Introducing Life Cycle Assessment in costs and benefits analysis of vegetation management in drainage canals of lowland agricultural landscapes

Nitrate pollution remains an unsolved issue worldwide, causing serious effects on water quality and eutrophication of freshwater and brackish water environments. Its economic costs are still underestimated. To reduce nitrogen excess, constructed wetlands are usually recognized as a solution but, in recent years, interest has been raised in the role of ditches and canals in nitrogen removal. In this study, we investigated the environmental and economical sustainability of nitrogen removal capacity, using as a model study a lowland agricultural sub-basin of the Po River (Northern Italy), where the role of aquatic vegetation and related microbial processes on the mitigation of nitrate pollution has been extensively studied. Based on the Life Cycle Assessment (LCA) approach and costs and benefits analysis (CBA), the effectiveness of two different scenarios of vegetation management, which differ for the timing of mowing, have been compared concerning the nitrogen removal via denitrification and other terms of environmental sustainability. The results highlighted that postponing the mowing to the end of the vegetative season would contribute to buffering up to 90% of the nitrogen load conveyed by the canal network during the irrigation period and would reduce by an order of magnitude the costs of eutrophication potential.