Modify crop farming practices in watershed to reduce pollution: brackish/salt marshes
Overall effectiveness category No evidence found (no assessment)
Number of studies: 0
Background information and definitions
Crop farming in watersheds can lead to pollution of focal marshes. Soil and nutrients can run off arable land and accumulate in wetlands, affecting the plant community composition, plant diversity and distribution of plant species (Verhoeven et al. 2006; Bromberg Gedan et al. 2009). Extreme excesses can cause algal blooms or even fill in wetlands (Gleason & Euliss Jr. 1998). Crop farming can also contribute to salinization and acidification, by raising the local water table and bringing salts to the surface. This can occur through (a) excess irrigation or (b) replacing native, perennial deep-rooted vegetation with shallow-rooted, temporary crops that don’t take up as much water (NSW Government 2019). Alternatively, runoff of excess fresh irrigation water can pollute brackish/saline sites (Zedler 1983).
This action includes a range of specific management techniques, other than changes in fertilizer or herbicide use that are considered as separate actions, that might reduce pollution from arable farming in wetland catchments. For example, ploughing or harrowing parallel to slopes avoids creating channels that carry soil and nutrients. Terraces may help to retain soil and nutrients. Minimizing the number/duration of fallow periods, and planting cover crops during them, could minimize sediment/chemical runoff and infiltration of water. Water table rise could also be reduced by tailoring irrigation to the needs of crops, increasing irrigation efficiency (e.g. replacing leaking pipes) and installing systems to retain excess irrigation water on site (NSW Government 2019).
Bromberg Gedan K., Silliman B.R. & Bertness M.D. (2009) Centuries of human-driven change in salt marsh ecosystems. Annual Review of Marine Science, 1, 117–141.
Gleason R.A. & Euliss N.H. Jr. (1998) Sedimentation of prairie wetlands. Great Plains Research, 8, 97–112.
NSW Government (2019) Type of Salinity and their Prevention. Available at https://www.environment.nsw.gov.au/topics/land-and-soil/soil-degradation/salinity/type-of-salinity-and-their-prevention. Accessed 30 December 2020.
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.
Zedler J.B. (1983) Freshwater inputs in normally hypersaline marshes. Estuaries, 6, 346–355.