̽��ֱ�� of Cambridge - farming

Transition Live: Park Farm

plc32 — Tue, 14 May 2024 14:18:35 +0000

̽��ֱ�� of Cambridge's Park Farm hosted one of the most important new agricultural events on the UK farming calendar this month.

Carbon emissions from fertilisers could be reduced by as much as 80% by 2050

sc604 — Thu, 09 Feb 2023 15:48:50 +0000

̽��ֱ��researchers, from the ̽��ֱ�� of Cambridge, found that two-thirds of emissions from fertilisers take place after they are spread on fields, with one-third of emissions coming from production processes.

Although nitrogen-based fertilisers are already known to be a major source of greenhouse gas emissions, this is the first time that their overall contribution, from production to deployment, has been fully quantified. Their analysis found that manure and synthetic fertilisers emit the equivalent of 2.6 gigatonnes of carbon per year – more than global aviation and shipping combined.

Carbon emissions from fertilisers urgently need to be reduced; however, this must be balanced against the need for global food security. Earlier research has estimated that 48% of the global population is fed with crops grown with synthetic fertilisers, and the world’s population is expected to grow by 20% by 2050.

̽��ֱ��Cambridge researchers say that a combination of scalable technological and policy solutions are needed to reduce fertiliser emissions while maintaining food security. However, they estimate that if such solutions could be implemented at scale, the emissions from manure and synthetic fertilisers could be reduced by as much as 80%, to one-fifth of current levels, without a loss of productivity. Their results are reported in the journal Nature Food.

“Incredibly, we don’t actually know how many chemicals we produce globally, where they end up, where and how they accumulate, how many emissions they produce, and how much waste they generate,” said co-author Dr André Cabrera Serrenho from Cambridge’s Department of Engineering.

Serrenho and his co-author Yunhu Gao undertook a project to accurately measure the total impacts of fertilisers, one of the two main products of the petrochemical industry. Of all the products made by the petrochemical industry, the vast majority – as much as 74% – are either plastics or fertilisers.

“In order to reduce emissions, it’s important for us to identify and prioritise any interventions we can make to make fertilisers less harmful to the environment,” said Serrenho. “But if we’re going to do that, we first need to have a clear picture of the whole lifecycle of these products. It sounds obvious, but we actually know very little about these things.”

̽��ֱ��researchers mapped the global flows of manure and synthetic fertilisers and their emissions for 2019, along all stages of the lifecycle, by reconciling the production and consumption of nitrogen fertilisers and regional emission factors across nine world regions.

After completing their analysis, the researchers found that unlike many other products, the majority of emissions for fertilisers occur not during production, but during their use.

“It was surprising that this was the major source of emissions,” said Serrenho. “But only after quantifying all emissions, at every point of the lifecycle, can we then start looking at different mitigation methods to reduce emissions without a loss of productivity.”

̽��ֱ��researchers listed and quantified the maximum theoretical impact of different mitigation methods – most of these are already known, but their maximum potential effect had not been quantified.

Emissions from the production of synthetic fertilisers are mostly from ammonia synthesis, partly due to chemical reactions used in the production process. ̽��ֱ��most effective mitigation at the production stage would be for the industry to decarbonise heating and hydrogen production. Additionally, fertilisers could be mixed with chemicals called nitrification inhibitors, which prevent bacteria from forming nitrous oxide. However, these chemicals are likely to make fertilisers more expensive.

“If we’re going to make fertilisers more expensive, then there needs to be some sort of financial incentive to farmers and to fertiliser companies,” said Serrenho. “Farming is an incredibly tough business as it is, and farmers aren’t currently rewarded for producing lower emissions.”

̽��ֱ��single most effective way to reduce fertiliser-associated emissions, however, would be to reduce the amount of fertilisers that we use. “We’re incredibly inefficient in our use of fertilisers,” said Serrenho. “We’re using far more than we need, which is economically inefficient and that’s down to farming practices. If we used fertiliser more efficiently, we would need substantially less fertiliser, which would reduce emissions without affecting crop productivity.”

̽��ֱ��researchers also looked at the mix of fertilisers used around the world, which varies by region. ̽��ֱ��researchers say that replacing some of the fertilisers with the highest emissions, such as urea, with ammonium nitrate worldwide could further reduce emissions by between 20% and 30%. However, this would only be beneficial after decarbonising the fertiliser industry.

“There are no perfect solutions,” said Serrenho. “We need to rethink how we produce food, and what sorts of economic incentives work best. Perhaps that means paying farmers to produce fewer emissions, perhaps that means paying more for food. We need to find the right mix of financial, technological and policy solutions to reduce emissions while keeping the world fed.”

