Interest in regenerative farming methods is on the rise, and trials across 20 Victorian farms are showing producers exactly how increasing soil carbon can lead to food production and climate change benefits.
Led by the Heytesbury District Landcare Network (HDLN), the Bostocks Creek project reveals how on-farm application of multispecies forages, soil ameliorants, bio-fertilisers and tillage methods are leading to changes in soil health, pasture growth and improvements in soil carbon and nutrient levels.
HDLN coordinator Geoff Rollinson said the project aimed to help farmers trial strategies to improve soil carbon sequestration, potentially improving their soil and animal health and farm productivity while reducing greenhouse gases to mitigate harmful climate impacts.
Four types of tillage methods were used in a single paddock sown down to multispecies pasture; this included rotor strip-till, soilkee, vaderstadt and power harrows to find if there were differences in the outcome.
"Interestingly, soilkee (a low impact tillage method) is also used on a farm in Gippsland, which is the only one to have gained soil carbon credits in Australia," Mr Rollinson said.
"In a paddock where there is very well established and persistent ryegrass, we found the power harrows and rotor strip-till (which are slightly more aggressive forms of tillage, even though they are still classified as low-tillage machines) had a better result in that there was more disturbance of the soil and more opportunity for the multispecies pasture to establish," Mr Rollinson said.
Testing in late spring 2021 on the trial plots examined whether treatments had raised soil carbon or organic matter and nutrient levels.
Carbon is measured by extracting core soil samples to varying depths, generally between 0-10 centimetres, but can also reach depths of 10-30cm and beyond 30cm.
"These core samples are sent to a laboratory and you receive all sorts of information such as organic soil, carbon content, soil moisture, a list of macro (nitrogen, phosphorous, potassium and sulphur) and micro-nutrients," Mr Rollinson said.
"You can also compare these tests with a visual soil assessment by taking a non-laboratory approach that usually involves digging a cube of soil to make some observations; are there a lot of worms? What does it smell like?
"The colour indicates how much humus and carbon might be in the soil.
"There's a benefit in doing a visual soil assessment and seeing how that correlates with the lab results."
Mr Rollinson said the results revealed overall that there wasn't as much of a shift in carbon levels as was hoped as far as the project goals were concerned.
Initially, it was hoped carbon levels up to 8 per cent could be reached, however, carbon levels were around 4.9-5.1pc aggregated across all the properties.
Baseline soil tests and dry matter yield tests revealed significant variations in soil carbon and organic material levels across the different farms and soil types.
"There was a reasonable amount of variation from property to property, which is no surprise," Mr Rollinson said.
"Based on that, if the project target was to achieve 8pc, we determined that it would probably take seven to eight years to reach those levels if you look at the tables and trend lines.
"Interestingly, we received comments from the lab saying, they're extremely high levels of carbon at 4.9pc to 5.3pc.
"A lot of it has to do with farming methods and the rainfall levels.
"The further north you head, you are more likely to see carbon levels of 2pc or 2.5pc typically in cropping regions."
The trial incorporated a wide range of pasture species, using between 12 and 16 different species in a single paddock.
Healthy Farming Systems agronomist Jade Killoran was part of the project team and worked with the individual landholders to tailor the species selection according to soil type and whether it was an autumn or spring planting.
"I try to include a mix of brassicas, broadleaves, legumes and grass species to maximise diversity," Ms Killoran said.
"There are many benefits to diversity, including supporting and developing a diverse soil biological population, sequestering carbon and improving fodder production across the season (including summer), and increasing nutrient cycling and nutrient and water holding capacity."
Some of the common species used include:
Mr Rollinson said taking a different approach to pasture selection and sowing down multispecies pasture had many benefits for farmers and cattle, which are happier because of the variety in their diet.
"Not only can you tailor multispecies to varying soil and seasonal conditions, but when you have a traditional pasture of just ryegrass and sub-clover, you don't cover five different plant groups in the selection," he said.
"With a conventional pasture system, you might only get two to three tonnes per hectare of dry matter, but with the multispecies pasture, you walk into a field of it is just wonderful all these different plants and flowers and you might be in waist-high pasture rather than pasture that's only four or five inches off the ground.
"It's not unusual to have double or treble the amount of pasture come out of those multispecies pastures.
