Modelagem de lixiviação do herbicida picloram atraves de lisimetro de drenagem sob vegetação de Brachiaria decumbens / Modeling of picloram herbicide leaching in a lysimeter under Brachiaria decumbens vegetation

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

Picloram is one of the most used herbicides in the control of weeds in pastures areas, especially the ones of difficult eradication. Many are the stories of wells and springs contamination with herbicides residues as a result of its leaching in grounds. Due to the lack of knowledge and available data on the destination of the picloram in brazilian grounds, researches in these soil conditions and climate become necessary to evaluate the potential of underground water contamination with residues of such herbicide. With the objective of evaluating the vertical movement of the picloram herbicide in field conditions and by simulation using a simulator, a test was made to verify the hypothesis that the use of the picloram herbicide, in controlled environment and through results of a mathematical simulator, is absorbed to the clay and ground with high amounts of organic substance, presenting low vertical mobility and low potential of underground water contamination. The work was lead in the Experimental Field of the College of Agricultural Engineering of UNICAMP, having used draining modified lysimeter 2 m diameter per 3 m depth, with 10 vertical points, through which water samples of rain had been collected. The samples were collected 1 day after rains in the period from October 2006 to March 2007 and submitted to Gas Chromatographic Analysis with detection by means of mass espectrometro - CGMSD. Because there was no information about values (sorption coefficient) and (half-life) for the Picloram herbiced under clay soils, it was necessary to obtain these, under laboratory conditions. For the simulations a MACRO 5.1 simulator was used. The data found through the analyses of the samples collected in field and the simulations in MACRO 5.1 indicated a decreasing presence of the picloram herbicide during this time, confirming the hypothesis of low vertical mobility of this herbicide, in a decreasing curve, and indicating, for this ground, low potential of contamination of underground waters. The simulator showed a Picloram herbicide movement in the soil profile, but in an underestimated way.

ASSUNTO(S)

pesticides lisimetro simulation environmental contamination simulação por computador picloram pesticidas solos - lixiviação

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