Interação dos atributos químicos do solo em área com floresta natural e com plantio de laranja (Citrus sinensis L Osb.)

Na região amazônica é comum a conversão de ambiente natural para o de cultivo, com isso o solo permanece em constantes modificações. As atividades agrícolas podem incrementar a heterogeneidade do solo provocando alterações nos atributos químicos do solo, decorrente principalmente das atividades de manejo e cultivo. Essas mudanças são mensuráveis e contribuem para caracterizar, avaliar e acompanhar as alterações ocorrida utilizando ferramentas estatísticas. Assim o estudo da variabilidade espacial dos atributos químicos dos solos é particularmente importante especialmente em áreas onde o solo está submetido a diferentes manejos, visando reduzir os efeitos da variabilidade na produção das culturas em função de determinadas práticas de manejo. Dessa forma, este trabalho tem por objetivo avaliar a variabilidade espacial dos atributos químicos em área de floresta natural e com cultivo de laranja em Colorado do Oeste, Rondônia. Foram selecionadas duas áreas de estudo, a primeira sendo a área de floresta nativa e a segunda sob cultivo de laranja em de Colorado do Oeste, Rondônia. Em cada área foi delimitada uma malha com 1.260 m² (42 x 30 m), com 48 pontos e espaçamento regular entre pontos de 6 m. Nos pontos de cruzamento da malha foram coletadas amostras em três profundidades (0,00-0,05; 0,05-0,10 e 0,10-0,20 m), correspondente ao horizonte diagnóstico do solo, perfazendo uma somatória de 144 amostras por área, logo, um total de 288. Serão determinados dos atributos químicos de pH em água, acidez potencial, alumínio trocável, fósforo e potássio disponível, e carbono orgânico. Com a obtenção dos dados, estes foram avaliados por meio de estatística descrita com teste de médias e a realização da análise multivariada. Houve diferença entre as duas áreas, a substituição da vegetação nativa por sistema de cultivo, ocasionou alterações nos atributos químicos do solo. O uso das técnicas multivariadas mostrou-se eficiente na distinção dos ambientes estudados. Interaction of the chemical attributes of the soil in an area with natural forest and with planting of orange (Citrus sinensis L. Osb.) A B S T R A C TIn the Amazon region it is common to convert from a natural environment to that of cultivation, with this the soil remains in constant modifications. Agricultural activities can increase the heterogeneity of the soil causing changes in the chemical attributes of the soil, mainly due to management and cultivation activities. These changes are measurable and contribute to characterize, evaluate and monitor the changes that have occurred using statistical tools. Thus, the study of the spatial variability of the chemical attributes of soils is particularly important, especially in areas where the soil is subjected to different managements, in order to reduce the effects of variability in the production of crops due to certain management practices. Thus, this work aims to evaluate the spatial variability of chemical attributes in an area of natural forest and with orange cultivation in Colorado do Oeste, Rondônia. Two study areas were selected, the first being the native forest area and the second under orange cultivation in Colorado do Oeste, Rondônia. In each area, a mesh of 1,260 m² (42 x 30 m) was delimited, with 48 points and regular spacing between points of 6 m. At the crossing points of the grid, samples were collected at three depths (0.00-0.05; 0.05-0.10 and 0.10-0.20 m), corresponding to the soil diagnostic horizon, making a sum of 144 samples per area, therefore, a total of 288. The chemical attributes of pH in water, potential acidity, exchangeable aluminum, available phosphorus and potassium, and organic carbon will be determined. Once the data were obtained, they were evaluated using statistics described with the means test and the multivariate analysis. There was a difference between the two areas, the replacement of native vegetation by a cultivation system, caused changes in the chemical attributes of the soil. The use of multivariate techniques proved to be efficient in distinguishing the studied environments.Keywords: Amazon soils, Use and management, Soil occupation.

Time for non-illuvial Bt horizons?

