Cadmium phytoavailability in soils and evaluation of extractant effectiveness using an isotope technique

Large areas of land are nowadays contaminated by heavy metals and, it is therefore, important to monitor their levels in soils. Vegetables act as transfer mechanisms of such contaminants from soils to higher levels in the food chain. In this study, we aimed to evaluate the effectiveness of chemical extractants by the L-value method for Cd phytoavailability using the 109Cd radionuclide. In a greenhouse experiment, rocket plants (Eruca sativa L.) were cultivated in pots with samples from Typic Hapludox and Typic Quartzipsamment soils. Cadmium concentrations ranging from 0 to 16 mg kg-1 were added to a 200 mL solution containing 148 kBq 109Cd. The available Cd in the soil was extracted by DTPA, Mehlich-1, Mehlich-3, and a mixture of organic acids (acetic, citric, lactic, and oxalic acids). Cd concentrations were determined by atomic absorption spectrophotometry, and 109Cd radionuclide activity was measured by low-level -counting. The dry matter yield was not influenced by Cd rates, but the Cd content and accumulation in shoots had a positive linear correlation. Generally, Cd was extracted in higher quantities by Mehlich-1 followed by DTPA, Mehlich-3, and organic acids. A linear correlation was found between the chemical extractants and Cd accumulation in shoots for both soils. According to the L Ratio, the extractants based on strong acids and chelating agents presented low efficiency regarding Cd phytoavailability. The organic acids, which presented values close to the L-value, may provide a promising method for evaluating environmental contaminants.

Cadmium phytoavailability in soils and evaluation of extractant effectiveness using an isotope technique

Large areas of land are nowadays contaminated by heavy metals and, it is therefore, important to monitor their levels in soils. Vegetables act as transfer mechanisms of such contaminants from soils to higher levels in the food chain. In this study, we aimed to evaluate the effectiveness of chemical extractants by the L-value method for Cd phytoavailability using the 109Cd radionuclide. In a greenhouse experiment, rocket plants (Eruca sativa L.) were cultivated in pots with samples from Typic Hapludox and Typic Quartzipsamment soils. Cadmium concentrations ranging from 0 to 16 mg kg-1 were added to a 200 mL solution containing 148 kBq 109Cd. The available Cd in the soil was extracted by DTPA, Mehlich-1, Mehlich-3, and a mixture of organic acids (acetic, citric, lactic, and oxalic acids). Cd concentrations were determined by atomic absorption spectrophotometry, and 109Cd radionuclide activity was measured by low-level -counting. The dry matter yield was not influenced by Cd rates, but the Cd content and accumulation in shoots had a positive linear correlation. Generally, Cd was extracted in higher quantities by Mehlich-1 followed by DTPA, Mehlich-3, and organic acids. A linear correlation was found between the chemical extractants and Cd accumulation in shoots for both soils. According to the L Ratio, the extractants based on strong acids and chelating agents presented low efficiency regarding Cd phytoavailability. The organic acids, which presented values close to the L-value, may provide a promising method for evaluating environmental contaminants.(AU)

Improving phosphorus availability from patos phosphate rock for Eucalyptus: a study with 32P radiotracer

Eucalyptus plantation in Brazil is generally set on low fertility soils, therefore phosphorus (P) fertilization is mandatory and increases the cost of plantation operation. Using species that more efficiently uptake phosphorus from less soluble sources is an interesting option. However, little is known about eucalyptus regarding its ability of using less soluble forms of phosphorus. The use of P by eucalyptus (E. urophylla, E. grandis, and E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis) was studied in greenhouse using a loamy-textured, hipodystrophic Typic Haplustox from the Cerrado region, and 32P isotopic method. The P sources tested were triple superphosphate (TSP), phosphate rock (PR) and the triple superphosphate mixed with PR (TSP+PR). The effectiveness of P sources in terms of increasing dry matter yield was TSP = (TSP + PR) > PR, and the P uptake followed the order (TSP + PR) > TSP > PR for both species plus the hybrid. The increase in P uptake from PR due to TSP influence was 217.3% for E. urophylla, 235.7% for E. grandis, and 28.7% for E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis, indicating an enhancement effect of TSP on the effectiveness of PR. The hybrid E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis was the most efficient genotype on P soil use and E. grandis most exigent in P fertilizer.

