Behavior aminocyclopyrachlor in function of the addition of organic material in soil

Author(s)

Vanessa Takeshita

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Centro de Energia Nuclear na Agricultura (CENA/STB)
• Defense date: 2019-08-06

Examining board members

Valdemar Luiz Tornisielo; Robson Rólland Monticelli Barizon; Leonardo Fernandes Fraceto

• Advisor: Valdemar Luiz Tornisielo

Abstract

The organic matter is one of the most influential components in the behavior of herbicides applied via soil, being able to alter the dynamics of these compounds in the environment. The objective of this study was to evaluate the effect of altered soils with sugarcane straw, filter cake and vinasse on sorption-desorption, leaching, mineralization and degradation of aminocyclopyrachlor in soil. Sorption-desorption was verified by the batch equilibrium method, with organic materials aged in the soil (0, 15, 30 and 60 days). The leaching was carried out in glass columns (200 mm in 48 hours) with the herbicide concentrations measured in the soil profile (0-0.30 m) and in the leachate. Biodegradation was conducted for 112 days in biometric vials. The sorption of the herbicide was low for all treatments (Kd = 0.17-0.41 L kg-1), with desorption of a large part of the herbicide applied. Less than 2 % of the herbicide was retained in straw and filter cake, with greater distribution in the soil profile. Vinasse increased herbicide leaching (71 %) in relation to other materials and soil without change (~ 50 %). Mineralization of aminocyclopyrachlor was low (<45 % in 112 days), with ~ 30 % formation of bound residue without observation of metabolite formation throughout the study. The half-life (DT50) in the soil without addition of organic material was 187 days, with addition of organic materials reached 247-277 days and 90 % degradation was estimated at 600-900 days for all treatments. The presence of organic materials in the soil promoted greater availability of aminocyclopyrachlor in solution, mainly for the leaching, besides having its persistence increased in the environment. The persistence of the herbicide in the environment favors the longer control of weeds, especially when there is greater availability in the soil, but in the management of this herbicide in a sugar cane system, in which there is a great contribution of organic matter in the soil, may favor the contamination of groundwater (AU)

• FAPESP's process: 17/20402-7 - Behavior of aminocyclopyrachlor in the function of the addition of organic materials in soil
• Grantee: Vanessa Takeshita
• Support Opportunities: Scholarships in Brazil - Master