Lúcia Helena Cunha dos Anjos

Propriedades químicas e biológicas de solo de tabuleiro cultivado com cana-de-açúcar com e sem queima da palhada

Two systems of sugar cane harvesting were compared: 1-previous burning (burned cane) and 2-straw spreading over the soil surface (green cane), over an area of Linhares Agropecuaria S.A. plantation, in Linhares, Espirito Santo, Brazil. The soil was classified as Yellow Podzolic sandy over medium texture, developed from Barreiras Formation sediments. After six years of sugar cane cultivation (1989-1994), nutrient distribution, humified fractions, and soil microbial biomass dynamics were determined. The green cane system showed an increasing of soil carbon content in the 0-20 cm soil depth, as well as higher levels of exchangeable magnesium when compared to the burned cane system. However, the burned cane system had the highest levels of potassium and phosphorus in the surface layer. The straw addition resulted in the predominance of humin and fulvic acid fractions and of a greater portion of carbon immobilized in the soil microbial biomass, mainly in the 0-5 cm soil depth, with the highest values observed in the rainy season (November).

Sistemas de colheita da cana-de-açúcar e alterações nas propriedades físicas de um solo podzólico amarelo no Estado do Espírito Santo

A long term (1989-1994) experiment with sugar cane (RB 739735) was carried out, in Linhares, ES, Brazil, in order to evaluate the effect of two systems of sugar cane harvesting: the first with previous burning (burned cane), and the second with crop residue remaining on the soil surface (green cane), on some physical properties of a tableland Yellow Podzolic soil. The statistical design was in randomized blocks, replicated six times. After six years of cultivation, a process of soil degradation was observed in the burned cane system, with decreasing of aggregate mean diameter and increasing of soil bulk density at the 0-5 cm soil depth. There were also differences in total porosity and porous distribution at the 0-5 cm soil depth as a consequence of the harvesting system. The soil water infiltration, measured in the field, was greatest in the area under the green cane treatments. The same result was not observed when measuring saturated hydraulic conductivity with the steady state permeameter.

Adsorção de fósforo em solos de argila de atividade baixa

ABSTRACT PHOSPHATE SORPTION IN LOW ACTIVITY CLAY SOILS In this study possible correlations between physical and chemical properties and the maximumphosphorus adsorption capacity (MAPC) were evaluated in soils with low activity clay from differentregions of Brazil, using samples from the surface (A) and subsurface (B) horizons of 16 soil profiles. Thedosages for the determination of MAPC were calculated from the level of remaining phosphorus andthey ranged from 0 to 135 mg L -1 . From this data isotherms of P adsorption were built. Correlationswere tested between MAPC and the clay content, organic carbon, ki, kr, specific surface, Al contentdetermined by sulfuric acid attack, and content of different forms of extracted iron. A high variation inthe values of MAPC for the surface horizon (48 to 1429 mg kg -1 ) and for the subsurface horizon (455 to1667 mg kg -1 ) was observed. The correlation coefficients showed a significant association between MAPCand clay content, iron and aluminium determined by sulfuric acid attack and iron extracted by dithionite-citrate-bicarbonate (DCB). The multiple regression analysis showed a good fit to MAPC values based insoil attributes.

Topography and spatial variability of soil physical properties

Among the soil formation factors, relief is one of the most used in soil mapping, because of its strong correlation with the spatial variability of soil attributes over a landscape. In this study the relationship between topography and the spatial variability of some soil physical properties was evaluated. The study site, a pasture with 2.84 ha, is located near Seropedica, Rio de Janeiro State, Brazil, where a regular square grid with 20 m spacing was laid out and georreferenced. In each sampling point, altitude was measured and undisturbed soil samples were collected, at 0.0-0.1, 0.1-0.2, and 0.2-0.3 m depths. Organic carbon content, soil texture, bulk density, particle density, and soil water retention at 10 (Field Capacity), 80 (limit of tensiometer reading) and 1500 kPa (Permanent Wilting Point) were determined. Descriptive statistics was used to evaluate central tendency and dispersion parameters of the data. Semivariograms and cross semivariograms were calculated to evaluate the spatial variability of elevation and soil physical attributes, as well as, the relation between elevation and soil physical attributes. Except for silt fraction content (at the three depths), bulk density (at 0.2-0.3 m) and particle density (at 0.0-0.1 m depth), all soil attributes showed a strong spatial dependence. Areas with higher elevation presented higher values of clay content, as well as soil water retention at 10, 80 and 1500 kPa. The correlation between altitude and soil physical attributes decreased as soil depth increased. The cross semivariograms demonstrated the viability in using altitude as an auxiliary variable to improve the interpolation of sand and clay contents at the depth of 0.0-0.3 m, and of water retention at 10, 80 and 1500 kPa at the depth of 0.0-0.2 m.

