Use of General Purpose Adsorption Isotherms for Heavy Metal–Clay Mineral Interactions

Latosols (Oxisols) under cerrado vegetation have been intensively incorporated into the agricultural production process. However, studies involving soil quality in this environment are scarce. The objective of this work was to verify alterations on aggregation attribute indicators of soil quality, as a result of the management systems adopted for the native cerrado, and to select the best attributes indicating such alterations. The samples were collected at depths of 0-10, 10-20, and 20-40 cm from a typic Dystrophic Red Latosol (Oxisol) in Morrinhos, Goias State, Brazil. The following attributes were evaluated: mean geometric diameter (MGD), percentage of aggregates > 2 mm, percentage of aggregates 2 mm aggregate class (0.852*), and a negative correlation (-0.903**) with the 2 mm- and < 0.25 mm-aggregate groups were good indicators for alterations in relation to the native cerrado and can be suggested as useful components for the elaboration of a regional soil quality index.

/pdf/atributos-biologicos-indicadores-da-qualidade-do-solo-em-29ommai4gj.pdf

Atributos biológicos indicadores da qualidade do solo em sistemas de manejo na região do cerrado no sul do estado de Goiás

The objective of this work was to verify alterations on the amounts and storage of organic carbon and total nitrogen of the soil, and on the nitric and ammonium forms, in management systems implemented in an area under native cerrado. Samples were collected at Morrinhos, Goias, Brazil, in a clayey, typic, dystrophic Red Latosol (Oxisol), from five depths, in the systems: native cerrado, Brachiaria sp. pasture, irrigated no-till with corn-beans crop rotation, irrigated no-till with corn-beans and rice-tomato for industry crop rotation, long-term conventional till and recent conventional till following pasture. There were no significant differences on the level, and on carbon and total nitrogen storage of the soil. However, the long-term conventional till presented negative variations on carbon storage in relation to the native cerrado system up to 20 cm depth, unlike the systems with less soil movement. The ammonium predominated in the native cerrado and pasture systems through the soil profile, whereas the nitrate amounts were higher in the superficial layer of the soil in the systems with annual crops. The pasture and no-till, on condition of diverse crop rotation, are prominent systems in terms of increasing the organic carbon storage of the soil.

https://www.scielo.br/pdf/pab/v39n2/19853.pdf

Estoque de carbono e nitrogênio e formas de nitrogênio mineral em um solo submetido a diferentes sistemas de manejo

Objetivou-se, com este estudo, avaliar a qualidade estrutural de um Latossolo Roxo, pelos seguintes atributos: distribuicao do tamanho dos agregados, diâmetro medio geometrico dos agregados, resistencia dos agregados ao impacto das gotas de chuva simulada, e resistencia a penetracao, em sistemas de plantio direto e cultivo convencional, tendo como testemunha a floresta nativa. Entre os metodos utilizados, a energia cinetica necessaria para destruir os agregados foi a que proporcionou maior discriminacao entre os sistemas de manejo estudados. Na camada superficial, o sistema plantio direto propiciou agregados maiores e mais resistentes, e os valores do diâmetro medio geometrico e a energia cinetica necessaria para destruir agregados foram cerca de 1,37 e 2,4 vezes maiores do que no cultivo convencional, respectivamente. Valores criticos de resistencia a penetracao foram observados no que diz respeito ao cultivo convencional e ao plantio direto, na camada de 5-20 cm de profundidade. Por outro lado, na camada de 0-5 cm, o plantio direto apresentou valor baixo de resistencia a penetracao, o que esta relacionado com seu teor elevado de materia orgânica e com material vegetal em decomposicao na superficie do solo. Estes aspectos ressaltam o efeito benefico deste sistema, pois contribuem para o manejo sustentado do solo.

/pdf/sistemas-de-manejo-e-qualidade-estrutural-de-latossolo-roxo-1rx5fbp7um.pdf

Sistemas de manejo e qualidade estrutural de Latossolo Roxo

Fe-containing pillared clays as catalysts for phenol hydroxylation

The constant consideration, punctuated by periods of almost frantic concentration of effort and by periods of dull lassitude, given to chemically bonding soil particles into structural materials has yielded some useful products, some laboratory curiosities, and some ideas as to how current and future efforts may be more meaningfully evaluated Current work indicates that attempts to evaluate chemicals for bonding clay soils are significantly clouded by: (1) lack of knowledge of the soil-chemical bond; (2) lack of knowledge of the type of soil surface susceptible to bonding; (3) lack of knowledge of the inhibitors to chemical reactions present in soil systems; (4) lack of a correlation of the differences in response to treatment between readily indentifiable clays and soil fractions apparently composed of these clays; and (5) lack of satisfactory laboratory techniques by which rapidly reacting chemicals can be properly incorporated with soils A program is proposed whereby standards of response to treatment are established for different categories of known bonding agents when used with fractionated silica, kaolin and kaolinitic soils, montmorillonite and montmorillonitic soils A device suitable for laboratory use in this program is suggested

V. H. Rodes

Papers

Method of Screening Chemical Bonding Agents for Clay Soils