Serrenho and Gao estimate that by implementing all the mitigations they analysed, emissions from the fertiliser sector could be reduced by as much as 80% by 2050.

“Our work gives us a good idea of what’s technically possible, what’s big, and where interventions would be meaningful – it’s important that we aim interventions at what matters the most, in order to make fast and meaningful progress in reducing emissions,” said Serrenho.

̽��ֱ��research was part of the C-THRU project, led by Professor Jonathan Cullen, where researchers from four UK and US Universities are working to bring clarity to the emissions from the global petrochemical supply chain.

Reference:
Yunhu Gao and André Cabrera Serrenho. ‘Greenhouse gas emissions from nitrogen fertilisers could be reduce by up to one-fifth of current levels by 2050 with combined interventions.’ Nature Food (2023). DOI: 10.1038/s43016-023-00698-w

Researchers have calculated the carbon footprint for the full life cycle of fertilisers, which are responsible for approximately five percent of total greenhouse gas emissions – the first time this has been accurately quantified – and found that carbon emissions could be reduced to one-fifth of current levels by 2050.

Our work gives us a good idea of what’s technically possible, and where interventions would be meaningful – it’s important that we aim interventions at what matters the most, in order to make fast and meaningful progress in reducing emissions

André Cabrera Serrenho

SteveAllenPhoto via Getty Images

Spraying fertiliser on wheat crop - North Yorkshire - England.

̽��ֱ��text in this work is licensed under a Creative Commons Attribution 4.0 International License. Images, including our videos, are Copyright © ̽��ֱ�� of Cambridge and licensors/contributors as identified. All rights reserved. We make our image and video content available in a number of ways – as here, on our main website under its Terms and conditions, and on a range of channels including social media that permit your use and sharing of our content under their respective Terms.

Yes

Paying farmers to create woodland and wetland is the most cost-effective way to hit UK environment targets

fpjl2 — Tue, 20 Dec 2022 09:58:28 +0000

Incentivising farmers to restore some land as habitats for nature could deliver UK climate and biodiversity targets at half the taxpayer cost of integrating nature into land managed for food production, according to a new study published today in the British Ecological Society journal People and Nature.

̽��ֱ��research, led by the universities of Cambridge, Leeds and Glasgow, provides the first evidence for the taxpayer savings offered by focusing food production in certain areas to allow the creation of new woods, wetland and scrub habitats on some of the land currently used for farming.

̽��ֱ��study suggests that this 'land sparing' approach would cost just 48% of the funds required to achieve the same outcomes for biodiversity and the climate through an approach known as 'land sharing', where conservation measures get mixed into farming by adding hedgerows to fields, reducing pesticides, and so on – all of which lowers food yield.

Additionally, researchers say that trying to share land with nature through making farming more wildlife-friendly would see the UK lose 30% more of its food production capacity than if farmers are encouraged to spare portions of land entirely for creating semi-natural habitats.

̽��ֱ��UK Government has legally binding commitments to reverse nature declines by 2030 and reach net-zero carbon by 2050. Sparing land for habitats could hit these targets at half the cost of trying to farm on land shared with nature, say researchers.

“Currently, only a fraction of the £3.2 billion of public money annually paid to farmers goes on biodiversity and climate mitigation, some £600m a year,” said Lydia Collas, who led the study as part of her PhD at Cambridge ̽��ֱ��’s Department of Zoology.

“Almost all this fraction of funding supports land-sharing approaches that may do little to benefit species or sequester carbon, but do typically reduce food yields. Until now there has been no research on whether this is the most cost-effective solution to delivering environmental targets.”

Cambridge’s Prof Andrew Balmford, senior author of the study, said: “Greater incentives for farmers to create woodlands and wetlands will deliver for wild species and climate mitigation at half the cost to the taxpayer of the land-sharing approach that currently receives ten times more public funding.”

̽��ֱ��researchers say their findings – presented at the British Ecological Society’s annual meeting by study co-author Prof Nick Hanley, an environmental economist from the ̽��ֱ�� of Glasgow – should inform the current Brexit-prompted rethink of England’s new Environmental Land Management Scheme (ELMs).

̽��ֱ��Landscape Recovery strand of the ELM is set to receive under 1% of the overall budget next year – a dramatic underspend considering the economic, environmental and food security benefits of a habitat creation approach, argue the scientists.

