Farm emissions and furrowed brows

Farmers must make a big contribution to greenhouse gas emission reductions or UK carbon budgets will be breached. Simon Evans investigates whether the industry is up to the task

Cows, NFUAsk the public to name the biggest climate criminals and they will probably mention coal-fired power stations, air travel or ‘big oil’. Leaping lambs, lowing cattle and fields of swaying wheat are unlikely to get a look in. Yet in 2008, UK farms produced greenhouse gases equivalent to 44 million tonnes of carbon dioxide, 7% of the national greenhouse gas emissions total.

If farmers were to do nothing about their emissions and left the remainder of the economy with the task of meeting the UK’s 2050 reduction target (an 80% cut from 1990 levels), it would actually have to cut emissions by an eye-watering 86%. And agriculture would still be responsible for more than a third of the residual total of annual emissions at the mid-century. This is not tenable.

Agriculture punches above its weight in terms of greenhouse gases and water pollution. It occupies three-quarters of UK land yet generates an annual income of £4bn, just 0.6% of GDP. The big problem with emissions from farming is that they are diffuse, spread over 300,000 holdings around the country, and result from natural processes. Policies and changes to farm management that could effect the big emission cuts required seem hard to come by.

And the level of emissions is itself uncertain. The inventory is based on estimated averages rather than measurements at farm level, so the margin for error is wide. Even so, the recent history of agricultural emissions augurs well, as they are estimated to have fallen from 55MtCO2e in 1990 to 44MtCO2e in 2008, a drop of some 20%. These emissions are mainly methane and nitrous oxide (N2O), both strong greenhouse gases, respectively 25 and 300 times more powerful than CO2.

Some 18MtCO2e of methane a year comes from the digestive systems of ruminants such as sheep or cows burping as they chew the cud, and from their manures. Bacteria consume a small proportion of manufactured fertiliser and manures added to soil, breathing out 25MtCO2e as N2O. Farm CO2 emissions from powering buildings and running machinery are small, amounting to an additional 4.6MtCO2. Mitigating this will be comparatively straightforward if the wider economy, electricity supply and transport fuels are decarbonised.

Bringing agricultural production back home

Farmers are proud of their past success, which is at least in part due to improved farm management. Use of fertilisers has fallen dramatically since the mid-1980s, meaning lower N2O emissions. And yields of meat and milk have increased for each animal reared; although of course this only reduced methane emissions as the total quantity of farm animals fell.

Yet our appetite for livestock products remains undiminished, so despite modest yield increases the end result has been greater imports of meat and dairy. Today, the UK imports 40% of all food consumed. It is now widely recognised that the nation has achieved much of its apparent success in cutting greenhouse gases since 1990 by exporting manufacturing to China, and a similar argument can be made for agricultural production, especially beef, pork and dairy.

A visit to the butter aisle at any supermarket replete with Lurpaks and Anchors confirms this. “There is no sense whatsoever in measures which simply end up pushing greenhouse gases abroad,” says Professor Allan Buckwell, policy director at the Country Land and Business Association (CLA), representing larger rural landowners.

There is a moral case for maintaining production at home too: a growing global population needs more food. “Climate change is important but feeding people is too,” points out Professor Brian Chambers, head of environment science at consultants ADAS.

UK farmers, then, are being asked to produce more food, or at least as much as before. And this should be achieved while reducing greenhouse gas emissions. In its UK Low Carbon Transition Plan setting out the path to 2050, the previous government asked the farming industry to come up with a voluntary plan to meet this challenge. It asked for an “ambitious but realistic” 11% cut in English farm emissions by 2020, against a 2008 baseline. Northern Ireland has not yet set a target, but Wales and Scotland are aiming to deliver a 10% reduction by 2020. As in England, Scottish government support for farm action is centred on the provision of information and advice.

However, the most detailed roadmap for reducing emissions is a joint agricultural industry action plan for England published in February by the CLA, the National Farmers Union (NFU) and others.1  This “firm statement of intent” to help meet the 2050 target outlines actions that the sector believes will deliver. The bulk of gains are expected to come from production and resource efficiency, it says.

While maintaining overall levels of production, farmers would turn out greater crop yields per kilogram of fertiliser. Livestock numbers might continue to fall, but this would be balanced by increasing yields per animal. In short, fewer cows would mean less methane. This could potentially allow more extensive farming, where each animal has more land. Other adverse impacts of intensive livestock farming, such as local air and water pollution and over-grazing, could also be reduced.

