Low-Carbon Farming

Becoming a carbon neutral producer by Jenny Hall

The whole point of carbon foot printing is to keep us below the 450 to 550 CO2 equivalent parts per million in the global atmosphere. This is known as the tipping point of irreversible change. According to the Carbon Trust emissions should be calculated using the standard yardstick of carbon dioxide equivalence with methane having a 21 times co-efficient and nitrous oxide a 310 times co-efficient of carbon dioxide. Clarion Award winner Chris Goodall in How to live a low-carbon life has produced this useful table.

The Main Sources of Greenhouse Gas Emissions in the UK Food Chain (Goodall, 2007)

The UK is a net food importer and this table does not include the greenhouse gas emissions incurred growing food in other countries for use in the UK. Reliably estimating this is extremely difficult but obviously the figure of 2.1 tonnes is in reality higher. Differing figures from the Goodall table will occur in other publications but the importance of this table is to give an overall impression.

Tillage the double carbon whammy

Also excluded from the Goodall table is the loss of carbon as a result of tillage. Across the UK the carbon loss from soil as a result of tillage may be as high as 13 million tonnes CO2/yr (Cranfield University). Tillage causes CO2 emissions through exposure to air (accelerated past 25°C) as well as fuel to run the machinery. I think both should be included because at the end of the day they are a consequence of food production. Organic farming will always score better later in the audit because of the carbon sequestering within biological cycles. Including the CO2 tillage loss will lead to useful information and arable production being viewed as only available for necessities. For example, to feed everyone organically from closed-systems (defined below) their healthy wholegrain cereals, potatoes, green veg, root veg, alliums, pulses, nuts, seeds, fruit and Omega 3 plant oils will take all the "4. 3 million ha" UK arable land without resorting to imports (Dave, Growing Green International 2007). The carbon auditing of soil will put soil health at the centre of good husbandry.

Permanent pasture sequesters 4 tonnes/CO2/yr and so should not be ploughed up to accommodate luxury arable crops. Biofuel can be singled out as a definite carbon-neutral no no despite claims to the contrary in farming audits. Professor David Pimentel has shown that there is no energy benefit of using biomass for liquid fuel. In the case of maize it requires 29% more fossil fuel to grow and process it. There is also a social implication.

“If you start to fuel cars with crops," says Ed Matthew of Friends of the Earth, "you are instantly putting the world's one billion starving people in competition with the world's one billion motorists. It's as simple as that."

In this matter willow needs serious consideration as it can be grown on marginal, non-arable land with grass strips in between. It can be used for heating, electricity generation and basketry. Research by the University of Cardiff found indications that growing short rotation coppice willow in the uplands is a viable proposition with regard to establishment success and yields. In the event of a secure wood chip market in Wales, returns to the grower would be comparable to those from sheep production. Could coppice wood fuel renewable tractors powered by steam for high draught requirement and support solar-electric tractors for light work of the future?

The carbon neutral farm

The Carbon Trust is trying to develop standards in this area and they urge that there is a need to strike a balance being analytically rigorous and at the same time being practical. It would be impossible to conduct full lifecycle analysis of organic produce including its domestic cooking and final waste disposal. Instead it should stop at the door of the final consumer. Cradle-to-door analysis will allow localised direct marketing of produce to score well and assist regional, national and exporters to improve their CO2 track record. All primary producers would trace their product and could not claim carbon-neutrality unless they had something approximating a closed-production and localised-distribution system. We should strive for carbon-neutrality on-farm and not through carbon offset schemes that have been shown to have dubious value and are misleading to consumers.

What should we measure on the farm?

The direct inputs are already out in the public domain although there are sometimes discrepancies between figures. It is important that as a movement that we all stick with the same figures using the best available knowledge. On the indirect side, the Carbon Trust, Britain’s leading authority does not include workers commuting to work. However, I think the commuting fuel of workers would be straight forward to work out and would encourage multiple vehicle use or pedal power. In some of the audits I have seen there is no attempt to include “indirect inputs” which is very misleading to consumers. The indirect inputs in conventional agriculture are what make it energy intensive in comparison to organic. To not include them is to allow the analysis to say that conventional agriculture may be better for the environment. According to the Carbon Trust each raw material process needs to be detailed back until it is possible to identify primary raw materials which have zero associated green house gas emissions. The chain for recycled materials starts at the point they are handled so in the case of off-farm manure or green waste compost when they are initially collected for stacking or windrowing.