They say that the revamped Countryside Stewardship Scheme would also deliver far better value for money if it supports farmers to create habitats for nature instead of repeating the largely 'wildlife-friendly' approach of the scheme in its current form.

“If a two-fold cost saving was identified in other government policy areas, such as health, there would be an outcry,” said Collas, “particularly in the face of the worst recession in a generation.”

̽��ֱ��researchers conducted a choice experiment study with 118 farmers responsible for 1.7% of all England’s arable land, asking them to estimate the payments they would require to implement land-sharing practices or habitat-creating 'sparing' approaches on their land.

Farmers chose from a variety of agricultural approaches, nature interventions and, crucially, payment rates. ̽��ֱ��study also considered the government's costs of administering and monitoring these schemes.

̽��ֱ��team used three bird species – yellowhammers, bullfinches and lapwings – as a proxy for effects on biodiversity, as well a range of ways farmers could help slow climate change, such as woodland and hedgerow creation.

On average, farmers in the experiment accepted lower payments per hectare for land sharing practices. However, habitat creation schemes deliver far greater environmental outcomes per hectare, so creating woodlands, wetlands and scrublands would deliver the same overall biodiversity and climate mitigation benefits at half the cost to the taxpayer.

“We found that enough farmers are willing to substantially change their business to benefit from payments for public goods in the form of habitats, provided the government rewards them properly for doing so,” said Balmford.

Collas, now a Policy Analyst at Green Alliance, added: “Existing evidence already shows that semi-natural habitats deliver far more biodiversity and climate mitigation per unit area, and creating them has far less impact on food production than meeting targets through land sharing.

“This evidence is dismissed when thinking about agricultural policy in the UK because of an untested assumption that farmers are unwilling to create natural habitat. We now have evidence showing this assumption is wrong.”

Study of farmer preferences shows that turning whole areas of farmland into habitats comes with half the price tag of integrating nature into productive farmland, if biodiversity and carbon targets are to be met.

Semi-natural habitats deliver far more biodiversity and climate mitigation per unit area

Lydia Collas

Getty images

Drone view of agricultural field - a tractor is baling hay next to woodland

Yes

̽��ֱ��future of farming: from eating insects to urban agriculture

sc604 — Wed, 07 Dec 2022 12:50:38 +0000

̽��ֱ��Entrepreneurship Centre at Cambridge Judge Business School is supporting new ventures to improve sustainability in agriculture to meet the demands of a growing global population.  

Intensive farming may actually reduce risk of pandemics, experts argue

cg605 — Fri, 24 Jun 2022 13:18:00 +0000

In the wake of COVID-19, many have pointed to modern industrial farms with tightly-packed livestock as potential hothouses for further pandemics caused by 'zoonotic' diseases: those transmitted from animals to humans.

However, researchers now argue that free-range alternatives, which require far more land, would increase encroachment on natural habitats and create ever more potential for diseases carried by wild animals to come into contact with humans and jump the species barrier.

In a paper in Royal Society Open Science, a team of scientists led by Cambridge ̽��ֱ�� found a lack of sufficient evidence to conclude which way of farming is least risky, and say there is evidence that the move away from intensive farming might actually increase the risk of pandemics. They call for more research to be done before changing policies or incentivising a particular type of farming.

"High-yield or ‘intensive’ livestock farming is blamed for pandemics, but those calling for a move away from intensive farming often fail to consider the counterfactual – the pandemic risk of farming less intensively and particularly the consequences for land use,” said lead author Harriet Bartlett, a PhD candidate at Cambridge's Department of Zoology.

“Low-yield farms need far more land to produce the same amount of food compared with high-yield farms. A widespread switch to low-yield farming would result in the destruction and disturbance of vast areas of natural habitats. This increases the risk of viral spillover by disturbing wildlife that may well host the next pandemic virus and increasing contact between wildlife, people and livestock," Bartlett said.

̽��ֱ��researchers point out that, globally, we now produce four times more meat than we did in the 1960s. Most of our meat, eggs and dairy now come from intensive farms, but such farms are thought be risky due to their crowded conditions which increase the chance of diseases ‘taking off’ and spreading rapidly.

However, intensive farms need less land than extensive, or ‘free-range’, farms to produce the same amount of food – both to grow their feed and to rear their animals.

Growing demand for livestock products has caused dramatic habitat loss, say the researchers, which means we are now farming in places where livestock and people are coming into frequent contact with wildlife. They say that this contact with increasingly disturbed, stressed, and infected wildlife makes the spillover of zoonotic viruses into people or livestock more likely.

