Lixiviação e absorção de Pb pelo feijão-de-porco assistido pela aplicação de EDTA no solo

Lead (Pb) is one of the main soil contaminants. It is also of difficult phytoremediation due to its low solubility and high retention on soil particles. EDTA application to soil is a strategy to increase heavy metal phytoextraction, but such chelants usually cause phytotoxicity and metal leaching side effects. Therefore, these research work objectives were to evaluate the effects of single (0.5 g kg-1) and split (0.25 + 0.25 g kg-1) EDTA application on Pb uptake by jack beans (Canavalia ensiformis L.) as well as on Pb vertical movement in a Pb contaminated soil material. Two sets of experiments were carried out under greenhouse conditions: in the first one, plants were grown in 3L-pots filled with a Pb-contaminated soil to evaluate Pb uptake by plants; for the second experiment, PVC-columns (42 cm height) were used to evaluate soil Pb leaching: the upper half-column (20 cm) was filled up with Pb-contaminated soil (1800 mg kg-1) whereas the lower half-column (20 cm) was filled with clean soil. Ten 60 mm-rainfalls with a duration of five hours were simulated by dropping distilled water on the top of columns, and leachates were collected for chemical analysis. Plants did not show any visual Pb toxicity symptoms or reduction in dry matter yield. Nevertheless, Pb uptake by jack beans regarded as total plant Pb accumulation was higher in EDTA-treated plants. Vertical Pb movement was observed mostly for the single EDTA application. EDTA addition to the soil favor Pb-phytoextraction by jack beans and the split EDTA application decrease the metal leaching, indicating less risk of environmental contamination.O chumbo (Pb) é um dos principais contaminantes de solo. Os processos de remediação são dificultados devido à alta retenção do elemento às partículas do solo. A utilização do EDTA para aumentar a fitoextração dos metais do solo tem apresentado bons resultados. Contudo, os quelantes podem causar efeitos indesejáveis como a fitotoxidez e a lixiviação do metal. Nesse sentido, avaliou-se o efeito da aplicação única (0,5 g kg-1) e parcelada de EDTA (0,25 + 0,25 g kg-1) na absorção de Pb pelas plantas de feijão-de-porco (Canavalia ensiformis L.) e na movimentação vertical de Pb em solo contaminado, sob condições de casa de vegetação. Em um experimento, as plantas foram crescidas em vasos contendo 3 L de solo contaminado por Pb. No outro, utilizaram-se colunas de PVC com 42 cm de altura, preenchendo-se os primeiros 20 cm com solo contaminado com 1800 mg kg-1de Pb, seguido de outros 20 cm, com amostra de solo não contaminado. Nesse experimento, foram feitas dez lixiviações com água em volume equivalente a uma chuva de 60 mm cada. As plantas não apresentaram sintomas visuais de toxicidade de Pb, nem diferença na produção de massa seca do feijão em função dos tratamentos aplicados. No entanto, a absorção de Pb foi superior para as plantas que receberam EDTA. Houve movimentação vertical de Pb no solo, principalmente devido à aplicação única de EDTA. A adição de EDTA ao solo auxilia a fitoextração de Pb por plantas de feijão-de-porco e que o parcelamento do EDTA diminui a lixiviação do metal, mostrando se menos agressivo ao ambiente

Biosolids Application on Banana Production: Soil Chemical Properties and Plant Nutrition

Biosolids are relatively rich in N, P, and S and could be used to substitute mineral fertilization for banana crop. A field experiment was carried out in a Yellow Oxisol to investigate the effects of biosolids application on soil chemical properties and on banana leaf's nutrient concentration during the first cropping cycle. Soil analysis (pH, organic matter, resin P, exchangeable Ca and K, available B, DTPA-extracted micronutrients, and heavy metals) and index-leaf analysis (B, Cu, Fe, Mn, Zn, Cd, Cr, Ni, and Pb) were evaluated. Biosolids can completely substitute mineral N and P fertilizer to banana growth. Soil exchangeable K and leaf-K concentration must be monitored in order to avoid K deficiency in banana plants. No risk of heavy metal (Cr, Ni, Pb, and Cd) concentration increase in the index leaf was observed when biosolids were applied at the recommended N rate

Fertility Evaluation of Limed Brazilian Soil Polluted with Scrap Metal Residue

The aim of this work was to characterize the main inorganic contaminants and evaluate the effect of lime addition, combined with soil dilution with uncontaminated soil, as a strategy for mitigation of these contaminants present in a soil polluted with auto scrap. The experiment was performed in a greenhouse at Campinas (São Paulo State, Brazil) in plastic pots (3 dm−3). Five soil mixtures, obtained by mixing an uncontaminated soil sample with contaminated soil (0, 25, 50, 75, and 100% contaminated soil), were evaluated for soil fertility, availability of inorganic contaminants, and corn development. In addition to the expected changes in soil chemistry due to the addition of lime, only the availability of Fe and Mn in the soil mixtures was affected, while the available contents of Cu, Zn, Cd, Cr, Ni, and Pb increased to some extent in the soil mixtures with higher proportion of contaminated soil. Liming of 10 t ha−1 followed by soil dilution at any proportion studied was not successful for mitigation of the inorganic contaminants to a desired level of soil fertility, as demonstrated by the available amounts extracted by the DTPA method (Zn, Pb, Cu, Ni, Cr, Cd) and hot water (B) still present in the soil. This fact was also proved by the phytotoxicity observed and caused by high amounts of B and Zn accumulating in the plant tissue

Mineralization of carbon and nitrogen in soil after successive applications of sewage sludge

