both, and it is important to know and understand these properties in order to reforest and/or recover the soils. The objective of this study was to characterize and classify halomorphic soils from the semiarid region of Northeast Brazil. Four profiles of halomorphic soils were studied, which were described morphologically and the samples were collected from all soil horizons. Physical and chemical analyzes of the soils were carried out for classification purposes, as well as geochemical speciation of the soluble salts. According to the results, P1 and P3 were classified as Fluvisols, and P2 and P4 as Cambisols. It was observed that the studied soil profiles have the predominance of fine particles, which prevents the leaching and subsequent removal of salts from the soil profile. Soils presented high levels of exchangeable sodium, characterizing them as sodium solids throughout the profile. Ionic speciation analysis indicated the predominance of free forms of Ca2+, Mg2+, Na+ and K+, HCO3-, Cl- and SO42- and combinations of calcium, magnesium and sodium chloride and sulfate salts. Thus, it was possible to conclude that the studied halomorphic soils presented high levels of degradation by salts and sodium and that these types of soils are strongly related to the Fluvisols and Cambisols. Made available in DSpace on 2019-07-09T00:45:24Z (GMT). No. of bitstreams: 1 2019026.pdf: 325550 bytes, checksum: 47a6e1bf4c983685ecc02f08c10ba705 (MD5) Previous issue date: 2019