Reduce fertilizer or herbicide use: freshwater swamps
Overall effectiveness category No evidence found (no assessment)
Number of studies: 0
Background information and definitions
An excess of fertilizers and herbicides can have negative effects on vegetation. Herbicides can kill plants directly. An excess of nutrients, such as nitrogen and phosphorous, can alter the competitive balance leading to domination by single species (Tilman et al. 1999) or algal blooms (Smith et al. 2006). For many swamps, problems are related to chronic spillover of chemicals from agricultural or domestic land. Nutrient pollution is especially severe where a large proportion of the land is cultivated, e.g. in Europe, eastern North America and southeast China (Verhoeven et al. 2006). In some cases, e.g. rice paddies, excess chemical application could affect vegetation during the growing season and/or fallow periods.
Simply applying less fertilizer or herbicide to land/water near focal sites, or to agricultural wetlands, could reduce these problems. Ultimately, reduced application could be driven by legislation, financial incentives and/or education. Studies of organic farming – an agricultural system that minimizes the use of synthetic fertilizers and pesticides and relies on techniques such as crop rotation, compost and biological pest control (European Commission 2019) – are included within this action.
For this action, “reduction” includes stopping fertilizer or herbicide treatments altogether. Note that studies comparing areas that remain untreated to areas that become treated are not summarized as evidence for this action.
Related actions: Manage fertilizer or herbicide application, without reducing the total amount applied. In practice, that action and the current one will often be used simultaneously.
European Commission (2019) What is Organic Farming? Available at http://ec.europa.eu/agriculture/organic/organic-farming/what-is-organic-farming. Accessed 29 October 2019.
Smith V.H., Joye S.B. & Howarth R.W. (2006) Eutrophication of freshwater and marine ecosystems. Limnology and Oceanography, 51, 351–355.
Tilman E.A., Tilman D., Crawley M.J. & Johnston A.E. (1999) Biological weed control via nutrient competition: potassium limitation of dandelions. Ecological Applications, 9, 103–111.
Verhoeven J.T.A., Arheimer B., Yin C. & Hefting M.M. (2006) Regional and global concerns over wetlands and water quality. Trends in Ecology and Evolution, 21, 96–103.