Transporte e sorção do imazapic em solos cultivados com cana-de-açúcar

Abstract

Herbicides compose an important part of pesticides, comprising around 45% of all pesticides used in agriculture. Herbicides can be used pre or post-emergence in the control of weeds in various crops, particularly in crops like soybean, corn and sugarcane. The culture of sugarcane is produced mostly in the Southeast of Brazil, covering about 85% of production, while the Northeast comprises around 13% of production in the country. In Pernambuco, the regions of the south and north woods are the cane producers in the state, the climatic conditions (hot and humid) favor its cultivation. The Imazapic herbicide is used in direct contact with the ground as a pre-emergent. The work was to evaluate the interaction of Imazapic herbicide in soil using miscible displacement tests in soil columns, since the soil and water with pesticides recurs due to high mobility, creating major environmental concern. Studies were carried out in soil columns with a YELLOW ultisol Dystrophic (AAd) and Oxisol dystrophic (LVAd) of the north woods of Pernambuco state cultivated with sugarcane. The evaluation of soil mobility was based on different physical, chemical and mineralogical for AAd and LVAd. Imazapic concentration was determined by high-performance liquid chromatography (HPLC). A review of the mechanisms involved in the transport and determination of hydrodispersive parameters of Bromide Potassium breakthrough curves (KBr) fitted well the CDE model (Convection - Dispersion). The breakthrough curves for the Imazapic were adjusted using the two sites nonequilibrium model (CDE-2S) through the CXTFIT 2.0 program. The partition coefficient Kd for LVAd averaged 0.18 kg L-1 while for the AAd averaged 0.084 kg L-1, with average values of GUS index 6.2 and 6.8 respectively, confirming high leaching potential of the Imazapic molecule in the soils. The greater interaction of Imazapic molecule occurred with the LVAd due to soil physicochemical factors as higher clay content (30%) and higher concentrations of Fed and Feo, thus slowing the potential leaching of the herbicide in this class of soil and consequently the contamination of water resources implications.