How accurate are pedotransfer functions for bulk density for Brazilian soils?

The aim of this study was to evaluate the performance of pedotransfer functions (PTFs) available in the literature to estimate soil bulk density (ρb) in different regions of Brazil, using different metrics. The predictive capacity of 25 PTFs was evaluated using the mean absolute error (MAE), mean error (ME), root mean squared error (RMSE), coefficient of determination (R2) and the regression error characteristic (REC) curve. The models performed differently when comparing observed and estimated ρb values. In general, the PTFs showed a performance close to the mean value of the bulk density data, considered as the simplest possible estimation of an attribute and used as a parameter to compare the performance of existing models (null model). The models developed by Benites et al. (2007) (BEN-C) and by Manrique and Jones (1991) (M&J-B) presented the best results. The separation of data into two layers according to depth (0-10 cm and 10-30 cm) demonstrated better performance in the 10-30 cm layer. The REC curve allowed for a simple and visual evaluation of the PTFs

SOLUBILIZAÃÃO DE PÃ DE BASALTO POR MEIO DE VINHAÃA: VARIAÃÃO DE pH E NUTRIENTES DISPONÃVEIS

O objetivo do trabalho foi avaliar o efeito da mistura de pó de basalto e vinhaça na alteração do pH e na disponibilização de elementos importantes para nutrição mineral de plantas, visando a aplicação desses materiais na adubação de solos, contribuindo para o aproveitamento de resíduos agroindustriais e de mineração. Foram realizados três ensaios (E1, E2 e E3). Em E1 e E2 foi avaliado o efeito da agitação no pH da mistura e em E3, em ensaio sem agitação, foram avaliadas a variação de pH e a liberação de íons solúveis importantes para nutrição de plantas. Os ensaios foram realizados em bancada, em três repetições, em erlenmeyers de 125 mL. Na comparação de E1 com E2 não houve efeito da agitação e não houve variação significativa do pH de misturas de vinhaça com pó de basalto. Em E3, ao final de 180 minutos de incubação, os teores de cálcio, ferro e manganês nas misturas de vinhaça e pó de basalto apresentaram aumentos significativos. Conclui-se que misturas de vinhaça e pó de rocha podem ser alternativa no aproveitamento de resíduos de mineração e da indústria sucroalcooleira, mas são necessários estudos para avaliar o efeito em solos e plantas

How accurate are pedotransfer functions for bulk density for Brazilian soils?

ABSTRACT: The aim of this study was to evaluate the performance of pedotransfer functions (PTFs) available in the literature to estimate soil bulk density (ρb) in different regions of Brazil, using different metrics. The predictive capacity of 25 PTFs was evaluated using the mean absolute error (MAE), mean error (ME), root mean squared error (RMSE), coefficient of determination (R2) and the regression error characteristic (REC) curve. The models performed differently when comparing observed and estimated ρb values. In general, the PTFs showed a performance close to the mean value of the bulk density data, considered as the simplest possible estimation of an attribute and used as a parameter to compare the performance of existing models (null model). The models developed by Benites et al. (2007) (BEN-C) and by Manrique and Jones (1991) (M&J-B) presented the best results. The separation of data into two layers according to depth (0-10 cm and 10-30 cm) demonstrated better performance in the 10-30 cm layer. The REC curve allowed for a simple and visual evaluation of the PTFs

Effect of rock powder and vinasse on two types of soils

Can vinasse accelerate the change of minerals in rock dust to obtain fertilizers, using residues from alcohol agro-industries and mining? Answering this question was the main objective of this study. Therefore, an experiment was set up in the laboratory in a completely randomized design using Polyvinyl Chloride (PVC) columns, in which the 0-50 cm layers of a clayey soil (eutroferric Red Oxisol) and sandy soil (Typic Quartzipsamment) were reproduced. We applied three different rates of basalt powder (0.0; 2.0, and 4.0 t ha-1) and one rate of vinasse (200 m³ ha-1) to the soils. The control was made by treatments with water (200 m³ ha-1) with the same rates of rock powder. Samples were first collected on the surface of each column (1, 15, 30, 45, 60, and 90 days after the application of vinasse and rock powder), and, at the end of the experiment, at the various depths and in leached water, to determine pH and the concentration of soluble Ca2+, Mg2+, and K+. There was a significant effect of the solvent and the soil on the surface layer, with higher concentrations found in the treatments with vinasse and in clayey soil, confirming the potential of vinasse to alter minerals in basalt powder. The resulting levels from the beginning to the end of the experiment suggest that sorption phenomena with neoformed mineral phases or organic acids may have occurred. It may be concluded that the use of rock powder and vinasse mixtures is a promising alternative for soil fertilization and recycling of waste from the sugarcane and mining industries