O objetivo deste trabalho foi avaliar a dinâmica de mineralização do C e a capacidade do solo em fornecer N após sucessivas aplicações de lodo de esgoto, além de determinar a relação destas com a taxa de mineralização do lodo previamente aplicado. A área experimental recebeu, por sete anos, os seguintes tratamentos: 80 kg ha-1 por ano de N mineral (L0); e 10 ou 20 Mg ha-1 por ano de lodo (L1 e L2, respectivamente). Amostras de solo (0–20 cm) foram retiradas um ano após a última aplicação dos tratamentos. As amostras receberam doses de lodo correspondentes a 0, 120 e 240 kg  ha-1 de N e foram incubadas em laboratório por mais de 100 dias, tendo-se determinado o C‑CO2 liberado e o teor de N inorgânico no solo. A mineralização do C e do N foi mais influenciada pelo uso prévio do lodo do que pelas doses incubadas. A taxa de mineralização do nitrogênio (TMN) diminuiu de 16%, em L0, para 11%, em L1, e 8% em L2. No entanto, essa redução não resultou em menor disponibilidade de N no sistema, pois houve incremento do N potencialmente mineralizável (N0) em L1 e L2. Assim, a TMN não é um parâmetro adequado para cálculo da dose de lodo a ser aplicada em áreas previamente tratadas com o resíduo, pois subestima a capacidade do sistema em fornecer N. Neste caso, deve-se considerar o uso do N0.The objective of this work was to evaluate the dynamics of carbon mineralization and the soil capacity in providing nitrogen after successive applications of sewage sludge, as well as to determine their relation with the mineralization rate of the sludge previously applied. The experimental area received for seven years the following treatments: 80 kg ha‑1per year of mineral N (L0); and 10 or 20 Mg ha‑1 per year of sewage sludge (L1 and L2, respectively). Soil samples (0–20 cm) were taken one year after the last application of the treatments. Samples received sewage sludge doses corresponding to 0, 120, and 240 kg ha‑1 of N and were incubated in laboratory for more than 100 days, with determination of C‑CO2 emission and inorganic soil N content. The mineralization of C and N was more influenced by the previous use of sludge than by the incubated doses. The nitrogen mineralization rate (NMR) reduced from 16%, on L0, to 11% on L1 and 8% on L2. However, this reduction did not result in lower N availability on the system, since there was an increase of the potentially mineralizable nitrogen (N0) in L1 and L2. Therefore, the NMR is not an adequate parameter for calculating the sewage sludge dose to be applied on areas previously treated with the residue, since it underestimates the system capacity of providing N. In this case, the use of N0 should be considered

NO2 - and NO3 - leaching and solubilization of Al in variable charge soils treated with sewage sludge

The use of sewage sludge (SS) for agricultural purposes provides macronutrients and micronutrients and increases the soil organic matter. This study was conducted after 5 years of agricultural sludge application to a variable charge soil (clay loam-textured dark red dystroferric oxisol) in an experimental field at the Brazilian Federal Agriculture Research Institute in JaguariA(0)na, So Paulo. The mineralization of SS organic matter forms sulfate (SO4 (2-)) and ammonium (NH4 (+)) or ammonia (NH3). Subsequently, nitrification of NH4 (+) or NH3 occurs, resulting in the formation of nitrite (NO2 (-)) and NO3 (-) which release H+ and increases the redox potential of the solution. In studied area, the SS organic matter decomposition favored the anion exclusion, which led to SO4 (2-), NO2 (-) and NO3 (-) leaching along the profile. At 2 m, the soil solution showed pH and Eh values of 4.2 and 600 mV, respectively. In addition, the highest soil NO2 (-) (27 mg/L), NO3 (-) (1220 mg/L) and Al (20 mg/L) concentrations were observed at 2 m. The low pH and high Eh at 2 m potentially resulted from the oxidation of leached NO2 (-). Furthermore, the H+ released in solution due to nitrification was partially consumed during the solubilization of soil Al compounds, such as kaolinite and amorphous Al oxide. Geochemical modeling (GM) indicated that Al3+ in solution results from the solubilization of kaolinite and amorphous Al oxide. GM also highlights the importance of soil oxide protonation in buffering the soil solution acidity and in controlling the solubility of Al compounds and free Al in solution.The use of sewage sludge (SS) for agricultural purposes provides macronutrients and micronutrients and increases the soil organic matter. This study was conducted after 5 years of agricultural sludge application to a variable charge soil (clay loam-textured dark red dystroferric oxisol) in an experimental field at the Brazilian Federal Agriculture Research Institute in JaguariA(0)na, So Paulo. The mineralization of SS organic matter forms sulfate (SO4 (2-)) and ammonium (NH4 (+)) or ammonia (NH3). Subsequently, nitrification of NH4 (+) or NH3 occurs, resulting in the formation of nitrite (NO2 (-)) and NO3 (-) which release H+ and increases the redox potential of the solution. In studied area, the SS organic matter decomposition favored the anion exclusion, which led to SO4 (2-), NO2 (-) and NO3 (-) leaching along the profile. At 2 m, the soil solution showed pH and Eh values of 4.2 and 600 mV, respectively. In addition, the highest soil NO2 (-) (27 mg/L), NO3 (-) (1220 mg/L) and Al (20 mg/L) concentrations were observed at 2 m. The low pH and high Eh at 2 m potentially resulted from the oxidation of leached NO2 (-). Furthermore, the H+ released in solution due to nitrification was partially consumed during the solubilization of soil Al compounds, such as kaolinite and amorphous Al oxide. Geochemical modeling (GM) indicated that Al3+ in solution results from the solubilization of kaolinite and amorphous Al oxide. GM also highlights the importance of soil oxide protonation in buffering the soil solution acidity and in controlling the solubility of Al compounds and free Al in solution74646254638FAPESP [02/09667-3, 02/12671-2, 03/10949-6