A grapegrower from McLaren Vale, Oli Madgett has co-developed an app that easily measures soil carbon. Here he explains how grapegrowers would benefit from finding out the soil carbon levels currently in their vineyards to enable them to take advantage of carbon credits available should they implement practices that lead to improvements in these levels.
The media typically paints growers as the victims of an increasingly extreme climate, and the 2019 season saw our own vineyard in McLaren Vale endure hail in November paired with record breaking temperatures in the region during veraison. If grapegrowers are to change this narrative, and become the heroes of the climate change story, it’s the soils of our vineyards that could well hold the key.
Soil has tremendous potential to sequester carbon, by taking CO2 from the atmosphere and locking it up in the ground. Globally, the carbon stored in soils is triple the amount in the atmosphere, and it’s been projected that sequestering additional carbon in Australia’s soils could contribute 30-40% of the country’s emission reduction targets.
Building carbon in soils is not only beneficial from an environmental mitigation perspective, but soil carbon is one of the best indicators of soil health, and increasing soil organic carbon improves both the productivity and resilience of vines. As well as the production benefits, growers also now have the potential to achieve a triple benefit from earning carbon credits for the increases they can make.
Through The Clean Energy Regulator, Australia now has a robust and clear methodology for farmers to use to baseline their initial soil organic carbon levels, implement new activities on their land, and subsequently go back in future years to re-measure.
The 2018 Carbon Credits Methodology ‘Carbon Farming Initiative – Measurement of Soil Carbon Sequestration in Agricultural Systems’ sets out the key steps that a grower needs to take:
• a Carbon Estimation Area (CEA) is drawn around the vineyard blocks that a grower wants to actively build carbon in
• the CEA is sub-divided into strata, which could simply involve dividing it into three strata of the same area, or the strata could be drawn to follow the main soil types of the vineyard, especially if future activities such as spreading inputs are going to follow those zones
• random locations are then created in each strata where soil tests need to be carried out by an independent soil coring contractor
• the minimum requirements are for the soil core to be 38mm in diameter, with the sample taken from the top 30cm of soil; growers might want to sample down to 100cm so that they capture the main root zone, and a deeper sample would be advisable if mid-row ripping is planned which would be disturbing the soil at greater depths
• soil cores are independently tested at an accredited lab, which creates the baseline soil organic carbon, and bulk density results if growers do want to apply for carbon credits, then they need to pass the test of commencing a new activity, which could include planting mid-row crops, addressing soil constrains such as acidity, sodicity or nutrient deficiency, spreading mulch or compost; if these have been previously carried out, then the new activity could be microbial inoculation of the inputs
• auditable records need to be kept of the new activities that are carried out in order to build soil carbon
• to be eligible for carbon credits, the soil in the strata needs to be re-tested in future years, with the first test happening within four years of the commencement of the project; there are also some withholding periods to note for the application of organic materials such as compost before re-testing
• to successfully apply for carbon credits, there is a requirement to commit to not changing the usage of the land for 25 years from the point at which the new activity commences, and that typically fits in well with the time horizons in viticulture.
As a co-developer of Platfarm — an app that enables agriculturists to readily utilise soil and vigour maps to precision manage their land on the ground — we’re working on software that helps growers to compliantly baseline their soil organic carbon levels, supporting farmers and viticulturists to increase and document the changes and activities over the coming years.
A reasonable level of increase in vineyard soil carbon to target would be from 1% today to 1.5% in 10 years’ time, which would be a realistic target in that time frame; an increase to 2% would be a great result (Minasny et al. 2017).
Agriculturists have typically worked with a third party aggregator such as Corporate Carbon or Carbon Link to identify opportunities to create carbon credits and assist in following the guidelines to apply for the Australian Government carbon credits scheme. There is also an emerging voluntary market where companies and consumers are directly purchasing carbon credits from farmers through marketplaces such as Nori.
Earning carbon credits should generally be seen as ‘the cherry on the top’ rather than the driving reason for changes in vineyard management practices, with the decision to actively build soil carbon levels based on the ability to increase production returns at the farm gate through improved soil performance resulting in more resilient and productive vines.
The Olsen family own a livestock property in Gippsland, Victoria, and recently became the first farmers in Australia to receive soil carbon credits under the Emmission Reduction Fund, receiving a total of 407 credits from the Clean Energy Regulator for increases made on their 100ha trial site. The credits were the first to count towards Australia’s national targets under the Paris Agreement and were also the first soil credits worldwide to be eligible under The Paris Agreement. The Olsens increased their soil carbon levels by using a Soilkee implement they invented which helps to aerate soil and by planting bands of mixed species of grasses and cover crops. With these soil improvements, they’ve been able to increase their stocking rates by 20-30%, working towards a 100% production gain within the next 10 years.
Consumers are also becoming more aware of the carbon footprint of products, and this trend has contributed towards Meat & Livestock Australia committing to work towards the red meat industry being carbon neutral by 2030.
From a wine industry perspective, Keith Tulloch Wine in the Hunter Valley recently joined Ross Hill Wines in Orange in becoming the first producers to be certified as carbon neutral. Hopefully this will create industry-wide momentum focussed on our ability to use our vineyards’ soils to create more resilient vines, and build a sustainable future for grapegrowing.
Reference Minasny, B.; Malone, B.; McBratney, A.; Angers, D.; Arrouays, D.; Chambers, A.; Chaplot, V.; Chen, Z-S.; Cheng, K.; Das, B.; Field, D.; Gimona, A.; Hedley, C.; Hong, S.K.; Mandal, B.; Marchant, B.; Martin, M.; McConkey, B.; Mulder, V.L.; O’Rourke, S.; Richer-de-Forges, A.C.; Odeh, I.; Padarian, J.; Paustian, K.; Pan, G.; Poggio, L.; Savin, I.; Stolbovoy, V.; Stockmann, U.; Sulaeman, Y.; Tsui, C-C.; Vågen, T.G.; van Wesemael, B. and Winowiecki, L. (2017) Soil carbon 4 per mille. Geoderma 292:59-86.
This article was originally published in the May issue of Grapegrower & Winemaker magazine. To subscribe, click here.