"If we were to switch from the current system to one based on extensive farming, we would need substantially more land to meet demand – resulting in the conversion of habitat roughly the size of Brazil and India between 2009 and 2050," said paper co-author Prof Andrew Balmford. "This could increase the contact between people, livestock and stressed wildlife – including wildlife that might well host the next pandemic virus."

"Intensive farms may have a greater risk of takeoff, but extensive farms may have greater risk of spillover," he said.

̽��ֱ��researchers say that, worryingly, we simply do not know which risk is more important for preventing future pandemics, and so it is currently impossible to determine which types of farms carry least risk overall.

Added Bartlett: "COVID-19 has demonstrated the huge potential impact of zoonotic diseases, and this study highlights that more research is urgently needed to identify how we minimise the risk of another pandemic."

Reference:

Bartlett H, Holmes MA, Petrovan SO, Williams DR, Wood JLN, Balmford A. 2022 Understanding the relative risks of zoonosis emergence under contrasting approaches to meeting livestock product demand. R. Soc. Open Sci. 9: 211573. https://doi.org/10.1098/rsos.211573

Scientists evaluate the evidence that intensive livestock farming is causing pandemics, and find that intensive farming could actually reduce the risk of future pandemics compared to 'free-range' farming.

Those calling for a move away from intensive farming often fail to consider the counterfactual

Harriet Bartlett

Getty images

Portrait of young woman farmer holding fresh eggs in hands

Yes

Reducing the rise of antibiotic resistance

lw355 — Mon, 22 Nov 2021 12:00:01 +0000

Rising resistance to antibiotics is a worrying prospect, but a success story happening across the farms of the UK gives hope that something can be done.

Growing Underground

lw355 — Mon, 29 Mar 2021 08:00:00 +0000

In the heart of London there is a farm like no other. It's subterranean, sustainable and energy smart. It also has a digital twin looking out for its every need.

Cost and scale of field trials for bovine TB vaccine may make them unfeasible

cjb250 — Thu, 07 Jun 2018 10:50:07 +0000

Instead, the researchers suggest that the scale and cost of estimating the effect of a vaccine on transmission could be dramatically reduced by using smaller, less expensive experiments in controlled settings – using as few as 200 animals.

Bovine TB is an infectious disease that affects livestock and wildlife in many parts of the world. In the UK, it is largely spread between infected cattle; badgers are also involved, transmitting to and receiving infection from cattle. Culls to keep badger populations small and reduce the likelihood of infecting cattle have proven controversial both with the public and among scientists.

̽��ֱ��UK has a policy of ‘test and slaughter’ using the tuberculin test and slaughter of infected animals. A vaccine (BCG) exists, but can cause some vaccinated cattle to test positive falsely. As such, the vaccine is currently illegal in Europe. Researchers are trying to develop a so-called ‘DIVA test’ (‘Differentiates Infected from Vaccinated Animals’) that minimises the number of false positives, but none are yet licensed for use in the UK.

̽��ֱ��European Union has said it would consider relaxing its laws against bovine TB vaccination if the UK government were able to prove that a vaccine is effective on farms. Any field trials would need to follow requirements set by the European Food Safety Authority (EFSA).

In research published today, a team of researchers led by the ̽��ֱ�� of Cambridge has shown using mathematical modelling that satisfying two key EFSA requirements would have profound implications for the likely benefits and necessary scale of any field trials.

̽��ֱ��first of these requirements is that vaccination must be used only as a supplement, rather than replacement, to the existing test-and-slaughter policy. But use of vaccination as a supplement means that a successful vaccine which reduces the overall burden and transmission of disease may nonetheless provide only limited benefit for farmers – false positives could still result in animals being slaughtered and restrictions being placed on a farm.

̽��ֱ��second of the EFSA requirements is that field trials must demonstrate the impact of vaccination on transmission rather than just protecting individual animals.

̽��ֱ��team’s models suggest that a three year trial with 100 herds should provide sufficient to demonstrate that vaccination protects individual cattle. Such a trial would be viable within the UK. However, demonstrating the impact on vaccination on transmission would be almost impossible because the spread of bovine TB in the UK is slow and unpredictable.

If BCG were to be licensed for use in cattle in the UK, vaccination would be at the discretion of individual farmers. Farmers would have to bear the costs of vaccination and testing, as well as the period of time under restrictions if animals test positive. This means that they would be less interested in the benefit to individual cattle and more interested in the benefits at the herd level. Herd immunity is such that, even if the vaccine is not 100% effective in every individual animal, the vaccine has an overall protective effect on the herd.