Concentrações naturais de metais pesados em algumas classes de solos brasileiros

ABSTRACT NATURAL CONTENTS OF HEAVY METALS IN SOME BRAZILIAN SOIL CLASSESThe heavy metals background levels for evaluation of a possible contamination are still notdefined in Brazilian soils. The objective of this study was to measure the content of the heavymetals Cd, Cr, Cu, Fe, Mn, Ni, Zn, in several brazilian soils, under natural conditions, and to correlatesome soil properties with the occurrence of these elements. Soil samples from EMBRAPA Soils’ (RJ)collection were used (162 in total), corresponding to A and B (or C) horizons from 81 profiles, of themain classes of Brazilian soils, especially Ultisols (Argissolos) - 27% and Oxisols (Latossolos) - 42%.Heavy metal levels were determined using an ICP-AES, after extraction with acqua regia. Theaverage metal concentrations were below average values reported in the literature for soils foundabroad, with exception to Cd. They were also lower than values considered toxic to plants, includingCd values. Soil samples were clustered by similarity, based on the variables content of clay, silt,Mn, and Fe, and value of soil CEC (T value). This enabled separation of the soil samples in sevengroups which have distinct ranges for the soil variables contents, which allowed an estimation ofthe heavy metals background levels for soil samples with characteristics within the range of each group.

Atributos químicos e físicos de um Argissolo Vermelho-Amarelo em sistema integrado de produção agroecológica

The objective of this study was to evaluate the influence of agroecological management systems on physical and chemical attributes of an Udult soil. The following areas were selected: conventional tillage (corn/beans); no tillage (eggplant/corn); consortium of passion fruit/Desmodium sp.; fig cultivation; and an agroforestry system (AFS). The undisturbed soil samples were taken from two layers (0-5 and 5-10 cm) and in two periods, the summer of 2005 and the winter of 2006. The soil properties analyzed were: bulk density (Ds), total pore volume, mean weight diameter (MWD) and mean geometric diameter (MGD) of aggregates, pH, Al, Ca+Mg, K, H+Al, P, and total organic carbon (TOC). The highest values of Ds, P and K were observed in the fig area. The system with corn/beans had the lowest MWD and MGD values. The highest values of MWD and MGD were observed in the passion fruit/Desmodium and eggplant/corn systems. Differences in TOC were greater at the 5-10 cm depth. Soil in the AFS had the highest percentage of total porosity. The analysis of main components showed that the area cultivated with fig had the highest soil fertility.

Proposição de valores de referência para a concentração natural de metais pesados em solos brasileiros

Para avaliar a extensao da poluicao de uma area, e comum se comparar os teores totais de metais pesados encontrados num dado solo com aqueles defrontados em condicoes naturais (nao poluidos) ou com valores de referencia (padroes). Propuseram-se atraves deste estudo: 1) valores de referencia (VR) e limites de tolerância (LT) para os mais representativos solos brasileiros, e 2) um modelo para obtencao das concentracoes naturais de Cd, Co, Cr, Cu, Ni, Pb e Zn em um solo, a partir dos teores de silte, argila, Mn, Fe e CTC. Reuniram-se 256 amostras de solo por similaridade, em sete grupos e se calcularam as concentracoes correspondentes ao quartil superior dos dados. Essas concentracoes sao propostas como valores de referencia (VR) em solos brasileiros; alem disso, obtiveram-se os limites de tolerância (LT) para cada grupo a partir da expressao antilog (m + 2s), cujos m (media) e s (desvio padrao) dos dados foram transformados em log10. As funcoes de classificacao da analise discriminante mostraram se apropriadas para alocar novas amostras nos grupos estabelecidos. Assim, e possivel avaliar solos sob atividade antropica e saber se ha motivo para suspeitar de que a area esteja poluida.

