A review on effect of herbicides on soil biology and its functions

Abstract

There is a growing awareness among farmers about the importance of soil for sustaining crop production and providing beneficial ecosystem services. Over the last 2 decades, global herbicide use has increased as farmers have shifted to more sustainable conservation tillage practices and have adopted herbicide-tolerant crop cultivars. While the effects of increased herbicide use on soil biology are under scrutiny, there is a lack of a comprehensive review on this subject. Within this chapter, we detail the chemistry and application of major herbicide categories, and assess soil functions pertinent to crop production. Subsequently, we gather and analyse evidence regarding the impacts of herbicides on soil biota and activity. Overall, the majority of studies indicate that the effects of herbicide application on soil function are predominantly minor and/or temporary. Nonetheless, there are specific cases where findings consistently indicate effects that may substantially change soil function. These instances comprise disturbances to earthworm ecology in soils subjected to glyphosate and atrazine; hindrance of soil nitrogen cycling (encompassing biological nitrogen fixation, mineralization, and nitrification) by sulfonylurea herbicides in alkaline or low organic matter soils; and localized rises in disease due to the use of diverse herbicides. Challenges in extending these findings to broadacre farming encompass the absence of a uniform framework for evaluating herbicide risk to soil biology, the significance of herbicide impact magnitude compared to other soil management practices like tillage or crop rotation, the intricate nature of herbicide formulations and combinations, and the scarcity of long-term field studies.