Atributos de solo determinantes para a estimativa do índice de estabilidade de agregados

The objective of this work was to identify the most important soil attributes to estimate the aggregate stability index. To identify these attributes, multiple stepwise regression was used on data collected from anEutrorthox cultivated under a no‑tillage system. To obtain the prediction models for the aggregate stability index (IeaE), ten independent variables were evaluated: total clay, bulk density, penetration resistance, organic matter, pH in water, effective cation exchange capacity, available water, total porosity, macroporosity, and gravimetric moisture. The attributes total clay (Arg), bulk density (Ds), penetration resistance (RP), organic matter (MO), and pH are the most important for the estimation of the IeaE, and the pedotransfer function that best describes this index is: IeaE = 27.80 + 0.04Arg + 27.97Ds + 12.35RP + 0.45MO ‑ 9.72pH (R2 = 0.89).O objetivo deste trabalho foi identificar atributos de solo importantes para a estimativa do índice de estabilidade de agregados. Para a identificação dos atributos, utilizou-se a regressão múltipla “stepwise” em dados coletados de Latossolo Vermelho eutroférrico, cultivado em sistema de plantio direto. Para a obtenção dos modelos de estimativa do índice de estabilidade de agregados (IeaE), foram analisadas dez variáveis independentes: argila total, densidade do solo, resistência à penetração, matéria orgânica, pH em água, capacidade efetiva de troca de cátions, água disponível, volume total de poros, macroporosidade e umidade gravimétrica. Os atributos argila total (Arg), densidade do solo (Ds), resistência à penetração (RP), matéria orgânica (MO) e pH são os mais importantes para a estimativa do IeaE, e a função de pedotrânsferência que melhor descreve esse índice é: IeaE = 27,80 + 0,04Arg + 27,97Ds + 12,35RP + 0,45MO ‑ 9,72pH (R2 = 0,89)

Иловые растворы морских отложений в природной экосистеме шельфа Черного моря

Иловые растворы донных морских отложений рассматриваются как часть гидрохимической и экологической системы шельфа Черного моря. Они образуют нижнюю сероводородную (восстановительную) зону, которая подстилает кислородную (окислительную) зону моря. Иловые растворы влияют на эколого-гидрохимическую среду шельфа как источник поступления сероводорода, аммония, микроэлементов в придонный слой морской воды.Мулові розчини донних морських відкладів розглядаються як частина гідрохімічної та екологічної системи шельфу Чорного моря. Вони утворюють нижню сірководневу (відновлювальну) зону, яка підстелює кисневу (окислювальну) зону моря. Мулові розчини впливають на еколого-гідрохімічне середовище шельфу як джерело надходження сірководню, амонію, мікроелементів у придонний шар морської води.Silt solutions of seabed sediments are considered as a part of the hydrogeochemical and ecological system of the Black Sea shelf. They form the lower hydrogen sulphide (reducing) zone spreading under the oxygen (oxidizing) zone of sea water. Silt solutions have an influence on the ecohydrochemical medium of the shelf as a source of hydrogen sulphide, ammonia and microelements in to the ground layer of sea water