Como geralmente os solos usados para plantações de eucalipto no Brasil são de baixa fertilidade, a adubação fosfórica é indispensável, incrementando o custo da plantação. Espécies mais eficientes no uso de fósforo (P) de fontes pouco solúveis poderiam ser uma opção interessante. Porém, pouco se conhece ainda sobre o comportamento de eucalipto em relação à capacidade de usar fósforo de fontes com diferente solubilidade em água. O uso de P por eucalipto (E. urophylla, E. grandis, and E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis), foi estudado em experimento de casa de vegetação usando solo da Região de Cerrado, Latossolo Vermelho Amarelo hypodistrófico, e o método isotópico com 32P. As fontes de P usadas foram superfosfato triplo (SFT), rocha fosfórica (RF) e a mistura de superfosfato triplo com rocha fosfórica (SFT+RF). A eficácia das fontes de P em termos do aumento do rendimento de matéria seca seguiu a ordem SFT = (SFT + RF) > RF e de P absorvido a ordem (SFT + RF) > SFT > RF por ambas as espécies e o híbrido de eucalipto. O incremento na absorção de P de RF, influenciada pela mistura com SFT foi de 217,3% em E. urophylla, 235,7% em E. grandis e 28,7% em E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis, indicando o efeito benéfico do SFT sobre a efetividade da RF. O híbrido E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis foi o genótipo mais eficiente no uso de P do solo e E. grandis o mais exigente em P do fertilizante.

Improving phosphorus availability from patos phosphate rock for Eucalyptus: a study with 32P radiotracer

Eucalyptus plantation in Brazil is generally set on low fertility soils, therefore phosphorus (P) fertilization is mandatory and increases the cost of plantation operation. Using species that more efficiently uptake phosphorus from less soluble sources is an interesting option. However, little is known about eucalyptus regarding its ability of using less soluble forms of phosphorus. The use of P by eucalyptus (E. urophylla, E. grandis, and E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis) was studied in greenhouse using a loamy-textured, hipodystrophic Typic Haplustox from the Cerrado region, and 32P isotopic method. The P sources tested were triple superphosphate (TSP), phosphate rock (PR) and the triple superphosphate mixed with PR (TSP+PR). The effectiveness of P sources in terms of increasing dry matter yield was TSP = (TSP + PR) > PR, and the P uptake followed the order (TSP + PR) > TSP > PR for both species plus the hybrid. The increase in P uptake from PR due to TSP influence was 217.3% for E. urophylla, 235.7% for E. grandis, and 28.7% for E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis, indicating an enhancement effect of TSP on the effectiveness of PR. The hybrid E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis was the most efficient genotype on P soil use and E. grandis most exigent in P fertilizer.

Como geralmente os solos usados para plantações de eucalipto no Brasil são de baixa fertilidade, a adubação fosfórica é indispensável, incrementando o custo da plantação. Espécies mais eficientes no uso de fósforo (P) de fontes pouco solúveis poderiam ser uma opção interessante. Porém, pouco se conhece ainda sobre o comportamento de eucalipto em relação à capacidade de usar fósforo de fontes com diferente solubilidade em água. O uso de P por eucalipto (E. urophylla, E. grandis, and E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis), foi estudado em experimento de casa de vegetação usando solo da Região de Cerrado, Latossolo Vermelho Amarelo hypodistrófico, e o método isotópico com 32P. As fontes de P usadas foram superfosfato triplo (SFT), rocha fosfórica (RF) e a mistura de superfosfato triplo com rocha fosfórica (SFT+RF). A eficácia das fontes de P em termos do aumento do rendimento de matéria seca seguiu a ordem SFT = (SFT + RF) > RF e de P absorvido a ordem (SFT + RF) > SFT > RF por ambas as espécies e o híbrido de eucalipto. O incremento na absorção de P de RF, influenciada pela mistura com SFT foi de 217,3% em E. urophylla, 235,7% em E. grandis e 28,7% em E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis, indicando o efeito benéfico do SFT sobre a efetividade da RF. O híbrido E. urophylla FONT FACE=Symbol>´ /FONT> E. grandis foi o genótipo mais eficiente no uso de P do solo e E. grandis o mais exigente em P do fertilizante.

Utilização de fósforo do solo e do fertilizante por tomateiro

Phosphorus, despite its relatively low content in most crops is the most applied nutrient as mineral fertilizer and is an important fraction of the cost of agricultural production. Knowledge of the differences among plant varieties in relation to soil and fertilizer P uptake is fundamental for breeding improvement programs and management of phosphate fertilization. Differences in P uptake from soil and fertilizer (triple superphosphate), soil P availability through L and A values, and the physiologic, ecophysiologic and agronomic efficiencies of two commercial tomato (Lycopersicum esculentum Will) varieties, Santa Clara and Santa Cruz, were evaluated by the 32P technique. The experiment was carried out in a greenhouse, using two soils, a dystrophic Dark Red Latosol and an eutrophic Red Yellow Latosol, and two P fertilizer application rates (0 and 31.1 mg kg-1). Plant responses were markedly different in the two different soils. There was a clear increase in dry matter production, L value, and P uptake from the soil due to fertilizer application, but not in the A values. Differences in dry matter production, P concentration and physiologic, ecophysiologic and agronomic efficiency between varieties differed more for the eutrophic Red Yellow Latosol. There was no difference between the two varieties in relation to the uptake of soil and fertilizer P, L and A values.