Trying to demonstrate an economic benefit for farmers would prove challenging. Using their models, the researchers show that herd-level effectiveness would be exceptionally difficult to estimate from partially-vaccinated herds, requiring a sample size in excess of 2,000 herds. ̽��ֱ��number of herds required could be reduced by a ‘three arm design’ that includes fully-vaccinated, partially-vaccinated and unvaccinated control herds; however, such a design would still require around 500 fully-vaccinated herds and controls – presenting potential logistical and financial barriers – yet would still have a high risk of failure.

Instead, the researchers propose a natural transmission experiment involving housing a mixture of vaccinated and unvaccinated cattle with a number of infected cattle. Such an experiment, they argue, could provide robust evaluation of both the efficacy and mode of action of vaccination using as few as 200 animals. This would help screen any prospective vaccines before larger, more expensive and otherwise riskier trials in the field.

“We already know that the BCG vaccine has the potential to protect cattle from bovine TB infection,” says Dr Andrew Conlan from the Department of Veterinary Medicine at the ̽��ֱ�� of Cambridge, the study’s first author. “Our results highlight the enormous scale of trials that would be necessary to evaluate BCG alongside continuing testing in the field.

“Such trials would be hugely expensive, and it isn’t even clear whether enough farms could be recruited. This scale could be dramatically reduced by using smaller scale natural transmission studies.”

Based on current knowledge of the likely efficacy of BCG, the researchers say their models do not predict a substantial benefit of vaccination at the herd level when used as a supplement to ongoing test-and-slaughter. Ruling out the use of vaccination as a replacement, rather than a supplement, to test-and-slaughter will inevitably limit the effectiveness and perceived benefits for farmers.

“If we could consider replacing test-and-slaughter with vaccination, then the economics becomes much more attractive, particularly those in lower income countries,” says Professor James Wood, Head of Cambridge’s Department of Veterinary Medicine. “Then, we would no longer need to carry out expensive testing, but could instead rely on passive surveillance through the slaughterhouses.”

̽��ֱ��study was funded by the UK Department for Environment, Food and Rural Affairs (Defra) and the Alborada Trust

Reference
Conlan, AJK, et al. ̽��ֱ��intractable challenge of evaluating cattle vaccination as a control for bovine Tuberculosis. eLife; 5 June 2018; DOI: 10.7554/eLife.27694.001

Field trials for a vaccine to protect cattle against bovine tuberculosis (bovine TB) would need to involve 500 herds – potentially as many as 75,000-100,000 cattle – to demonstrate cost effectiveness for farmers, concludes a study published today in the journal eLife.

Our results highlight the enormous scale of trials that would be necessary to evaluate BCG alongside continuing testing in the field. Such trials would be hugely expensive, and it isn’t even clear whether enough farms could be recruited

Andrew Conlan

Knarrhultpia

Curious cows

Researcher Profile: Dr Andrew Conlan

It may seem surprising to find a physicist in the Department of Veterinary Medicine, but this was how Dr Andrew Conlan began his career at the ̽��ֱ�� of Edinburgh. He is now an applied mathematician and statistician at in Cambridge’s Disease Dynamics Unit, engaged in work which he describes as “intensively multi-disciplinary”, requiring him to work within multiple environments with medics, veterinarians, farmers, policymakers – and even school children.

Andrew’s research sets out to use mathematics to predict the spread of infectious disease within populations and provide evidence to inform policy on the control of infectious diseases in humans and animals. His work centres around controlling the spread of diseases such as bovine TB and human diseases including, measles, whooping cough, scarlet fever, norovirus and meningitis.

“Policy decisions on the control of infectious diseases often have to be made quickly based on limited information and data,” he says. “I believe that government policy on infectious disease control should be based on evidence and good science.”

Although much of his research is office-based, involving analysing data, writing computational models and occasionally pen-and-paper work, he also does a lot of work with schools, working with pupils on research projects and delivering lessons on disease transmission.

“I’ve been involved in running citizen science projects for many years now, which have led to several peer reviewed papers on how social contact networks in schools could be useful to predict the spread of infectious disease,” he explains (while, ironically, nursing a cold picked up from his son, who had in turn picked it up at nursery). “I dreamed it up over a tea break with my colleague Ken Eames. At the time very little work had been down on contact patterns in school age children as they are a potentially vulnerable population that is difficult to access. We thought that getting them to do the research themselves and take ownership would be a way to address it – and it worked!”

Yes

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