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Resumen en: The aim of this study was a survey of the estimated costs of soil erosion, an issue of fundamental importance in view of the current worldwide discussion...

http://www.redalyc.org/pdf/1802/Resumenes/Abstract_180218547001_2.pdf

Revista Brasileira de Ciência do Solo

Environmental factors affecting n2 fixation in grain legumes in the tropics, with an emphasis on brazil

Biochar is increasingly being recognized by scientists and policy makers for its potential role in carbon sequestration, reducing greenhouse gas emissions, renewable energy, waste mitigation, and as a soil amendment. The published reviews on biochar application to soil have so far focused mainly on the agronomic benefits, and have paid little attention to the potential unintended effects. The purpose of this chapter is to provide a balanced perspective on the agronomic and environmental impacts of biochar amendment to soil. The chapter highlights the physical and chemical characteristics of biochar, which can impact on the sorption, hence efficacy and biodegradation, of pesticides. As a consequence, weed control in biochar-amended soils may prove more difficult as preemergent herbicides may be less effective. Since biochars are often prepared from a variety of feedstocks (including waste materials), the potential introduction of contaminants needs to be considered before land application. Metal contaminants, in particular, have been shown to impact on plant growth, and soil microbial and faunal communities. Biochar has also been shown to influence a range of soil chemical properties, and rapid changes to nutrient availability, pH, and electrical conductivity need to be carefully considered to avoid unintended consequences for productivity. This chapter highlights some key areas of research which need to be completed to ensure a safe and sustainable use of biochar. In particular, understanding characteristics of biochars to avoid ecotoxicological impacts, understanding the effects of biochar on nutrient and contaminant behavior and transport, the effects of aging and the influence of feedstock and pyrolysis conditions on key properties are some of the areas that require attention.

Biochar Application to Soil: Agronomic and Environmental Benefits and Unintended Consequences

“ No other single chemical soil characteristic is more important in determining the chemical environment of higher plants and soil microbes than the pH There are few reactions involving any component of the soil or of its biological inhabitants that are not sensitive to soil pH This sensitivity must be recognized in any soil-management system” “ Lime is truly a foundation for much of modern humid-region agriculture Knowing how pH is controlled, how it influences the supply and availability of essential plant nutrients as well as toxic elements, how it affects higher plants and human beings, and how it can be ameliorated is essential for the conservation and sustainable management of soils throughout the world” (Brady and Weil, 1999) Under areas where rainfall exceeds evapotranspiration, soil acidification is an ongoing natural process, which can either be accelerated by the activity of plants, animals and humans or can be impeded by careful management practices In areas affected by industrial activities, soil acidification is caused by acid drainage from pyrite oxidation and also from acid precipitation In areas that remain unaffected by industrial pollution, soil acidification in managed ecosystems is mainly caused by the release of protons (H + ) during the transformation and cycling of carbon (C), nitrogen (N) and sulfur (S) Just like in managed ecosystems, soil acidification in natural ecosystems caused by acid drainage and acid precipitation can have adverse impacts where soils have low pH buffering capacity Liming is the most common management practice aimed at neutralizing the acid produced, thereby overcoming the adverse impacts of soil acidification This review brings together fundamental aspects of soil acidification and recent developments on the implications of liming in relation to soil processes, particularly nutrient and heavy metal transformation and bioavailability in soils The article first outlines the various soil, plant and microbial processes that generate acid (protons; H + ions) both under natural and managed ecosystems It then discusses the effects of soil acidity on soil chemical and biological properties The effect of liming to overcome the problems associated with soil acidity is examined in relation to the transformation of nutrient ions and heavy metals The practical implications of liming to overcome heavy metal toxicity have been discussed in relation to the adsorption, leaching and phytoavailability of these metal ions Future research should aim to focus on the development of methods to quantify lime-enhanced (im)mobilization of nutrient ions and heavy metals in soils and to explore further the role of liming in remediating contaminated soils

Soil acidification and liming interactions with nutrientand heavy metal transformationand bioavailability