"A lot of dairy farms are rotating paddocks every 24 or 25 days, with these systems when you have that amount of pasture you can get stock rotations of up to 60 days, which allows the pasture to grow more.
"Also it has a benefit as far as their gut bio-health is concerned, with the introduction of good bacteria."
"Because of this, some project farms have dramatically reduced their vet bills."
Craig and Tanya Davis operate their dairy near Cobden, south-west Victoria.
They milk about 600 predominantly Holstein cows within a 50 unit rotary unit supported by an aggregate of 600 hectares.
There are 50 paddocks on the main farm, some of which are irrigated.
The Davis' have been steadily improving their pastures by reducing the amount of ryegrass in favour of cocksfoot and hummer, which are deep-rooted and bug resistant.
The average annual rainfall for the area is 750-850mm.
The Davis farm used all four tillage methods in the trial.
The paddocks were sown at the same time, with the same multispecies pasture forage mix.
Mr Rollinson said while it would be ideal to run the trials over four to five years, to examine the significant changes in the soil and gather a greater breadth of data, even at an early stage you could see a significant difference in pasture growth based on the tillage type.
"Currently, they are trialling multispecies pastures as part of their pasture management system," he said.
"The Davis family has been focusing on establishing deeper-rooted pastures, rather than shallow-rooted annuals, as they move into more perennial-based pasture systems."
Their annual milk production is about 5.8 million litres (9000 litres per cow).
Milkers are fed 10 kilograms of dry feed per day or 1700 tonnes per year, with 80pc grain (mostly wheat) and 20pc high protein canola and lupin seeds.
Turnips are grown under irrigation as a successful supplementary crop, and the farm produces its own silage (about 1000 tonnes per year on the out paddocks) and hay.
The undulating land on the main farm has a range of soil types, including heavy clay flats, some volcanic soils and loams.
Milkers have a 21-day pasture rotation regime, including movement between day and night paddocks.
The Davis family is in somewhat of a transitional phase.
They are one of five families forming the Green Pastures Movement, with a commitment to providing healthy products from healthy farming practices, and in the process, they tell the whole story from paddock to cereal bowl (or coffee cup).
The Davis' are also earlier adopters of utilising compost from their own property, which they have been doing for approximately eight to 10 years.
Effluent from the dairy is diverted to two effluent ponds, with solids from the first pond composted with calf bedding and other available materials for field application.
Humates are added via a ring drain to increase the nutrient value, while gypsum is added before field application, resulting in very little expenditure on fertiliser (less than $30,000 per year and steadily decreasing), and a reduction in weed infestations.
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Soil tests carried out across the farm in 2016 indicated relatively low levels of soil carbon in some paddocks (less than 1pc) but higher levels in some other paddocks (4.3pc).
"They have found that activating the soil biology has reduced their reliance on fertilisers, and it has also encouraged re-depth in their pasture systems," Mr Rollinson said.
"By reducing their reliance on synthetic fertilisers, they are saving money, and it's a win-win in terms of maintaining soil biology."
In April 2021, in between Covid-19 lockdowns, HDLN held a field day at Bostock Hall.
Organisers expected 20-30 people but instead ended up with 70 farmers in attendance.
"That's an indication of how strong the uptake is of these regenerative farming practices," Mr Rollinson said.
"There is an increasing level of interest in chasing carbon credits."
Currently, there are between 200-300 projects registered, but few have been granted carbon credits as the process of approval is lengthy.
"The carbon credits aspect is the starting point for farmers transitioning to the regenerative model in an effort to improve soil health and pasture yields, and if in the process over a period of time they can claim carbon credits then that's a bonus from a financial point of view," Mr Rollinson said.
"Also, from a social licence point of view, many consumers are walking down supermarket isles noticing which food is being produced as a carbon-neutral product.
"So while it's not a huge money earner for farmers at this stage, it certainly satisfies that consumer-driven desire for carbon-neutral food."
Mr Rollinson said it was early days in terms of the methodology used, engaging carbon brokers, and reporting and recording carbon levels.
"From a cost and ease for farmers perspective, access to the carbon credit scheme is not where it needs to be broadly speaking, but we are probably not too far away, particularly as the government has opened up the carbon market so to speak," he said.
"I imagine in about 12 months, it will be easier to access the scheme, and it will probably become more important to farmers."
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