Improve farmland by storing and increasing carbon and reducing salt scald
Nuts and Bolts
- About 130 native grasses occur in the south west of WA.
- Native grasses have evolved to be persistent in a dry and fluctuating climate.
- Tolerant of low inputs of fertiliser, herbicide and lime.
- Good for grazing animals as they provide choice and summer active varieties extend the growing season in summer and autumn.
Perennials increase production
Compared with current annual-based systems, perennial pastures introduced into Australian farming systems offer an acceptable balance between food and fibre production as well as environmental benefits. Perennial pastures’ ability to utilise dry season moisture extends the growing season in summer and autumn, thereby increasing production potential. Along with this direct economic benefit, perennial plants have a vital role in improving land degradation (e.g. salinity, erosion, acidity) through their deep root system which in turn, prevents loss of potentially productive land. South Coast NRM have been working with farmers to plant perennial pastures across the south coast.
Native perennials suit a changing climate
Over recent years introduced perennial pasture species have been widely adopted in WA. Native perennial pasture species are not as widespread. There are more than 430 native grass species in WA including about 130 in the south-west, most of which are perennial. The major advantage of native perennial pastures is their adaption to local environmental conditions. Many Australian grasses have evolved in a dry and fluctuating climate and this ability to survive periods of moisture stress is particularly valuable (Lodge, 1994). Although native perennial species are generally considered to be less productive than introduced species, higher adaption to local environments, including marginal land, could make this system more productive in a changing climate (Moore, 2006). Australian temperatures are projected to continue to increase and average rainfall in southern Australia is projected to decrease (Bureau of Meteorology, 2014). Therefore native pastures could offer a stable solution to these conditions.
Native perennial pioneers in WA
Despite native perennial pastures not being a popular option yet in WA compared to the eastern states, Kendenup farmers Tim and Val Saggers have not been deterred. They have established native perennial pasture for more than a decade on their 1,200 acre (480 ha) property with the primary driver being solutions to environmental degradation.
Tim and Val’s farm was severely salt affected making parts of the property completely unproductive. Initially they concentrated on planting native salt tolerant perennial species to improve the salt scald areas and to drought proof the farm. Native pastures are resilient to drought conditions thereby offering some feed security for livestock during dry conditions. At the same time, the Saggers’ were very passionate about conserving and restoring the environmental system on their farm.
”We are really glad we didn’t buy a perfect farm as we are really excited about developing it and bringing back the degraded parts severely affected by salt,” Val Saggers said.
“We were not interested in introduced species and were keen to trial native perennial pastures, creating an environmentally managed farming system”, she said.
Trial, error and patience
Tim and Val found establishing native perennial pastures in the degraded areas was very challenging. It took trial, error and patience to select the right species which would establish, survive and persist over time. A decade on and the salt problem has drastically improved on the farm. These once unproductive areas have become a grazing option for sheep.
Although longer commitment time for establishment could be a barrier, collection of local seeds reduced the cost which was an advantage. Native perennial grass seeds can also offer an alternative source of income in native perennial pasture practice (Moore, 2006).
“It is nice to see our land is green and not degraded anymore,” Val said.
“Native perennial pastures, especially native grasses, have had huge mental health benefits to us seeing an improvement in the salt scald areas of the farm over the last 10 years. This keeps us passionate and makes us more inspired to keep farming in an environmentally friendly way.”
There is little recent information available on the production that can be expected from native grasses in WA but Butler (2008) showed an increase in live weight of lambs predominantly grazed on native grasses in Merredin (see Figure 1).
Figure 1. Average monthly growth rates of Dorper cross sucker lambs predominately on native grasses, Merredin, 1999-2000 (R. Butler, 2008).
Native perennials and soil carbon
The couple are also interested in soil carbon on their farm as a means of continuing their environmentally managed farming system.
“Our aim was to build up biomass in the salt affected areas by using native plants such as the chenopods (samphires, saltbushes, blue bush and rhagodia), acacias, eucalypts, casuarinas and native grasses (kangaroo grass and wallaby grass), ” Tim Saggers said.
Carbon farming aims to assist in mitigating climate change, seeking to reduce emissions in its production processes, while increasing production and sequestering carbon in the landscape. Perennial pastures are generally expected to store more soil carbon than annual pasture due to their highly developed root system.
An assessment of soil carbon was conducted in December 2012 in a stand of native perennial pasture kangaroo grass (Themeda triandra) (Figure 2). Although there was a slight trend towards the native perennial pastures showing higher total carbon and total nitrogen (Figure 3) than an annual pasture, the difference between them was not significant. At the time of testing, the native perennial pasture had been established for only three years. As native perennial pasture may be less productive than annual pasture over the first two or three years (Butler, 2008), a longer period of assessment might explore more details of carbon dynamics under a native perennial pasture.
“We could see our soil was improved just by looking at it, “ Val said.
“As a next step, it would be nice to know if we are seeing any benefits of increased soil carbon through adoption of our “environmentally managed farming system.
“The landcare over the past 10 years has really helped the salt scald land become viable again. Planting up the fragile areas of the farm with native perennials means the farm is more sustainable and productive for future use.”
Figure 2. Mean values of total carbon (particulate carbon, humus and resistant carbon) in each soil depth (0-10, 10-20 and 20-30 cm). Bars indicate standard errors of values in 0-30 cm soil.
Figure 3. Mean values of total nitrogen in each soil depth (0-10, 10-20 and 20-30 cm). Bars indicate standard errors of values in 0-30 cm soil.
Soil carbon assessment was consistent with the CSIRO’s Soil Carbon Research Program (SCRP) methodology measured by elemental analysis as described in the soil carbon analysis protocol of Sanderman et al. (2011).