Within the on-farm analysis, the real biggies are the capital outputs. The rest of the carbon auditing sector is not including them but that’s not to say the organic movement should follow suit. I feel that there are significant problems with pretending it is not an issue. After trawling the internet, it seems Caroline Saunders and colleagues at Lincoln University, New Zealand have taken this further than anyone following on from the methodology of Colin Wells also from New Zealand. I don’t agree with their conclusions that globalised food is better for CO2 emissions but their methodology is thorough. For all capital items the same methodology is used. This involves estimating the total mass of each component and multiplying by an appropriate energy coefficient that represents the sum of embodied, manufactured and maintenance energy costs. The annual capital inputs CO2 charge to the farm is then calculated by the expected working life of the item by assuming straight-line depreciation. For example in the research a tractors working life was treated as 15 years and farm implements as 20 years, which would be really good news for us producers who are using ancient machinery. As for buildings this is calculated on a metre-squared basis. These figures have already been calculated and including them would encourage carbon-friendly practices of buying second hand machinery, reuse / repair of existing machinery and effective use of farm buildings.

Rewarding Renewable Energy

Embodied energy within renewable energy sources, like the galvanised steel for a wind turbine mast, is also an issue that would need to be included in a similar way to farm machinery. I would recommend watching the Cuba film because it is an uplifting film of people living organically and within the limits of their environment. The one thing I thought was really good was the small amount of fossil fuel they had was invested into developing renewable resources, particularly solar energy, as this benefited the most people. I would like to see this developing in the UK, as a not too intrusive wind turbine could easily provide the energy for a household and a packing operation. Solar-electric tractors are being developed in the US and wood chip steam units could be developed for conversion of existing tractors.

Past the Farm Gate

As I have suggested the CO2 flows should be cradle-to-door of the final consumer and definitely not cradle-to-farm gate which would again be misleading to consumers. Therefore, production and retailing needs to be separated in what is known as “co-products separation”. Splitting upstream emissions is standard practice and can be based on their energy content, price or mass. For our box scheme, price would be the most appropriate technique. This year we have grown 60% and bought in 40% of produce, so we should only measure the 60% and not the bought-in retail produce (that would be measured by other primary producers’ audits). The pack house and distribution CO2 flows would need to be split 60/40 at the same ratio. Although this sounds complicated an easy to use computer audit package could automatically sort out these percentages with no problem. For producers that do not directly market their produce, and where the figures are not readily available estimates would be made on “mostly likely” route and mode of transport. This needs research and consultation.

Carbon Sequestering

Buying in manures, compost, compound fertilisers, grain-feed, P&D products will undoubtedly increase our carbon emissions. Within the practicalities of UK agriculture, our ultra-carbon sequestering farms will find the majority of their fertility coming through the post in the form of green manure seeds or from perennials plants on their holding. If we aim for closed-systems then we are getting closer to becoming carbon sequestering superstars! By summing permanent grassland, green manures, field margins, beetle banks, wild areas and agroforestry areas, we should be able to arrive at some sort of figures for carbon gains. On this point it is worth pointing out soils with clay content lower than 20% are disadvantaged because they need to do more fertility building. Perhaps within the equation a special adjustment could be made.

Conclusion

To summarise, the approach to auditing carbon footprints for organic producers requires consensual central planning with a methodology that is achieved through an active consultation process. This article will hopefully provoke you to think about the things I have missed. We definitely need to reflect the actual CO2 flows of organic produce including the indirect CO2 flows and capital outputs because in an economy they are too significant to be ignored. As a movement we should not claim to be carbon neutral, when we blatantly are not. We are already laying the ground rules so that we can keep the integrity of any carbon claims we make.