Efficacy and pH of glyphosate spray solutions after the addition of nitrogen fertilizers and the use of CO2-pressurized sprayer

Authors

  • Saul Jorge Pinto de Carvalho ESALQ / USP
  • Virginia Damin ESALQ / USP
  • Ana Carolina Ribeiro Dias ESALQ / USP
  • Gaspar Miura Yamasaki ESALQ / USP
  • Pedro Jacob Christoffoleti ESALQ / USP

DOI:

https://doi.org/10.1590/S1678-3921.pab2009.v44.1999

Keywords:

absorption, acidifi cation, herbicide spray, desiccation, ammonium sulfate, urea

Abstract

This work was developed with the objective of evaluating the efficacy and the pH of glyphosate spray solutions after the addition of nitrogen fertilizers and the use of CO2-pressurized sprayer. In field 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 CO2-pressurized sprayer. For all field condition evaluations, the lowest glyphosate rate had higher biological efficacy after the addition of ammonium sulfate (15 g L-1) to the spray solution. Urea (5 g L-1) promoted benefits only at the 28th-day evaluation. In laboratory, the increase of glyphosate concentration promoted gradual acidification of the spray solution, which stabilized at pH 4.5. Ammonium sulfate caused minor acidification of the herbicide solution, whereas urea did not change the pH. The use of CO2-pressurized sprayer had small effect on the solution's pH. Highest glyphosate efficacy identified after the addition of nitrogen fertilizers has little relation with changes on the solution's pH.

Author Biographies

Saul Jorge Pinto de Carvalho, ESALQ / USP

Engenheiro agrônomo, licenciado em ciências agrárias, mestre em agronomia pela ESALQ/USP. Atualmente é Dourando em Fitotecnia também na Esalq/USP, atuando na área de Plantas Daninhas e Herbicidologia.

Virginia Damin, ESALQ / USP

Engenheira Agrônoma (UFLA), mestre em Solos e Nutrição de Plantas (Esalq/USP). Atualmente, encontra-se em processo de conclusão de doutorado, também em Solos e Nutrição de Plantas - Esalq/USP.

Ana Carolina Ribeiro Dias, ESALQ / USP

Engenheira Agrônoma e Mestre em Fitotecnia - Esalq/USP. Atualmente é aluna de doutorado, também da Esalq/USP.

Gaspar Miura Yamasaki, ESALQ / USP

Graduando em Engenharia Agronômica - Esalq/USP. Estagiário da seção de Biologia e Manejo de Plantas Daninhas.

Pedro Jacob Christoffoleti, ESALQ / USP

Engenheiro Agrônomo, Ph.D., Professor Associado do Departamento de Produção Vegetal - Esalq/USP. Orientador de Doutorado em Fitotecnia.

Published

2010-11-18

How to Cite

Carvalho, S. J. P. de, Damin, V., Dias, A. C. R., Yamasaki, G. M., & Christoffoleti, P. J. (2010). Efficacy and pH of glyphosate spray solutions after the addition of nitrogen fertilizers and the use of CO2-pressurized sprayer. Pesquisa Agropecuaria Brasileira, 44(6), 569–575. https://doi.org/10.1590/S1678-3921.pab2009.v44.1999

Issue

Section

CROP SCIENCE