Eficácia e pH de caldas de glifosato após a adição de fertilizantes nitrogenados e utilização de pulverizador pressurizado por CO 2
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Data
2009-06
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Resumo
This work was developed with the objective of evaluating the effi cacy and the pH of glyphosate spray
solutions after the addition of nitrogen fertilizers and the use of CO 2 -pressurized sprayer. In fi eld conditions,
two rates of glyphosate (360 and 720 g ha -1 ) were applied either alone or combined with two concentrations
of urea (2.5 and 5.0 g L -1 ) or ammonium sulfate (7.5 and 15.0 g L -1 ). In laboratory, the pH of the glyphosate
solutions was measured after using different concentrations of the product and nitrogen fertilizers and after
using a CO 2 -pressurized sprayer. For all fi eld condition evaluations, the lowest glyphosate rate had higher
biological effi cacy after the addition of ammonium sulfate (15 g L -1 ) to the spray solution. Urea (5 g L -1 )
promoted benefi ts only at the 28 th -day evaluation. In laboratory, the increase of glyphosate concentration
promoted gradual acidifi cation of the spray solution, which stabilized at pH 4.5. Ammonium sulfate caused
minor acidifi cation of the herbicide solution, whereas urea did not change the pH. The use of CO 2 -pressurized
sprayer had small effect on the solution’s pH. Highest glyphosate effi cacy identifi ed after the addition of
nitrogen fertilizers has little relation with changes on the solution’s pH.
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Palavras-chave
Absorção, Sulfato de amônio, Acidificação, Calda herbicida, Dessecação, Ureia, Absorption, Ammonium sulfate, Acidification, Herbicide spray, Urea, Desiccation
Citação
CARVALHO, Saul Jorge Pinto de; DAMIN, Virginia; DIAS, Ana Carolina Ribeiro; YAMASAKI, Gaspar Miura; CHRISTOFFOLETI, Pedro Jacob. Eficácia e pH de caldas de glifosato após a adição de fertilizantes nitrogenados e utilização de pulverizador pressurizado por CO2. Pesquisa Agropecuária Brasileira, Brasília, v. 44, n. 6, p. 569-575, jun. 2009.