Riparian planting has many benefits on a farm, from reducing sediment entering waterways to making it easier to manage stock. Elaine Fisher reports.
Fenced and planted riparian zones are a valuable asset for a dairy farm, and summer is a good time to start planning your next riparian or wetland planting project, says Jackson Efford, principal adviser land and water for the Bay of Plenty Regional Council.
DairyNZ’s step-by-step guide to successful riparian planting is a great starting point for those considering undertaking a planting project, and project advice and support may also be available from your local regional council.
“It’s important to not only think about fencing, but also how riparian areas will be maintained and enhanced once fencing is complete. In many cases, native planting is the preferred choice,” says Jackson. Planted riparian areas have many benefits. “Plants stabilise banks and can function like a sieve, helping to filter out sediment and nutrients that leave farmland in runoff before entering waterways, and also provide valuable habitats for native animals.
“Less sediment means less cost for drain clearing and less risk of flooding. Riparian zones reduce nutrients getting into waterways, decrease weed growth, improve biodiversity and water quality, and provide a better environment for swimming and fishing.
“Well managed riparian zones will protect stock from getting stuck or drowning in waterways, provide more shade, reduce heat stress, and make it easier to manage stock. Riparian plants also stabilise banks with their roots, limiting the loss of land through erosion.”
Water quality is coming under increasing public and government scrutiny and the dairy industry’s response includes the Sustainable Dairying: Water Accord developed in 2013, which was a five-year commitment to manage land in a way that contributes to achieving water quality desired by New Zealanders.
Some achievements through the accord include:
- Fencing off dairy cattle from 24,249km (98.3%) of significant dairy accord waterways
- Installing bridges and culverts on 100% of stock crossing points dairy cows use
- Assessing 100% of accord farms for effluent management practices.
Riparian zones are strips of land beside drains, streams, rivers and lakes. They include areas on the farm where the soils are wettest, such as wetlands, springs or seeps, and gullies.
“Having a plan for riparian planting is the key to getting value for money and doing it right the first time,” says Jackson.
“Your riparian plan should cover the three steps of fencing, planting and maintaining your riparian zones. Use your farm knowledge to form your plan.”
To avoid losing plants in floods, determine how your waterway behaves in full flow. This will help decide where to place fences and what to plant.
Identify areas on your farm where runoff or erosion occur most frequently and that have the greatest effect on water quality. This includes seeps, springs, gullies, eroding banks, boggy areas and wet soils, which should be part of the fenced area and prioritised for planting.
You should also decide what is manageable. Fencing can be completed reasonably quickly, whereas planting and follow-up maintenance takes longer. During planning, set a realistic timeframe and budget for planting. For example, by planting 25% of the area per year, your riparian zones will be complete in four years.
“All waterway fencing needs to be permanent to guarantee stock exclusion. That’s because livestock trample and graze plants. They also damage banks and defecate in water, adding sediment, nutrients and bacteria that reduce water quality.”
Mapping your waterways and creating a fencing plan is recommended. Work out fence lines and crossing points and choose a suitable fencing setback distance. The aim of the fencing setback distance is to slow runoff enough to ensure as much bacteria, nutrients and sediment as possible are filtered out before they enter a waterway. A setback distance for a healthy riparian zone should vary onfarm to reflect different soil types, slopes, and water flow, but must be a minimum of 3m for new fences to meet the new national Resource Management Act stock exclusion regulations.
“A wider setback is needed on steeper paddocks, longer paddocks and heavier soils, because these all generate fast-flowing runoff. On flat to undulating land, relatively small zones of 3–5m are still capable of reducing nutrients, sediment and bacteria entering waterways.”
Jackson recommends keeping in mind what you want to achieve by planting the zones. “If you want to create shade for your stream to reduce weed growth and keep streams cool, you may need wider zones to allow more space for the trees. If you want to filter nutrients, sediment and bacteria from runoff, then smaller zones (3–5m) with shrubs and grasses will still be effective.”
Consent for certain types of fencing or planting may be required. Check with the local council to see if the farm is within a flood control or land drainage scheme area before starting any work.
“The next step is to decide what to plant, where, and at what spacing. There can be up to three zones of plant types on a healthy riparian zone. Planting your upper and lower banks will improve water quality more than using grass strips alone.”
Maintaining access to drains is important, so only plant up one side near drains, preferably the north bank to provide the stream with shade in summer. Avoid planting deep-rooted species (upper bank plants) over tile drains.
Keeping on top of weeds and pests is crucial in the first five years for a healthy riparian zone to become established. Combining protective and active maintenance methods is recommended as the most effective maintenance option.
“Grass strips do a great job of filtering runoff. Avoid the temptation to let livestock graze your margins, even if it is just rank grass. If you need to, brush-cut your grass filter strips – don’t spray them.”
Regional councils have rules about what can and cannot be done near or to waterways. For example, activities you may need consent for around riparian zones include:
- Construction of bridges, culverts, fords, tracks and raceways
- Activities that disturb the bed of a river or lake, including the removal or deposition of sediment
- Clearing vegetation in, on, or under the bed of a river or lake. This may include removing vegetation, rocks, gravel, sediment or other obstructions from a waterway
- Drainage of a wetland or the creation or deepening of drains close to a wetland
- Introducing or planting pest plants.
For more information on riparian planting and suitable plants, visit dairynz.co.nz/riparian and use the riparian planter tool: riparian-planner.dairynz.co.nz or contact your regional council.
