The purpose of this study was to evaluate decomposition due to mechanical control of three submerged aquatic weed species incorporated into soil at hydroelectric reservoirs. The study was carried out in a greenhouse at the Weed Science Center (NUPAM), FCA/UNESP-Botucatu. Evaluation was performed in vases containing 14 kg of soil, with three 50 and 100 t plant fresh matter ha-1 incorporations, under two soil conditions: dry and wet. By simulating the biomass harvested and incorporated into soil, degradation of the three aquatic macrophyte weed species could be verified through released CO2. To quantify released CO2, a flask with NaOH solution was placed into each vase, sealed and incubated for 24 hours, followed by HCl titration. For data adjustment and interpolation, Mitscherlich model modified was used. CO2 released into wet soil was 1,294 and 1,582 kg ha-1, being 6.2 and 5.6 times than that released into dry soil, for 50 and 100 t FM ha-1, respectively. It was observed that about 55% of the released CO2 occurred at day 30. It can be concluded that dry soil is the best condition for biomass discard and incorporation. However, degradation is accelerated under irrigation.
mechanical control; discard; aquatic macrophytes