Qualidade física de latossolo com aplicação de lixiviado de aterro sanitário

The organic carbon present in the landfill leachate (LL) can improve the physical quality of the soil when applied in agricultural areas, minimizing the problem of disposal of this waste. The objective of this work was to evaluate the effect of the application of different doses of LL on the physical quality of the Red Latosol (Oxisol) after five years of applications. The treatment consisted of applications of LL in doses of 32, 65, 98 and 130 m3 ha-1 crop-1 and the treatment that receives mineral fertilizer. The physical quality of the soil was evaluated in soil samples collected in the layers 0.00-0.10 and 0.10-0.20 m, through the analysis of stability and diameter of the aggregates, soil density, total aeration capacity, field capacity and available water content. After five years of application of LL, at doses of 65, 98 and 130 m3 ha-1 crop-1 have promoted a linear increase of the aggregates with diameter greater than 2.00 mm, of the weighted average and geometric diameters and of the soil density, with a consequent reduction of the ratio between macro and micropores and the aeration capacity of the layers 0.00-0.10 and 0.10-0.20 m. After five years of these applications, the soils that received the dose of 32 m3 ha-1 crop-1 presented the best physical quality in relation to the other doses, since this dose did not promote an increase of the aggregates larger than 2 mm in the superficial layer (0.00-0.10 m) and was the dose with lower effect in the reduction of aeration of the soil, in relation to the others (65, 98 and 130 m3 ha-1 season-1) in the layers 0.00-0, 10 and 0.10 - 0.20 m.O carbono orgânico presente no lixiviado de aterro sanitário (LAS) pode melhorar a qualidade física do solo quando aplicado em áreas agrícolas, minimizando o problema de descarte desse dejeto. O objetivo do trabalho foi avaliar o efeito da aplicação de diferentes doses de LAS sobre a qualidade física de um LATOSSOLO VERMELHO Distroférrico após cinco anos de aplicações. Os tratamentos consistiram de aplicações de LAS nas doses de 32, 65, 98 e 130 m3 ha-1 safra-1 e um tratamento que recebe fertilizante mineral. A qualidade física do solo foi avaliada em amostras de solo coletadas nas camadas 0,00-0,10 e 0,10-0,20 m, por meio da análise da estabilidade e diâmetro dos agregados, densidade do solo, capacidade de aeração total, capacidade de campo e teor de água disponível. Após cinco anos de aplicações de LAS, nas doses de 65, 98 e 130 m3 ha-1 safra-1 promoveram aumento linear dos agregados com diâmetro maior que 2,00 mm, dos diâmetros médio ponderado e geométrico e da densidade do solo, com consequente redução da razão entre macro e microporos e da capacidade de aeração das camadas 0,00-0,10 e 0,10-0,20 m. Após cinco anos de aplicações de LAS, os solos que receberam a dose de 32 m3 ha-1 safra-1 apresentaram a melhor qualidade física em relação às demais doses, pois, essa dose não promoveu aumento dos agregados maiores que 2 mm na camada superficial (0,00-0,10 m) e foi a dose com menor influência na redução da aeração do solo, em relação às demais (65, 98 e 130 m3 ha-1 safra-1) nas camadas 0,00-0,10 e 0,10-0,20 m

Conservation agriculture practices adopted in southern Brazil

The adoption of conservation agriculture (CA) practices are essential for soil and water conservation. In CA, farmers must adopt no-tillage (NT) with crop rotation to maintain a permanent soil cover. In Brazil, mainly in the South region, for CA to be more efficient, practices such as contour farming and agricultural terraces should also be adopted. Thus, the objective of this study is to determine the extent to which NT has been adopted with crop rotation and others soil and water conservation practices. Data from the Agricultural Census in Paraná State, southern Brazil, were used. For the data analysis, the relationship between the level of adoption of NT and the use of crop rotation, contour farming and agricultural terraces was analyzed. A factor and cluster analysis were performed to distinguish regions in terms of soil and water conservation practices. The results show good overall soil and water conservation practices, although heterogeneity has been observed in the adoption practices between regions. Adoption of NT is high in almost all the studied regions. The conservation practice most widely used with NT is contour farming, whereas the least used is agricultural terraces. Conservation practices for runoff control are being neglected by farmers

Spatial variability of the physical quality of soil from management zones

International audienc

Modelling of soil penetration resistance for an oxisol under no-tillage

Soil penetration resistance is an important property that affects root growth and elongation and water movement in the soil. Since no-till systems tend to increase organic matter in the soil, the purpose of this study was to evaluate the efficiency with which soil penetration resistance is estimated using a proposed model based on moisture content, density and organic matter content in an Oxisol containing 665, 221 and 114 g kg-1 of clay, silt and sand respectively under annual no-till cropping, located in Londrina, Paraná State, Brazil. Penetration resistance was evaluated at random locations continually from May 2008 to February 2011, using an impact penetrometer to obtain a total of 960 replications. For the measurements, soil was sampled at depths of 0 to 20 cm to determine gravimetric moisture (G), bulk density (D) and organic matter content (M). The penetration resistance curve (PR) was adjusted using two non-linear models (PR = a Db Gc and PR' = a Db Gc Md), where a, b, c and d are coefficients of the adjusted model. It was found that the model that included M was the most efficient for estimating PR, explaining 91 % of PR variability, compared to 82 % of the other model