ANÁLISE DOS COMPONENTES PRINCIPAIS E MÉTODOS MULTICRITÉRIO ORDINAIS NO ESTUDO DE ORGANOSSOLOS E SOLOS AFINS

One important property of Organosols (Histosols) (and soils with high content of organic carbon) to predict use potential and degradation risks is the degree of subsidence (loss of mass and volume). In Organosols the subsidence risks vary according to the soil attributes, mainly the nature of organic matter and deposition environment. In this paper we studied 19 soil profiles from different parts of the country, collected and described according to procedures recommended by the SBCS (Brazilian Soil Science Society); the analytical methods proposed by EMBRAPA-Solos were used to characterize the soils. The principal component analysis was used to cluster the profiles based on morphological, physical, chemical and environmental attributes and proved adequate to group the soils under study based on the profile attributes and the grouping was well related to their taxonomy. The soil profiles were ranked by the ordinal multicriteria methods of Border, Condorcet and Copeland based on the subsidence risk. Results indicated a correlation between the methods (with exception of the Condorcet approach, unsuitable to rank the alternatives) and the minimum residue, which is the classical parameter for the evaluation of subsidence, indicating efficacy to rank/classify the soil profiles in relation to subsidence risk. The quantitative approaches used are promising as evaluation tools in soil science studies.

Formation of soils with plinthite on a toposequence in Maranha˜o State, Brazil

Abstract Soils with plinthite and ironstone concretions are extensive in Maranha˜o State, northeastern Brazil. They formed from the Fe-rich Itapecuru sandstone in a tropical subhumid climate with distinct wet and dry seasons. Most plinthic soils in Brazil have properties associated with low-activity clays, but these soils were reported to have properties associated with high-activity clays. The main objectives of this study were to characterize the chemical and mineralogical properties of the soils and to deduce the processes of their formation in relation to hillslope position. six soils were sampled, two each on summit, shoulder, and footslope positions. They were analyzed by standard characterization methods and by X-ray diffraction and infrared spectroscopy. The parent sandstone bedrock contained mainly quartz, feldspars, muscovite, biotite, and resistant minerals in the sand fraction, and smectite, mica and kaolinite in the clay fraction. The main Fe-oxide mineral was hematite. Most soil horizons had lower Fe concentrations than the sandstone parent material. Kaolinite, mica and quartz occurred in the coarse clay fraction of all pedons. Soils on the summit positions (Ustic Dystropept and Typic Ustorthent) lacked redoximorphic features, lacked plinthite, had the highest cation exchange capacity, and showed the weakest development. They were rich in smectite, probably inherited from the parent material, and goethite. soils on shoulder positions (Inceptic Plinthustult and Plinthic Dystropept) had the largest concentration of total Fe, mostly as goethite. Those on footslopes (Typic Plinthaquult and Plinthic Paleaquult) exhibited the most redoximorphic features and had horizons in which the Fe was strongly concentrated in ironstone and plinthite, mostly as lepidocrocite and goethite. The crystallinity of these minerals increased from non-plinthic material to plinthite to ironstone concretions. They formed as the hematite in the sandstone weathered. These soils are less weathered than most plinthic soils of Brazil. Diagnostic criteria for some subgroups of the Plinthustult and Dystropept great groups of soil Taxonomy and some new classes for the Brazilian soil Classification system were proposed.

Agregação, carbono e nitrogênio em agregados do solo sob plantio direto com integração lavoura‑pecuária

The objective of this work was to evaluate the stability of aggregates, light organic matter content (LOM), distribution of total organic carbon (TOC) and nitrogen (N) contents, and natural abundance of 13C and 15N in aggregates of a clayed Oxisol under no-tillage (NT) with crop-livestock integration (CLI), in comparison to an area under NT without CLI, and an area of natural Cerrado, in Montividiu, GO, Brazil. Soil samples were collected at the layers of 0-5 and 5-10 cm, in a completely randomized block design. The mass distribution of aggregates, mean weight diameter (MWD), geometric mean diameter (GMD), and LOM were evaluated, and the levels of TOC, N, δ13C and δ15N aggregates were quantified. The Cerrado area had the highest values of MWD, GMD and LOM. The NT-CLI showed higher values of MWD, GMD, TOC, N and LOM in the layer of 5-10 cm than the area of NT without brachiaria. The NT-CLI increased the indices of soil aggregation (0-5 and 5-10 cm), the levels of LOM (5-10 cm), TOC and N (0-5 cm) and the formation of water-stable aggregates (5-10 cm) in comparison to the NT without palisade grass.