Building resilient landscapes after fire and drought

This workshop examined rural landscape issues emerging as a result of prolonged drought and recent bushfires. The workshop was held in Bombay, just south of Braidwood. Led by Andy Taylor from South East Local Land Services (SELLS) in Braidwood, the workshop was an opportunity for local farmers learn about actions they can take to mitigate the effects of erosion. We also learnt from Judy Carmody about the support available from the Rural Mental Health Resilience Program and Felicity Sturgiss, Senior Land Services Officer (SELLS), talked to us about ways to support wildlife after fires.

Andy Taylor has written a handy guide to managing erosion after fire.

Jane Ambrose from Upper Shoalhaven Landcare talked about Landcare in the area and how to get involved in the projects they run. Jane kindly agreed to share her notes from the workshop which can be downloaded below.

The key points from the workshop were:

  • The scale of the drought and fires has made erosion events more likely due to lack of ground cover. A question asked at the workshop was “How do I to prioritise erosion control activities?”. Andy suggests using Six Maps to calculate the catchment size above an erosion point and prioritising groundworks on the gullies with the largest catchment. You can slow water higher in the landscape by using grazing management to maintain ground cover and sediment traps to slow water run off.
  • Understanding your soil type is vital for remediating erosion. Around the Bombay area, where the soils are sodic and highly erodible, protecting the topsoil is critical to prevent erosion. Information about your soil type can be looked up on eSpade along with soil testing results for your area. Here is the eSpade link and an example of the soil report you can get from eSpade.
  • Dams and rivers away from the fire grounds have been adversely affected by debris from ash, soil and dung. These contaminants can cause water quality issues for stock, fish and other water users. It is possible to build a sediment trap above a dam using vegetation, rocks or a sediment fence to slow down the movement of water into the dam so that debris is dropped in the trap before the water reaches the dam. This will improve the quality of the water collected in the dam.
  • Repairing containment lines created by bulldozers during the fires is important to reduce erosion. Replacing the topsoil with a grader is a good way to start. Mitre and roll over drains can help slow down and divert water in steep sections. Weed free hay bales can also be used as sediment traps to slow water movement.
  • Because of the intensity of the recent bushfires, the seed bank in the soil could be depleted. A hot fire can change the soil chemistry including soil pH and soil structure. Generally speaking, native grasses have evolved with fire and will recover better than introduced species of grasses. Perennial grasses with deeper root system can also recover well, depending on how hot the soil surface became. Consider using sterile Rye Corn to help establish groundcover. Rye Corn is a better choice than other exotic species on sites with high conservation values where you don’t want to introduce weeds and new exotic grasses. Branches, jute mesh, rocks and other vegetation can all be used to slow down water and create niches for plants and pastures to establish.

Felicity and Andy reiterated the importance of biosecurity when planning erosion works and when feeding wildlife. For example, use straw or other inert materials for erosion management rather than hay or materials containing seed to prevent the spread of weeds. Seek appropriate advice on what to feed wildlife in fire affected areas and avoid feeding meadow hay that could accidentally introduce weeds.

The following are links to more information:

Understanding the impact of the 2020 fires

Building a sediment fence

Pasture recovery after fire

Fire retardant plant list from Yarralumla Nursery (but remember all plants can burn)

Bushfire Customer Care NSW Government

Healing the land techniques for managing erosion workshop summary

The Small Farms Network Capital Region received funding from the Every Bit Counts project. The Every Bit Counts project has been funded by the New South Wales Government through its Environmental Trust.

Healing the land: techniques for managing erosion

Community spirit, professional expertise and practical demonstrations were a feature of this erosion and revegetation workshop. Guest speakers David Hilhorst and Andy Taylor from South East Local Land Services and Scott Soper led an inspiring and educational day.

One of our participants Chris Curtis has kindly agreed to allow us to publish his notes and photographs from the day – see the link below.

Erosion workshop notes PDF

This wattle is providing protection to help other plant species to grow

Here are more ideas and strategies from the workshop.

Pioneer plants such as wattle add nitrogen to the soil and improve soil fertility and structure. You can use branches from these plants (preferably with seed attached) and lay them over bare ground to create a nursery for seeds and/or or tube stock.

