The practice of liming may influence the leaching of herbicides in soils, especially those with weak acid character, such as picloram. The study on leaching, preserving soil structure, is an important factor when one intends to understand the dynamics of herbicides and environmental impacts. Thus, the effect of liming on picloram leaching in a dystrophic Red Yellow Latosol under field conditions was studied using a bioindicator plant. The experiment was set up in a completely randomized design (CRD), in split-plot scheme, with factorial in the plot. The factors of the plot corresponded to two soil conditions (presence and absence of liming) and 5 picloram concentrations (0; 384; 768; 1152; 1536 g ha-1), and the factor of the subplot was 5 soil depths (0-8, 8-16, 16-24, 24-32 and 32-40 cm), with four replicates. Pipes were introduced into the soil and, in part of the treatments, limestone was applied superficially. After ninety days, the different doses of picloram were applied on the surface of each pipe and these pipes were withdrawn after an accumulated rainfall of 128 mm, to perform the bioassay using cucumber plants (Cucumis sativus). Evaluations of plant development (phytotoxicity and shoot biomass) were carried out 21 days after sowing. It was concluded that picloram showed high leaching rate under all studied conditions and liming increased picloram leaching at doses lower than 768 g ha-1.
Resumo -O 2,4-D e o picloram são moléculas muito utilizadas no controle de plantas daninhas em pastagens. Estudar o destino destas moléculas em solo da Amazônia é de extrema importância para avaliar o potencial de contaminação de águas subterrâneas. O presente trabalho teve como objetivo determinar a lixiviação de doses crescentes de 2,4-D + picloram em Latossolo Vermelho Amarelo Distrófico. Para isso, amostras desse solo foram usadas como substrato para preenchimento de tubos de PVC com 10 cm de diâmetro e 50 cm de comprimento. Os tratamentos constituíram da combinação de cinco doses 0,125; 0,25; 0,5 e 1,0% de um litro do produto comercial Tordon mais uma testemunha sem aplicação e seis profundidades de amostragem nas colunas (0; 8; 16; 24; 32 e 40 cm). Utilizou-se o pepino como espécie bioindicadora onde foram analisadas as seguintes variáveis: fitointoxicação, altura de plantas, comprimento radicular e área foliar. Realizou-se o experimento em delineamento inteiramente casualizado, com quatro repetições. Verificou-se que houve lixiviação do herbicida 2,4-D + picloram em Latossolo Vermelho-Amarelo Distrófico e que essa foi mais intensa com o aumento das doses dos herbicidas, chegando a ser lixiviado ao longo de toda a coluna estudada. Palavras-chave: auxinas, fitointoxicação, lixiviação, pepino, percolação Abstract -2,4-D and picloram are molecules much used in the control of weeds in pastures. Study the fate of these molecules in Amazonian soil is of extreme importance in assessing the potential for contamination of groundwater. The objective of the present work was to determine the leaching of increasing doses of 2,4-D + picloram herbicide in Dystrophic Yellow Red Latosol. For this, samples of this soil were used as substrate to fill PVC pipes with 10 cm in diameter and 50 cm in length. The treatments consisted of a combination of five doses 0.125; 0.25; 0.5 and 1.0% of one liter of the Tordon commercial product plus one control without application and six sampling depths in the columns (0; 8; 16; 24; 32 and 40 cm).The cucumber was used as bioindicator species where the following variables were analyzed: phytotoxification, plant height, root length and leaf area.
RESUMOO presente trabalho teve como objetivo determinar a lixiviação de doses crescentes do herbicida 2,4-D + picloram em LATOSSOLO VERMELHO AMARELO Distrófico utilizando a soja como espécie bioindicadora. Para isso, amostras desse solo foram usadas como substrato para preenchimento de tubos de PVC com 10 cm de diâmetro e 50 cm de comprimento. Os tratamentos compreenderam na combinação de cinco doses 0; 1; 0,5; 0,25; 0,125% de um litro do produto Tordon ® , e seis profundidades de amostragem nas colunas (0, 8, 16, 24, 32, 40 cm). Foram analisadas as seguintes variáveis: fitointoxicação, altura, comprimento radicular, área foliar e matéria seca. Realizou-se o experimento em delineamento inteiramente casualizado, com quatro repetições. Concluiu-se que há lixiviação do herbicida 2,4-D + picloram até 32 cm de profundidade em LATOSSOLO VERMELHO-AMARELO Distrófico, sendo que maiores concentrações do herbicida provocam maiores efeitos tóxicos em plantas de soja, mesmo em maiores profundidades. PALAVRAS-CHAVE: contaminação, fitointoxicação, movimentação de herbicida, Tordon. LEACHING OF THE HERBICIDE 2,4-D + PICLORAM LATOSOL RED-OXISOL DystrophicABSTRACT This study aimed to determine the leaching of increasing doses of the herbicide 2,4-D + picloram in Dystrophic Red Yellow Latosol using soy as bio-indicator species. For this, samples of this soil were used as a substrate for filling PVC tubes 10 cm in diameter and 50 cm long. The treatments consisted of the combination of five doses 0; 1; 0.5; 0.25; 0.125% Tordon ® one liter of product, six sampling depths in columns (0, 8, 16, 24, 32, 40 cm). The following variables were analyzed: phytotoxicity, height, root length, leaf area and dry matter. He carried out the experiment in a completely
The intensive use of herbicides has increased the possibility of environmental contamination and the accumulation of pesticide residues in soil and water. This work aimed to evaluate the leaching potential of 2,4-D and atrazine herbicides in red yellow Latosol with a clayey texture. The experimental design was entirely randomized, in factorial 5x3 (five doses of each herbicide for three soil depths). The doses used were 1.25, 2.50, 6.25 and 12.50 L ha-1 for the 2.4-D herbicide and 2.25, 4.50, 11.25 and 22.50 L ha-1 for the atrazine herbicide (plus absolute witnesses). The herbicides were applied in buried pvc tubes to the soil and after accumulated rainfall of 87 mm, cucumber was grown as a bio indicator plant. The plant phytotoxicity, plant height, dry mass accumulation and leaf area where the evaluations were performed at 21 days after the sowing of the cucumber were analyzed. The 2.4-D herbicide didn`t present significant difference between treatments for the plant phytotoxicity variable, however, there was difference between treatments for plant height and dry mass. For leaf area, the difference was observed only for soil depths. Atrazine herbicide also showed no difference between treatments for plant phytotoxicity, but there was a difference between treatments and soil depths for the other variables. Under the conditions evaluated, 2,4-D and atrazine herbicides can leach into clayey soil regardless of the dose used and can reach up to 30 cm depth.
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