Interaction of Herbicides with Azolla and Soil Microbes

Application of herbicide influences the soil biological activity. The effect of use of pre-emergence herbicides viz., anilophos, butachlor and thiobencarb 0.3, 1.0 and 1.0 kg/ha respectively on soil bacteria, fungi and actinomycetes were investigated in 5 cm surface soil at 0, 10, 20, 30, 60 and 90 days after herbicides application. These were inhibitory to soil microflora. The effect of herbicidal use on Azolla microphylla Kaulfuss raised as dual crop with paddy by inoculating 1 t/ha on 10 and 15 days after transplanting (DAT) was also investigated. Application of A. microphylla 12 days after herbicides application (15 DAT) was found to be safe when compared to 7 days (10 DAT) after herbicides application. Under in vitro condition;, all these herbicides were inhibitory to A. microphylla at 10 ppm concentration and above.