O fósforo, embora seja o macronutriente em menor concentração na maioria das culturas, é o mais aplicado como fertilizante mineral, constituindo uma parcela significativa do custo de produção agrícola. O conhecimento das diferenças entre variedades de plantas em relação à absorção do fósforo do solo e do fertilizante torna-se de grande importância para programas de melhoramento e manejo da adubação fosfatada. Utilizando a técnica do traçador radioativo 32P, foram avaliadas as diferenças na absorção de fósforo proveniente do solo e do fertilizante (superfosfato triplo), na disponibilidade de P do solo pelos valores L e A e nas eficiências fisiológica, ecofisiológica e agronômica do nutriente pelas variedades comerciais de tomate (Licopersicum esculentum Will) Santa Clara e Santa Cruz. Conduziu-se um experimento em condições de casa de vegetação com dois solos (Latossolo Vermelho distrófico e Latossolo Vermelho-Amarelo eutrófico) e dois níveis de P (0 e 31,1 mg kg-1). A resposta das plantas foi diferente nos dois solos e em concordância com suas características. Houve aumentos significativos, em ambos os solos, na produção de matéria seca, no valor L e na absorção de P do solo devido à aplicação do fertilizante mineral, mas não no valor A. Diferenças entre variedades quanto à produção de matéria seca, concentração de fósforo, eficiência fisiológica, ecofisiológica e agronômica foram mais marcadas no solo Latossolo Vermelho-Amarelo eutrófico. Não houve diferenças entre as variedades na absorção de P do solo e do fertilizante, valores L e A.

Utilização de fósforo do solo e do fertilizante por tomateiro

Phosphorus, despite its relatively low content in most crops is the most applied nutrient as mineral fertilizer and is an important fraction of the cost of agricultural production. Knowledge of the differences among plant varieties in relation to soil and fertilizer P uptake is fundamental for breeding improvement programs and management of phosphate fertilization. Differences in P uptake from soil and fertilizer (triple superphosphate), soil P availability through L and A values, and the physiologic, ecophysiologic and agronomic efficiencies of two commercial tomato (Lycopersicum esculentum Will) varieties, Santa Clara and Santa Cruz, were evaluated by the 32P technique. The experiment was carried out in a greenhouse, using two soils, a dystrophic Dark Red Latosol and an eutrophic Red Yellow Latosol, and two P fertilizer application rates (0 and 31.1 mg kg-1). Plant responses were markedly different in the two different soils. There was a clear increase in dry matter production, L value, and P uptake from the soil due to fertilizer application, but not in the A values. Differences in dry matter production, P concentration and physiologic, ecophysiologic and agronomic efficiency between varieties differed more for the eutrophic Red Yellow Latosol. There was no difference between the two varieties in relation to the uptake of soil and fertilizer P, L and A values.

O fósforo, embora seja o macronutriente em menor concentração na maioria das culturas, é o mais aplicado como fertilizante mineral, constituindo uma parcela significativa do custo de produção agrícola. O conhecimento das diferenças entre variedades de plantas em relação à absorção do fósforo do solo e do fertilizante torna-se de grande importância para programas de melhoramento e manejo da adubação fosfatada. Utilizando a técnica do traçador radioativo 32P, foram avaliadas as diferenças na absorção de fósforo proveniente do solo e do fertilizante (superfosfato triplo), na disponibilidade de P do solo pelos valores L e A e nas eficiências fisiológica, ecofisiológica e agronômica do nutriente pelas variedades comerciais de tomate (Licopersicum esculentum Will) Santa Clara e Santa Cruz. Conduziu-se um experimento em condições de casa de vegetação com dois solos (Latossolo Vermelho distrófico e Latossolo Vermelho-Amarelo eutrófico) e dois níveis de P (0 e 31,1 mg kg-1). A resposta das plantas foi diferente nos dois solos e em concordância com suas características. Houve aumentos significativos, em ambos os solos, na produção de matéria seca, no valor L e na absorção de P do solo devido à aplicação do fertilizante mineral, mas não no valor A. Diferenças entre variedades quanto à produção de matéria seca, concentração de fósforo, eficiência fisiológica, ecofisiológica e agronômica foram mais marcadas no solo Latossolo Vermelho-Amarelo eutrófico. Não houve diferenças entre as variedades na absorção de P do solo e do fertilizante, valores L e A.