Georgie Keynes, Technical Facilitator, BIGG
Rehabilitating a watercourse is a brilliant way to improve water quality, reduce erosion, provide habitat for birds and to improve on-farm production however, how do you select the most appropriate plant community to do the job?
With the support of the NR AMLR and the 25th Anniversary Landcare Grant Scheme Funding, the Barossa Improved Grazing Group (BIGG) are helping landholders investigate how effective different native plant communities are at achieving this rehabilitation process.
The Project aims to explore and demonstrate the native plant communities that provide 100% annual ground cover to help stabilise the soil, prevent erosion and reduce run off and communities which improve habitat for birds by providing perching, nesting and feeding sites. In addition the cost/benefit of the processes will be compared across the different communities.
Working on the Klemm’s dairy farm in Moculta, the Project, which began in May 2015, fenced off a 250m length of watercourse which runs during the winter months and was significantly pugged through the summer months. Groundcover levels through the centre of the watercourse measured 10-20% with areas along the bank being completely bare. Woody weed removal of over 20 Briar Rose plants, Artichoke and thistles and a plant species survey and bird survey were performed prior to planting.
Tubestock was planted in July after a shroud spray to remove the initial weed completion. 20 metre plots of the following plant communities which are local to the area, were replicated and compared against three control areas:
- native grasses including wallaby, kangaroo and spear grass
- understory plants (approx. 60cm tall), including juncus sp., lomandra and hardenbergia
- tree’s including sheoak, peppermint box and red gums
- trees and mid story plants including acacia sp., busaria and dodonae.
Due to the extremely dry spring, the plants were watered in October, December, January and early March.
Year 1 Results
The most noticeable results one year after fencing is the reduction in pugging and the increased groundcover which measures between 90 and 100% across the entire site. These levels would significantly reduce the risk of erosion and run off, improving water quality and demonstrate the effectiveness of simply removing stock from the watercourse area.
Considering the dry conditions, the majority of the plants have survived extremely well with over 70% survival rate, with the majority of losses occurring within the understory plant plots. Interestingly the majority of Juncus species planted did not survive, however plants which were originally there have thrived and flourished with the removal of stock demonstrating a much cheaper option to tubestock planting!
Weed control has been a continual problem with caltrop, which was already present in small numbers, flourishing in the areas which were sprayed out for plants. As competition from the native plants increases, the caltrop is likely to reduce and will be measured in subsequent years.
Plans for the future
The Project in its second year will fence off an adjacent section of watercourse to determine the cost effectiveness of machine direct seeding.
In following years, as the plants become more established, the bird and fauna surveys will be repeated. Production benefits of increased pasture production through rotational grazing and the improved milk production as a result of shade and shelter for the cows will also be determined.