Low planting lifts water quality

Long dense grass, flax, sedges and rushes serve as a filter to help remove sediment, bacteria and nutrients (mostly phosphorus) from surface runoff. The planting shades narrow waterways (less than 2m) and improves the habitat for fish.

There are a number of locations where low planting will be most effective at improving water quality, such as along drains and small lowland streams that feed into main rivers; areas with significant runoff; and beside waterways strip grazed in autumn and winter.

Other ideal locations are beside vegetated drains in areas with poor soil drainage or pugging and moderate slopes, and where paddocks are cultivated.

In general, the steeper and longer the slope feeding into the waterway, or the more poorly drained the soil, the wider the planted area needs to be.

For gently rolling land, a margin width of 1-3m per 100m of slope feeding into the waterway is ideal. In areas with steeper slopes or poorly draining soils, a grassy margin of 10-15m per 100m of adjacent slope is recommended.
Getting plants in the ground
Here are some simple reminders to help get plants off to a good start:

Plant on an overcast, wet or windless day (if you can)

Handle plants carefully to avoid root damage

Set plants out to check for correct spacing

Dig a good size hole and loosen the soil

Set the plant in the hole and fill three quarters full. Give the plant a gentle lift to set the roots in a natural position and continue filling with soil, firming as you go

Stake plants to help find them again at weeding time. 

Weed growth (especially gorse, broom and blackberry) can be a problem in low planting areas, so it’s important to manage it from the outset.  

• This article is adapted from the fourth in a series of nine DairyNZ Farmfacts on managing waterways on farms. They can be viewed at www.dairynz.co.nz in the Farmfacts – environment section.