Plant ‘barriers’ help boost streams
OPINION: Building barriers has been used for thousands of years to protect things.
This age-old practice is also useful in the modern context of protecting Waikato’s waterways.
Well-constructed and planted riparian margins beside water bodies form a barrier that can help to keep contaminants out.
These margins - strips of land next to the water-bodies – can filter out contaminants such as sediment, bacteria and nutrients from farm run-off, especially those contained in animal dung and urine, as well as agricultural chemicals.
Pathogens like giardia and cryptosporidium can cause waterborne diseases. Nitrates and phosphates can also create health disorders for people and stock, and contribute to algal growth.
Besides cleaner water generally, an important benefit of good riparian management is improved stock health because stock no longer get their drinking water from contaminated streams.
Winter weather can place increased strain on the banks of farm waterways, increasing the risk of stream bank erosion threatening paddocks and affecting water quality.
Some of our rivers, lakes and streams have eroding banks, silted beds, water weed infestation and reduced water quality, as a result of the way the land is used.
Land management practices – whether related to farming, forestry, roading or horticulture – can cause soil erosion and a buildup of contaminants into watercourses.
They include stock wading in water, poor cowshed effluent treatment, overgrazing, inappropriate fertiliser application, pugging and poor runoff control on cultivated land, and construction and use of roads and tracks which can all contribute to the contamination of water bodies. All of these practices can be managed to reduce the risk of generating contaminants.
A well-planted riparian margin creates a barrier between the farm system and the water body, helping to stabilise banks and filter out contaminants.
Shrubs and trees with extensive root systems, which tolerate moist soil conditions and frequent silt deposits, are ideal for stream bank erosion control.
Bala Tikkisetty is a sustainable agriculture advisor at Waikato Regional Council.
Waikato Regional Council staff doing riparian planting.