“Our plan focuses on practical measures we can implement now and for the foreseeable future,” explains Ceris Jones, NFU climate change adviser. “Farmers can actually do these things and they will make good business sense.”

That means, for instance, choosing crop varieties which use nutrients more efficiently or planning application of fertiliser so it is only used exactly where and when it is needed. The industry action plan advocates wider use of approved nutrient management tools. These can also factor in manure ‘dropped’ by animals in the field, so that its nutrients are properly accounted for.

The biggest gains in manure management are to come from using anaerobic digestion (AD) instead of simply storing and spreading residues on the farm. In AD, manures are warmed and fermented in a sealed vessel to yield biogas (methane) and a digestate which can replace fertiliser. The biogas is used to generate heat or electricity.

AD forms a key part of the action plan, which would see 20% of all manures treated by 2020 in 1,000 on-farm AD plants. The government is behind the idea, having pledged to promote a “huge increase” in AD (ENDS Report 426, p 22).

Recent proposals aim to ease the regulatory burden on AD plants (see p 50) and electricity generated from AD biogas will benefit from government feed-in tariffs that were introduced in February. However, NFU is concerned that the tariff for small on-farm AD is too low (ENDS Report 421, p 21). There are just 25 AD plants today, and most are used to treat food rather than farm waste.

Another area for the action plan is animal diet. “What you feed livestock has a big influence on methane emissions,” says Jon Moorby, a ruminant nutritionist at Aberystwyth University. Understanding the link between diet, productivity and emissions is a key area where much more work will be needed. Dietary components such as tannins, like those found in tea, can reduce emissions, says Dr Moorby. Tannins are naturally present in the heather that is common to upland farming areas.

More controversially, North American livestock are routinely given low dose ionophore antibiotics in their feed. This reduces methane directly and boosts productivity so fewer animals are needed for the same output, but it is illegal in the EU because of fears that it will contribute to antibiotic resistance, with knock-on effects for human health. Such dilemmas are a taster of the difficult questions ahead for farmers and society.

Agriculture enjoys a light-touch regime of voluntary action on greenhouse gas emissions, but government may intervene more forcefully after a promised review in 2012. An industry ‘delivery plan’ to be finalised this autumn will set out in more detail an agreed monitoring framework to judge success.Greenhouse gas emissions from Agriculture

The second annual progress-checking report from the government’s advisory Committee on Climate Change (CCC) published in July notes the current voluntary regime for farming is unusual compared to most other sectors of the economy. “It is highly likely that in future alternative policy measures will be required,” the committee argues.2

Uncertainty reigns over potential for mitigation

The environment department’s (DEFRA’s) climate change plan, published in March, sets out how the sectors it covers can contribute to meeting UK greenhouse gas reductions targets.3  For farming emissions, it outlined three main options for moving beyond voluntary action.

The first would build on existing regulation such as the Nitrates Directive and the Water Framework Directive. Nitrate Vulnerable Zones (NVZs) limit the amount of manure or fertiliser that can be spread per hectare to prevent run-off and water pollution. There are co-benefits for greenhouse gas mitigation, which could be enhanced by tightening restrictions or designating additional areas, although NVZs already cover 62% of England and are deeply unpopular with farmers.

The second option would be new regulation. The Pollution Prevention and Control Act 1999 confers powers sufficient to define mandatory best practice for farm abatement, for instance. Lastly, the plan mentions the possibility of economic incentives to reward farmers for abatement action.

But all of this was written pre-election; details of the new government’s approach will be set out in October in its response to the CCC’s July report. With the government’s Task Force on Farm Regulation looking for ways to cut red tape for agriculture and due to report early next year, a ‘big government’ solution seems unlikely. Voluntary, industry-led action “remains the preferred option,” says a DEFRA spokesman.

But the CCC warns “there is a risk that the chosen approach will not deliver the full emissions reduction potential available”. It adds that the 3MtCO2e/year target for England “appears low” compared with what could be achieved. The farming industry does not agree. Its action plan calls the target “very challenging” and says it will be “close to the limits of what is feasible”.

The CCC’s assertions are based on marginal abatement cost curves (MACCs) for farming drawn up by the Scottish Agricultural College (SAC). MACCs compare the cost and mitigation potential of different mitigation options. This work suggests agriculture could deliver “between five and 12MtCO2e per annum technical emissions reduction potential in 2020” at a price below £40 per tonne of carbon saved. The 3MtCO2e target for England scales up to about 4.5MtCO2e at UK level so is roughly comparable with the most pessimistic analysis from SAC, but far below the 12MtCO2e top end.