The Bt horizon is the diagnostic horizon of the Luvisolic Order in Canada. According to the Canadian System of Soil Classification (CSSC), the Bt must be formed from clay illuviation through the processes of lessivage (i.e., physical transport of clay). In a study of a Luvisol catena in the central Saskatchewan, we demonstrate that Ae/Bm horizons overlying IIBt horizons are formed in a sandy mantle overlying till (i.e., a lithological discontinuity) and that the sandy mantle contributed negligible amounts of illuvial clay despite the presence of clay skins on ped surfaces in the IIBt horizon. We extended the results of this study to the regional scale by examining sand fractions in 63 pedons of Luvisol-dominated soil associations from soil surveys in the Northern Forest Reserves (between latitudes 53^oN and 55^oN). Of the 63 pedons, 13 had lithological discontinuities identified in their profile description and a further 27 had discontinuities identified through shifts in the sand fractions between horizons. For the profiles with discontinuities, inherited particle size differences are a more likely cause of coarse-over-fine textural contrasts than lessivage. A regional analysis of the distribution of Luvisol-dominated associations showed distinct zonations that account, in part, for the differences in the occurrence of lithological discontinuities. Based on these results, we suggest that the criteria for Bt horizons in the CSSC should be broadened to include non-illuvial coarse-over-fine texture-contrast horizons and that the criteria for the Luvisolic order also be broadened to include these non-illuvial Bt horizons.

Potentialities and limitations of Planosols with distinct depths of diagnostic horizon

There is a variation in the depth of subsurface horizon of Planosols in semi-arid region, which may influence the agricultural potential and affect food production. The general aim of this study was to identify potentialities and limitations of two Planosols as a function of subsurface horizon depth. The adjacent profiles P1 and P2 were studied in Pentecoste (Ceará, Brazil). Morphological, physical, and chemical analyses were done aiming at soil characterization. Soil bulk density (BD), porosity, and penetration resistance (PR) were analyzed in a completely randomized split-plot design with four replicates to compare P1 and P2 and the horizons Ap and Btf. Btf was found at 62cm depth in P1 and at 18 cm depth in P2. Indicatives of water saturation were more evident in P2. The profile P1 showed lower hardness and higher friability, as well as higher acidity in subsurface (pHH2O from 4.4 to 4.7) and higher aluminum content (1.2cmolc kg-1). Both profiles were eutrophic and showed low contents of organic carbon (1.5 to 8.5g kg-1) and phosphorus (0.9 to 3.9mg kg-1). The sodium percentage in CEC was 9.1% in P1 and 5.5% in P2. Water retention increases in Btf compared with Ap was 7.3% in P2 and 2.7% in P1. Both profiles showed increase in BD in Btf, reaching 1.7g cm-3, while PR was higher in P2 (1.5 MPa). There are potentialities and limitations common to both soil profiles, but P1 has more physical potentialities and more chemical limitations than P2.

Soils of Thotapalli Major Irrigation Project of North-Coastal Andhra Pradesh: Characterization and Classification

Six representative pedons from Devarapalli (P1), Gujjangivalasa (P2), Patikivalasa (P3), Gangada (P4), Aamiti (P5) and Maddivalasa (P6) villages belonging to ayacut of Thotapalli major irrigation project of North-Coastal Andhra Pradesh were studied. Pedons 1, 2 and 5 were developed from granite-gneiss, while pedons 3, 4 and 6 had their parent legacy with granite-gneiss mixed with calcareous murrum. The soils of P1 and P2 were moderately deep to very deep having argillic horizon while cambic sub-surface diagnostic horizon was noticed in P3, P4 and P5. Deep and wide surface cracks and slickensides close enough to intersect were observed in P4 and P6. The pedons P1, P2, P3 and P5 had sandy loam to sandy clay loam texure and it was clay loam to clay in cultivated plains (P4 and P6). The soils were low to medium in organic carbon content. The CEC ranged from 6.4 to 32.5 cmol (p+) kg-1 and the soil exchange complex was dominated by calcium followed by magnesium, sodium and potassium. The ratio of CEC/ clay was low in P2, medium in P1, P3 and P5 and high in P4. Devararapalli pedon was classified as Typic Haplustalfs, Gujjangivalasa as Typic Haplustults, Patikivalasa and Amiti as Typic Haplustepts, Gangada as Vertic Haplustepts and Maddivalas as Chromic Haplusterts.

