Microcalorimetry of the degradation of the herbicide 2,4-D via the microbial population on a typical Brazilian red Latosol soil

The herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) was applied to a typical Brazilian red Latosol soil. The thermal effects evolved by 2,4-D degradation were followed in a series of microcalorimetric experiments. The power–time curves were recorded for increasing doses of herbicide, varying from 0 to 6.67 mg g−1 under a 34.8% controlled humidity. The herbicide was used as a food source by soil microbes, the degradation causing the thermal effect. The thermal effect increases to 2.67 mg g−1. Above this concentration, a decrease of the thermal effect was observed due to toxicity of 2,4-D to the microbes.