Dominic Moran, SAC agricultural economist and one of the authors of the MACC, freely acknowledges the uncertainties around some mitigation options, where the science base is relatively limited and information on their effectiveness is somewhat anecdotal. Question marks include the amount of land available for each intervention and the timing of new policies. The future direction of the EU Common Agricultural Policy which is currently under review, is a key unknown (see box).

“There is still a lot of uncertainty about the abatement potential,” says Bob Rees, a colleague at SAC. There are plenty of farm-scale case studies but it is difficult to scale these up to a national level, Dr Rees explains.

The potential for mitigation through improved land drainage seems to be particularly uncertain. Wet agricultural land has higher N2O emissions because it favours the bacteria responsible for these.

Grants used to be available to improve drainage on farms but maintenance may have slipped since grants stopped, says Dr Rees. It is hard to be sure, as survey data are limited. On the other hand, pressure to recreate wetlands for flood protection and biodiversity might reduce N2O emissions and increase carbon sequestration if the land is no longer farmed.

The gains to be had through improved ruminant diets are also speculative. There is considerable variation in methane emissions both between individual animals and according to breed, says animal nutritionist Dr Moorby. “We just don’t have the measurements we need” to know the level of abatement possible, he says.

Organic farming certifiers the Soil Association often point to the ground beneath our feet and the carbon it stores as an underappreciated target for farm greenhouse mitigation. It says organic farming is the most climate-friendly if you take soil carbon into account (ENDS Report 416, p 23).

The evidence, though, is thin. Farming methods that plough the soil less often or not at all are thought to increase soil carbon, but it is not clear if the benefits continue to accrue year after year. Neither is it known what reduced tillage does to N2O emissions; an increase could cancel out any climate benefit. But research has found both increases and decreases depending on conditions, says soil microbiologist Ute Skiba at the Natural Environment Research Council Centre for Ecology and Hydrology’s Edinburgh laboratory.

The easiest way to mitigate soil N2O, she says, is to mix chemicals known as nitrification inhibitors with fertiliser and manures before spreading on fields. They have been around for decades, but remain unused because of cost. Research in New Zealand suggests they can cut N2O emissions from soil by up to 90%. A £2.5m DEFRA-funded project to assess their potential in England and Wales should be completed by 2014. It will collect data across different soil and input types, explains ADAS’s Professor Chambers, another project partner. Related research will focus on trying to better understand how soil type, climate and farm management affect N2O emissions.

Methane tent, Jon MoorbyAt the heart of attempts to address agricultural greenhouse gases is a glaring hole where accurate measurement of emissions ought to be. Broadly speaking the emissions inventory as it stands depends on only two things, namely the amount of fertiliser applied to land and the number of livestock.

The calculation for N2O is likened by Professor Chambers to a “blunderbuss” approach. First, take the total area of farmland and multiply by the average rate of fertiliser application. Then simply assume 1% of the nitrogen added will be emitted as N2O.

There are several big problems with this. According to Dr Rees at SAC, some farming areas with high rainfall are known to have much higher rates, with maybe 7–8% of nitrogen applied being emitted as N2O. We cannot be sure, but the 1% average could still be reasonable on a nationwide basis because dry eastern areas probably have lower emissions, says Dr Rees.

More worryingly for farmers, the current inventory will be blind to many of the measures proposed to cut their emissions. Improvements in the timing or accuracy of fertiliser application would go unnoticed unless they coincidentally reduce overall usage. Similarly for livestock, changes in diet would be invisible says Dr Moorby. “At the moment the emissions inventory only really notices the number of animals.”

DEFRA had committed to improving the inventory so it could record the impact of improved farm management on emissions. Before the election, the first phase of this had been scheduled for completion by 2014. ENDS understands that a major £12m research grant towards a smarter inventory was agreed at ministerial level in mid-September, following concerns that budget cuts might have affected funding. But the precise specifications for research are thought to be under negotiation and no contracts have been signed. A DEFRA spokesman said it was too soon to confirm any details.

Farming industry inching forward

The work is likely to be in three strands: N2O from soils, methane from ruminants and an overarching project to draw these results into the inventory. Improvements are “absolutely crucial” says NFU’s Dr Jones, because otherwise changes to farm management will not be rewarded. Meanwhile, scepticism remains over the long-term level of climate mitigation agriculture can achieve. CLA’s Professor Buckwell says: “We don’t doubt there are gains to be had but if we could do it easily we would be doing it already.”

The CCC’s July report also noted many possibilities for abatement should have been taken up by farmers by now because they are supposed to save money. That is why CCC argued that voluntary, industry-led information provision may be insufficient to overcome barriers to implementation.