Locally grown small trees including wattles, kunzea and tea tree can be lopped and placed strategically on an eroded gully floor, the branches can be bundled and pegged creating a brush raft. The raft areas catch sediment that can be direct seeded using native grasses, sedges and rushes.

Look for wet patches above and below small erosion head cuts and use these sites for revegetation using locally sourced plants. Use bendy plants that slow the speed of the water including Juncus species, Carex appressa and Lomandra species. Trees that grow thick trunks should be avoided in confined gully beds and streams because tree trunks can deflect flood waters into banks and exacerbate the erosion problem.

Protect your soil from erosion is by maintaining 70- 80% ground cover in your paddocks and by limiting stock access to dams and dam spill ways. Erosion can be caused by overland flows from vegetation removal, dams, roads and gullies and by subsurface water movement. You can use simple clues to help you read your land, for example, are larger trees dying in patches? This could indicate that salinity is a problem. The eroded site at the property we visited was most likely being impacted by saline ground water which we learned also affects the water quality in the dam.

Mapping shallow ground water with an electrical conductivity survey gives an insight into the depth of the water resource and the salinity of an area. Windellama Landcare owns electrical conductivity (EC) mapping equipment and it can be hired for use by property owners and contractors. You should seek advice from South East Local Land Services to help you plan your erosion control work and EC mapping – Contact your Local Land Services office.

Learning how to do a simple sodicity test

Sodic soil demonstration by Andy Taylor and David Hilhorst

 

 

 

 

 

 

 

An example of sodic soil at the site in Bungendore

Eroded patches of sodic soils in gullies look like candle wax or stalactites. You can do a simple sodicity test using a small clod of soil and a clear dish. If area around the clod becomes cloudy, this indicates that the soil is sodic and might be highly erosive.  Soil sampling of your farm could help you decide if you should be planting salt tolerant species at an eroded site.

Saline and Sodic Soils – the Difference video

Weirs, rock structures and rock/wire mesh weirs are all examples of “controlled activities” that may require a permit. Contact the Office of Water for advice about building structures including dams in drainage lines. As a general principle, water should always be returned to the same drainage line not diverted to another site. Before undertaking major works in water courses and gullies it is wise to check that your contractor has sought the correct approvals.

Contact a water regulatory officer as listed on the Office of Water website, call the licensing information on 1800 353 104 or email information@water.nsw.gov.au for more information.

Stabilising an erosion site above a dam. The hessian rolls were filled with mulch and compost and seeded with grass seed.

Jute or hessian can be used on bare eroded sites to create zones where vegetation can be established. ‘Burritos’ can be made by wrapping jute or hessian fabric around a mixture of forest mulch and compost which can then be laid on the contour and held in place using wire pegs. Mulched areas can then be seeded with a soil conservation grass mix or local native grasses. Once micro climates have been established other plants can be encouraged to grow using the brush raft technique described above.

 

Weeds such as blackberry and serrated tussock can be used as a resource to help provide mulch, organic matter and plant cover at eroded sites if they are already growing there. It is important though to manage weeds to prevent flowering or setting seed by cutting, spraying or manual removal. Chip and spray the weeds or cut the canes and leave them in situ on the gully floor or bank, this slows the flow of water and traps sediment. The area can be then planted with desirable plants and grasses. The thorny plants can act as protection for new plants during establishment. Continual monitoring of weed prone sites is important.

The SIX Maps website can be used to  work out the size of the catchment for an erosion head cut. For example, using SIX Maps, Andy Taylor estimated that for 1 in 50 year high rainfall events, the gully on this farm would have one tonne of water per second flowing over it. That is equivalent to one intermediate bulk container (IBC)/second. Estimating catchment size, soil testing and electrical conductivity testing are just some of the tools that can be used when planning erosion control measures.

Further information and resources

Gully Erosion Assessment and Control Guide

The Farm Dam Handbook

Rural Living Guide – A guide for Rural Landholders in the South East

Guide to Managing Ground Cover – MLA

DPI Erosion Website

Grassland Flora – a field guide for the Southern Tablelands

Native tree and shrub resources

SIX Maps – mapping tool

This event was made possible with funding and in-kind support from South East Local Land Services.