Research on the Presence Greyic Phaeozems in Romania

Areas under greyic phaeozems of Romania corresponding geographical areas as compared lithostratigraphic are made of clay and marly clay with frequent intercalations of sands and sandstones in a thick package, belonging Sarmatian, respectively, Volhinian and Basarabian, which directly influences the characteristics of the parent material of the soil.In this way, due to differences in altitude, these soils were formed and evolved deposits vary in granulometric composition, it is represented by loess, loess-like deposit, loam and loess, marly clay.Thus, we believe that the presence greyic phaeozems of our country in eastern, the genesis and evolution of the important role they have parental materials rich in fine sand fraction (31-41%). Specific these soils is the formation of humic acids and precipitate in place, under the influence of calcium ions, contributing to the development and the individualization of the horizon Am.Fulvic acids from the breakdown of litter cvercinee does not precipitate in the upper horizon, but migrate to the base, they favoring the migration is known as the iron and aluminum hydroxides and enriching the waste in the lower part of the quartz diagnostic horizon for greyic phaeozems, and a clay horizon B argic migrated upper horizon.

Common evidence gaps in point-of-care diagnostic test evaluation: a review of horizon scan reports

ObjectiveSince 2008, the Oxford Diagnostic Horizon Scan Programme has been identifying and summarising evidence on new and emerging diagnostic technologies relevant to primary care. We used these reports to determine the sequence and timing of evidence for new point-of-care diagnostic tests and to identify common evidence gaps in this process.DesignSystematic overview of diagnostic horizon scan reports.Primary outcome measuresWe obtained the primary studies referenced in each horizon scan report (n=40) and extracted details of the study size, clinical setting and design characteristics. In particular, we assessed whether each study evaluated test accuracy, test impact or cost-effectiveness. The evidence for each point-of-care test was mapped against the Horvath framework for diagnostic test evaluation.ResultsWe extracted data from 500 primary studies. Most diagnostic technologies underwent clinical performance (ie, ability to detect a clinical condition) assessment (71.2%), with very few progressing to comparative clinical effectiveness (10.0%) and a cost-effectiveness evaluation (8.6%), even in the more established and frequently reported clinical domains, such as cardiovascular disease. The median time to complete an evaluation cycle was 9 years (IQR 5.5–12.5 years). The sequence of evidence generation was typically haphazard and some diagnostic tests appear to be implemented in routine care without completing essential evaluation stages such as clinical effectiveness.ConclusionsEvidence generation for new point-of-care diagnostic tests is slow and tends to focus on accuracy, and overlooks other test attributes such as impact, implementation and cost-effectiveness. Evaluation of this dynamic cycle and feeding back data from clinical effectiveness to refine analytical and clinical performance are key to improve the efficiency of point-of-care diagnostic test development and impact on clinically relevant outcomes. While the ‘road map’ for the steps needed to generate evidence are reasonably well delineated, we provide evidence on the complexity, length and variability of the actual process that many diagnostic technologies undergo.

Main Feedbacks Between Oxidizable Carbon Content and Selected Soil Characteristic of Chernozem

Anthropogenic pressure on our agricultural land is culminating last hundred years, especially after 1948, not only because of only massive application of mineral fertilizers but also because of land consolidation and subsequent accelerated water and wind erosion and use of mechanization. This article focuses on main demonstration of feedbacks especially with oxidizable carbon which can negatively affect soil as a homeostatic system. Oxidizable carbon, as the basis of soil humus, is crucial for maintaining soil fertility and for its resistance to further degradation factors affecting the soil. 35 chernozem sites were selected in South Moravia region. These soils had been probably used for their fertility and availability before the turn of the AD. Unfortunately, their long-term agricultural use has resulted in adverse impact on their quality.This way, shallower forms of erosion were often formed. These erosion forms are omitted for the purposes of our study there. For this work, locations with preserved chernic (i.e. diagnostic) horizon, as the horizon with less anthropogenic influence, were selected. Relations between a grain size (clay, silt and sand particles), exchange reaction in soil, sorption capacity, oxidizable carbon content, total nitrogen content and content of selected potentially acceptable elements (Ca, Mg) were monitored.

Analysis of “Systematics of Polish Soils”

The “Systematics of Polish Soils” (SgP, 2011) is very close to WRB and “Soil Taxonomy”. The morphological characteristics of the soils, investigated in the field, rather than soil genesis are diagnostic criteria. The main provisions of the new “Systematics”, properties of soils of higher taxonomic levels have been reviewed. Some diagnostic horizons, which were not borrowed from other classifications, have been described. We tried to find equivalents in the Ukrainian classification for some soils names. The correlation of Poland soils and WRB has been analyzed. Key words: Systematics of Polish Soils, classification, order, soil type, diagnostic horizon, WRB.