Liming represents a management procedure that can affect the soil structure and its thermodynamic processes. In this context, the aims of this study were to assess (i) the effects of the surface and incorporated liming on the clay dispersion, soil water availability, and aeration capacity; (ii) the influence of soil chemical alterations in its physical attributes. For this, a field experiment was installed in a family farming property, located in the southeastern region of the State of Parana, in a Dystrudept soil. The treatments were 3 application modes (on the surface, incorporated via plowing and incorporated via subsoiling and harrowing), with and without 15 Mg∙ha–1 of lime, aiming to increase the base saturation in the topsoil (0 – 0.20 m) to approximately 70%. Eighteen months after application, undisturbed and disturbed soil samples were collected from the 0 – 0.10 and 0.10 – 0.20 m layers to evaluate the waterdispersed clay (WDC), water content at the field capacity (θFC) and at the permanent wilting point (θPWP), plant available water capacity (PAWC), relative water capacity (RWC), aeration capacity (AC), granulometry and the soil structural and chemical attributes. WDC content in the 0 – 0.10 m layer increased when the soil was revolved and it was influenced exclusively when lime was applied on the soil surface. With surface liming there were increase in θFC, θPWP, PAWC and RWC, and reduction in AC in the 0 – 0.10 m layer. In the 0.10 – 0.20 m layer isolated effects were verified of the modes application and liming on θFC, PAWC and RWC, while θPWP was not influenced by treatments. The soil water availability and aeration capacity alterations were mainly affected by micro and macroporosity increases, pH reduction, Al3+ precipitation, and substitution of this ion in the exchange complex by Ca2+ and Mg2+.

/pdf/surface-and-incorporated-liming-effects-on-clay-dispersion-3j4zdb8wpq.pdf

Surface and incorporated liming effects on clay dispersion, water availability, and aeration capacity of a Dystrudept soil

Seed inoculation with Azospirillum brasilense and nitrogen fertilization for no-till cereal production

Detection of Azospirillum brasilense by qPCR throughout a maize field trial

Para avaliar os efeitos da calagem e da aplicacao de cobalto e molibdenio nas sementes sobre a concentracao de clorofila em folhas de plantas de amendoim, foram instalados experimentos, no periodo "das aguas", nos anos agricolas 1990/91 e 1991/92, em area de ocorrencia de Latossolo Vermelho-Escuro distrofico textura media. Foram utilizadas quatro doses de calcario dolomitico calcinado: 0, 4, 6 e 8 t ha-1; dois cultivares de amendoim: "Tatu" e "Tupa", e quatro tratamentos de sementes: nao tratadas, tratadas com cobalto, com molibdenio e com cobalto mais molibdenio. Verificou-se que, em condicoes de elevada acidez do solo, a aplicacao de molibdenio nas sementes aumentou a concentracao de clorofila nas folhas do amendoim, com efeito semelhante ao da calagem na ausencia de molibdenio. A concentracao de clorofila correlacionou-se positivamente com o teor de nitrogenio nas folhas, indicando que os efeitos da calagem e da aplicacao de molibdenio sobre a concentracao de clorofila foram basicamente ocasionados pela melhoria do processo de fixacao simbiotica do nitrogenio por maior atividade da nitrogenase. Houve aumento linear da producao de vagens e graos do cultivar "Tatu" com o aumento da concentracao de clorofila nas folhas e, no caso do cultivar "Tupa", a maxima producao de vagens e graos foi obtida para concentracao de clorofila nas folhas de 4,6 mg dm-2.

/pdf/efeitos-da-calagem-cobalto-e-molibdenio-sobre-a-concentracao-1yaxoi39gr.pdf

Efeitos da calagem, cobalto e molibdênio sobre a concentração de clorofila nas folhas de amendoim

The objective of this work was to determine the impact of phosphogypsum application on 226Ra and 228Ra activities in the soil and on their accumulation in soybean grains. A field experiment was carried out in Parana state, Brazil, on a loamy Typic Hapludox, under no-till system, with increasing phosphogypsum rates: 4, 8, and 12 Mg ha-1. GammA ray spectrometry was carried out using HPGe detectors with 45 and 10% relative efficiencies, for soybean grains and soil, respectively. No increment of 226Ra and 228Ra activities was observed due to the increase in phosphogypsum rates in the soil, and a small reduction was noticed in the grains. Average values found for 226Ra and 228Ra activities were 37 and 57 Bq kg-1 in the soil and 1.44 and 3.19 Bq kg-1 in soybean grains. The application of phosphogypsum for no-till soybean production is a safe practice regarding the risks of radiation damage to human health

/pdf/radiological-impact-of-phosphogypsum-surface-application-in-36b5ctla4u.pdf

Eduardo Fávero Caires

Papers

Surface and incorporated liming effects on clay dispersion, water availability, and aeration capacity of a Dystrudept soil

Seed inoculation with Azospirillum brasilense and nitrogen fertilization for no-till cereal production

Detection of Azospirillum brasilense by qPCR throughout a maize field trial

Efeitos da calagem, cobalto e molibdênio sobre a concentração de clorofila nas folhas de amendoim

Radiological impact of phosphogypsum surface application in a no-till system in Southern Brazil