Degradation of pesticides in biobeds
Pesticides are used to protect crops from unwanted pests thereby increasing food quality and quantity. However, one side-effect of using pesticides is their ability to pollute surface and groundwaters through diffuse (non-localized) or localized (point) sources. Biobeds were introduced in Sweden in 1993 as a means to protect the environment from point source pollution by pesticides arising from farm activities such as filling of sprayers and sprayer rinsate. A biobed is a hole in the ground into which a mixture of straw, compost and topsoil (2:1:1 by volume) is added and cover with a grass layer. The biobed mix creates a favourable environment for containment and microbial degradation of applied pesticides. The objective of this study is to investigate the relationship between active ingredient breakdown and carbon dioxide emission in both topsoil and biobed mix after pesticide application. Results indicate a five-fold reduction in the half-life of 2,4-D in the biobed mix compared to topsoil. Rapid degradation of some sulphonylurea herbicides occurred in the biobed mix despite their known persistence in soil. There was a correlation between active ingredient breakdown and carbon dioxide emission.
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