By Philippa Noble
Farm Forestry Team Leader
A Rutherglen farm has demonstrated that farm forestry can offset all the emissions from their prime lamb production. Running 500 crossbred ewes on 120 hectares of pasture, the farm has established trees in every corner and crevice of the property, including along fence lines and irrigation check banks and on blocks in unproductive areas.
Every tree is made to work, not only to provide stock shade and shelter from the ever increasing hot days but to lock up carbon and to produce a product, either high quality sawn timber or biomass for heating and potentially electricity production.
Using carbon calculators developed by the University of Melbourne and the Federal Government’s Greenhouse Office, the agricultural emissions from the farm were determined to be equivalent to 183 tonnes of carbon dioxide before the trees were taken into account.
The farm greenhouse gas emissions were mostly methane from the sheep enterprise, not carbon dioxide. Being a ruminant animal, sheep rely on bugs in their gut rumen to do the heavy work of digesting the roughage in their diet. Some of these bugs produce methane which is burped out by the animal during rumination. Methane is a serious greenhouse gas that is highly efficient at trapping heat. It is 21 times more potent than carbon dioxide and it lasts up to 10 years in the atmosphere before breaking down.
Options to reduce methane emissions from the farm are limited to making sure high productivity is achieved from every mouthful of grass that is eaten. This is an aim that every farmer strives for.
Researchers are only now beginning to find other ways to reduce the actual methane emissions from ruminants, such as adding specific oils or tannins or probiotics to the sheep’s diet. Studies into the most effective additives are still underway, with a lot more work needed to find out how to use these in an extensive grazing system.
While researches look to refine ways of reducing methane from the rumen livestock, farmers still have the option of offsetting their emissions by growing trees.
There are 10 ha of trees integrated into the Rutherglen farm which are locking up 163 tonnes of carbon dioxide in the above ground portions of the trees. When the carbon from the soil, roots, debris under the trees and in the product is taken into account over a 30 year period, the trees were calculated to lock up 275 tonnes of carbon dioxide per year.
Timber is a product that not only locks up carbon, but can be substituted for many high energy intensive products such as steel and concrete. It can also be used as a replacement for fossil fuel energy production.
The value of trees for our changing climate is much more than just the shade and shelter they offer to farmers, they can play a key part in helping farmers offset their emissions.