Effect of rock powder and vinasse on two types of soils

Can vinasse accelerate the change of minerals in rock dust to obtain fertilizers, using residues from alcohol agro-industries and mining? Answering this question was the main objective of this study. Therefore, an experiment was set up in the laboratory in a completely randomized design using Polyvinyl Chloride (PVC) columns, in which the 0-50 cm layers of a clayey soil (eutroferric Red Oxisol) and sandy soil (Typic Quartzipsamment) were reproduced. We applied three different rates of basalt powder (0.0; 2.0, and 4.0 t ha-1) and one rate of vinasse (200 m³ ha-1) to the soils. The control was made by treatments with water (200 m³ ha-1) with the same rates of rock powder. Samples were first collected on the surface of each column (1, 15, 30, 45, 60, and 90 days after the application of vinasse and rock powder), and, at the end of the experiment, at the various depths and in leached water, to determine pH and the concentration of soluble Ca2+, Mg2+, and K+. There was a significant effect of the solvent and the soil on the surface layer, with higher concentrations found in the treatments with vinasse and in clayey soil, confirming the potential of vinasse to alter minerals in basalt powder. The resulting levels from the beginning to the end of the experiment suggest that sorption phenomena with neoformed mineral phases or organic acids may have occurred. It may be concluded that the use of rock powder and vinasse mixtures is a promising alternative for soil fertilization and recycling of waste from the sugarcane and mining industries

Solubilization of diabase and phonolite dust by filamentous fungus

The objective of this study was to evaluate the effect of the fungus Aspergillus niger strain CCT4355 in the release of nutrients contained in two types of rock powder (diabase and phonolite) by means of in vitro solubilization trials. The experimental design was completely randomized in a 5 x 4 factorial design with three replications. It was evaluated five treatments (phonolite dust + culture medium; phonolite dust + fungus + culture medium; diabase powder + culture medium; diabase powder + fungus + culture medium and fungus + culture medium) and four sampling dates (0, 10, 20 and 30 days). Rock dust (0.4% w/v) was added to 125 mL Erlenmeyer flasks containing 50 mL of liquid culture medium adapted to A. niger. The flasks were incubated at 30°C for 30 days, and analysis of pH (in water), titratable acidity, and concentrations of soluble potassium, calcium, magnesium, zinc, iron and manganese were made. The fungus A. niger was able to produce organic acids that solubilized ions. This result indicates its potential to alter minerals contained in rock dust, with the ability to interact in different ways with the nutrients. A significant increase in the amount of K was found in the treatment with phonolite dust in the presence of the fungus. The strain CCT4355 of A. niger can solubilize minerals contained in these rocks dust

Acta Scientiarum Agricultural exploitation impact on the quality of natural waters in the trout-breeding region of the Mantiqueira ecological corridor

Agricultural exploitation impact on the quality of natural waters in the trout-breeding region of the Mantiqueira ecological corridor Acta Scientiarum. Biological Sciences, vol. 36, núm. 2, abril-junio, 2014, pp. 175-180 Universidade Estadual de Maringá ABSTRACT. Seasonal assessment of water quality was undertaken in an agricultural cattle-raising and trout-breeding region. Seventeen sites were sampled in ten municipalities close to the Papagaio and Ibitipoca State Parks in Minas Gerais, Brazil. Landsat 5 satellite images and Spotmap mosaic images with resolution of 2.5 m were employed to correlate classes of land use and topographic characteristics with the environmental contamination index of the water bodies at these sites. Results show a change in hydric classification of three sites evaluated. During the rainy season, sites 3, 7 and 17 were classified as class 3 according to CONAMA regulations, whereas the other sites were classified as class 2. During the dry season, sites 10 and 11 belonged to class 3 and the others to class 2. Literature and analysis of images and visits on the area showed that the principles of sustainable farming were not being followed in the region. Current research may be a tool for planning the preservation of natural resources. Results indicate there is a need for specific planning for fish farming and agriculture in the region for its sustainable economic exploitation. Keywords: water classification, water contamination, monitoring, geo-referencing. Impacto da exploração agropecuária na qualidade de águas naturais em região de truticultura no corredor ecológico da Mantiqueira RESUMO. Realizou-se a avaliação sazonal da qualidade da água, em região de truticultura e agropecuária, por amostragem, em 17 pontos, dez municípios, em torno dos parques estaduais do Papagaio e do Ibitipoca em Minas Gerais, Brasil. Usando imagens gratuitas Landsat 5 e imagens de mosaico Spotmap, resolução de 2,5 m, correlacionando as classes de uso da terra e características topográficas com o índice de contaminação ambiental dos corpos d'água nesses pontos. Os resultados mostram alteração da classificação hídrica de três dos pontos avaliados. Na época das chuvas, os pontos 3, 7 e 17 foram classificados como classe 3, de acordo com as normas do Conama (Conselho Nacional do Meio Ambiente), enquanto os outros pontos foram 2. Durante a estação seca, os pontos 10 e 11 eram de classe 3 e os outros como classe 2. A revisão de literatura, com a análise das imagens e visitas na área, mostrou que os princípios da agricultura sustentável não estão sendo seguidos na área. Este trabalho serve como ferramenta para o planejamento para preservação dos recursos naturais. Os resultados indicam que há a necessidade de um planejamento específico para a criação de peixes e agropecuária na região, permitindo assim sua exploração sustentável. Palavras-chave: classificação hídrica, contaminação da água, monitoramento, georreferenciamento