Alberto Vasconcellos Inda Junior

Variáveis relacionadas à estabilidade de complexos organo-minerais em solos tropicais e subtropicais brasileiros

A estabilidade de complexos organo-minerais e uma caracteristica importante quanto a quimica e fisica de solos tropicais e subtropicais. O objetivo deste estudo foi identificar variaveis relacionadas a estabilidade de complexos organo-minerais, avaliada pela energia de ultra-som necessaria para a dispersao total do solo em particulas primarias, em seis solos das regioes Sul e Centro-Oeste do Brasil com textura e mineralogia distintas. A energia de ultra-som necessaria para dispersao total dos solos variou de 239 a 2.389J mL-1, sendo diretamente relacionada aos teores de carbono orgânico (R2=0,799, P<0,05). A mineralogia da fracao argila teve um papel determinante na estabilidade dos complexos organo-minerais, a qual foi relacionada aos teores de oxidos de ferro de baixa cristalinidade (R2=0,586, P<0,10), mas nao teve relacao com os teores totais de oxido de ferro pedogenicos. A analise qualitativa da fracao argila, realizada por difratometria de raios-X, demonstrou que a estabilidade dos complexos organo-minerais variou positivamente em funcao das proporcoes de gibbsita e de goethita na fracao argila, o que reforca o papel desses minerais na protecao fisica e estabilidade coloidal da materia orgânica em solos tropicais e subtropicais.

Digital soil mapping using multiple logistic regression on terrain parameters in southern Brazil

Soil surveys are necessary sources of information for land use planning, but they are not always available. This study proposes the use of multiple logistic regressions on the prediction of occurrence of soil types based on reference areas. From a digitalized soil map and terrain parameters derived from the digital elevation model in ArcView environment, several sets of multiple logistic regressions were defined using statistical software Minitab, establishing relationship between explanatory terrain variables and soil types, using either the original legend or a simplified legend, and using or not stratification of the study area by drainage classes. Terrain parameters, such as elevation, distance to stream, flow accumulation, and topographic wetness index, were the variables that best explained soil distribution. Stratification by drainage classes did not have significant effect. Simplification of the original legend increased the accuracy of the method on predicting soil distribution.

Solos subtropicais de altitude: atributos químicos, teor de matéria orgânica e resistência à oxidação química

In this research, texture, soil pH, CEC at pH 7, exchangeable Al, and content of Fe-oxides (Fed and Feo) were determined in A horizons samples of eight representative soils under native pasture from Campos de Cima da Serra, Rio Grande do Sul State, Brazil. The samples were treated with hydrogen peroxide and, before and after the treatment, C and N contents were determined and Fourier Transformed Infrared (FTIR) spectroscopy was performed. The content of soil C was high (4 to 23%) and its variation correlated with the altitude and exchangeable Al indicating that lower temperatures and complexation with ionic Al contribute to soil organic matter (SOM) stabilization. The proportion of oxidation-resistant carbon varied between 1 and 16% and correlated with the ratio Feo/Fed. The stabilization of this SOM fraction was assigned to the interaction of carboxylic groups bound to aromatic and aliphatic structures with Fe-oxides of low crystallinity degree.

Ação dos térmitas no solo

ABSTRACT The order Isoptera is well known by its potential asa plague, although the number of species that are plagues issmall within the group. Termites are the dominant invertebratesin tropical terrestrial environments and are spread from tropicalrainforests to the savannahs, being found even in arid regions,in various habitats. These insects have a major role and arestill little studied in tropical ecosystems. Nutrient cycling,aeration, water infiltration of soil, bioturbation, aggregatesformation and organic material decomposition, are processesinfluenced by the action of termites, which , directly or indirectly,affect soil and landscape formation wherever they are. Wesuggest that a better approach must be addressed in futureresearches about these insects influence in the soil underspecified conditions of use and management, in sustainablefood production and climate changes . Key words : Isoptera, termite activity, soil biology, bioturbation,plague-termites . INTRODUCAO A importância ecologica dos isopteros emecossistemas tropicais e grande, principalmente quandoconsideradas as modificacoes que podem causar noambiente, desde alteracoes no aspecto visual dapaisagem, pela construcao de seus ninhos, alem dealteracoes da topografia, como dos microrrelevos demurundus, ate modificacoes nas propriedades fisicase quimicas do solo, efeitos no processo dedecomposicao, ciclagem de nutrientes, entre outros(HOLT & LEPAGE, 2000). Os cupins (termitas) sao amais importante fauna do solo nos tropicos quentessazonalmente secos (LOBRY DE BRUYN &CONACHER, 1990), sendo fundamentais para ofuncionamento do ecossistema, pois ocupam niveistroficos na cadeia alimentar do solo (SILVA et al., 2007).Os termitas sao reconhecidos como “engenheiros doecossistema” (DANGERFIELD et al., 1998), devido ahabilidade que possuem de modificar a estrutura do

Estimativa do benefício econômico potencial de dois levantamentos de solos no Estado do Rio Grande do Sul

This study applies decision analysis techniques for the qualification of economic value of the a high intensity Soil Survey of Sentinela do Sul County, RS, Brazil (scale 1:50,000) and a soil survey of the Charcoal Basin of the Jacui River, RS, Brazil (Scale 1:100,000), using economic information related to the major regional crops and soil survey quality. The determination of the economic value is made by quantifying the increase in economic return when land use planning uses soil survey information. Results of this evaluation highlight the economic benefits generated by the use of soil survey information (R

Características de solos construídos após mineração de carvão relacionadas ao processo de construção e à composição do material utilizado

153,15 ha-1 e R

Cinética da dissolução redutiva da goethita e hematita em solos poligenéticos

70.15 ha-1, respectivelly for a 1:50,000 map and for a 1:100,000 map) are larger that soil survey costs (R

Soil susceptibility to compaction under use conditions in southern Brazil

1.03 ha-1 for a 1:50,000 map and R

Strength attributes and compaction susceptibility of Brazilian Latosols.

0.38 ha-1 for a 1:100,000 map).

Variabilidade de goethita e hematita via dissolução redutiva em solos de região tropical e subtropical

Coal stripmining involves the removal of upper soil and geological layers, which must be relocated in a similar way that in the original profile when reconstructing the landscape. As this process changes soil and landscape characteristics, this study evaluated changes related to composition of materials and construction process in soils reconstructed 2 and 24 years ago, in Boa Vista Coal Mining, in Minas do Leao, Rio Grande do Sul, Brazil. The construction processes were evaluated by morphologic characteristics, soil density, saturated hydraulic conductivity, soil water infiltration capacity, particle size distribution, cation exchange capacity, carbon content, and neutralization and acidification potential. In both reconstructed areas, the construction process increased soil density and reduced both saturated soil hydraulic conductivity and soil water infiltration. No significant difference was found between sample sets of 2 and 24 years for particle size distribution, cation exchange capacity and carbon content, indicating that construction processes and the materials were similar. The decrease of neutralization and acidification potentials in soils built 24 years ago indicated an increase in sulfurization as time since soil reconstruction increases. Due to alterations in soils, both areas present serious limitations for vegetation development, influencing negatively the recovery of mining sites and adjacent areas.