Yet the scale of change needed by 2020 alone is daunting. Even to achieve the low end of abatement potential projected by CCC, milk yield per cow would need to improve by up to 50% and beef yield by up to 15%. Ever-increasing outputs per animal cannot go on forever. Parts of the livestock industry are “already coming up against basic laws of nature,” says Donal Murphy-Bokern, a farming consultant and former DEFRA civil servant.

Since the CCC is working on the assumption that non-CO2 emissions will fall 70% by 2050, and since agriculture today makes up 45% of this non-CO2 total, the CCC says “more significant emissions reduction from agriculture beyond 2020 will be required”. There are very few clear ideas about how such massive levels of reduction might be achieved. “Efficiency can only take you so far,” says Dr Rees at SAC.

The work on MACCs done by SAC suggests that up to 12MtCO2e a year could be saved at a cost of £40 per tonne of CO2, using available technology and techniques. That would be a major step along the way to making those big cuts.

But of course farmers are not charged £40/t CO2e emitted, neither are they likely to be in the foreseeable future. Even if they were not all of them would actually choose to make the emission savings. And the scope for change through future technical improvement is “likely to be marginal rather than revolutionary,” says Dr Murphy-Bokern. Talk of step changes in emissions, for instance methane mitigation through diet is “highly speculative,” he says. Or as Professor Chambers puts it: “Stopping ruminants ruminating would be quite an achievement.”

Getting beyond marginal improvements means more radical change to the way farming operates, Dr Murphy-Bokern argues. For instance, if livestock and crop farming were reintegrated in mixed farms, nutrients might be better retained in the agricultural system. The UK is actually quite well placed to go back to mixed farms, he says, because the livestock and arable sectors are not as spatially separated as they are on the continent.

And then there is the human diet. “You simply have to look at the demand side,” says Dr Murphy-Bokern. “There’s huge potential through changes in the food we eat.”

Livestock products contribute about two thirds of food-related greenhouse gas emissions but only one third of the calories we eat. The soon-to-be defunct Sustainable Development Commission was one of many organisations to suggest lowering meat and dairy consumption would reduce the environmental impacts of diet (ENDS Report 420, pp 40–42). NFU’s Dr Jones says it will be interesting to see the new government’s approach to the “very sensitive” question of diet. “Although the way that farmers farm can make a contribution, everyone else has to play their part,” she says.

In its recipe for a zero-carbon UK by 2030, the Centre for Alternative Technology said agricultural emissions could be slashed to a fifth of current levels, largely by switching towards a vegetarian diet and growing large amounts of bioenergy crops (ENDS Report 425, p 19). A somewhat less radical option is offered by the Centre
for Ecology and Hydrology’s Dr Skiba. Along with 231 other European and US scientists, she has signed up to the Barsac
Declaration, a commitment to a ‘demitarian’ diet containing half as much animal protein as normal.4

Drastic shifts in demand for livestock products could free huge tracts of the nation’s farmland for other uses, perhaps bioenergy crops, forestry or nature conservation. A common refrain from farmers is that uplands are suitable only for livestock. An end to grazing would risk losing the character of habitats prized for their landscape and recreational value. “There’s an idea that this semi-natural pasture is an environmental good compared with natural vegetation, but where’s the evidence?” asks Dr Murphy-Bokern. In most of continental Europe equivalent areas are wooded.

Five radical scenarios for the future of Welsh farming to 2050 were drawn up for the Assembly Government in March.5  These included massive increases in the area given over to forestry and even a move to exclusively indoor dairy farming where emissions of all kinds would be easier to capture. The reaction to this sort of idea can be gauged by events in March, when a proposed ‘super dairy’ of 8,100 cows at Nocton in Lincolnshire drew an outpouring of opprobrium. The plans would have seen cows housed mainly indoors with slurry treated in a 2MW AD plant. The developers have since withdrawn the plan but intend to submit a new application after addressing technical issues.

By the end of 2010, the CCC will publish its advice on the UK’s fourth carbon budget covering 2023–2027, when emissions cuts for agriculture will really begin to bite. The CCC has promised to consider the scope for achieving emissions reductions through both demand- and supply-side measures. Although it has been critical of the 2020 target for England of just 3MtCO2e, the CCC has acknowledged the industry-led approach is “a useful first step to engage the sector”.

NFU’s Dr Jones makes clear that the action plan as it stands is “only a start”. Perhaps this is the best we could have hoped for. Dr Moran concludes: “the farming industry is moving in the right direction and that’s all anyone ever wanted them to do.”