Food for thought - fostering sustainable agriculture

3rd August 2023

Food for thought

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Rick Gould

Rick Gould investigates how transforming our diets can foster sustainable agriculture

In 1923, Cecile Steele from the Delmarva Peninsula, US, ordered 50 chicks from a local hatchery to raise a few dozen hens for eggs and meat. However, the delivery driver brought her 500 due to an error.

Unable to return them, she adapted and is reputed to have started the modern industry of intensive chicken farming. She bought 1,000 chicks the next year, 10,000 two years later, and kept growing her business. Many other farmers copied her.

Chickens, however, are picky eaters and, like many other intensively farmed animals, require crop-based feed, which in turn needs lots of land and fertiliser to grow. Fertiliser availability was once a limiting factor but, in 1913, BASF in Germany started making enormous amounts of ammonia from nitrogen in the air, using the novel Haber-Bosch process. Ammonia is a key building block of chemical fertilisers and provides reactive nitrogen, essential for plant and animal proteins.

The techniques developed by Steele, animal breeders and industrial chemists have had far-reaching impacts; without them, the world’s population is likely to have been around half of what it is now, and far fewer people would enjoy a diet rich in meat and dairy products, largely propelled by chemical fertiliser.

So how big has this growth been, and what are the specific impacts?

Growth in meat and dairy

The chemical industry makes more than 100 million tonnes of fertiliser annually, eight times as much as in 1960. The world now produces more than three times as much meat as it did 50 years ago. Currently, about 80 billion farm animals are slaughtered annually to produce almost 350 million tonnes of meat.

According to the UN Food and Agriculture Organization, poultry is a dominant form of meat.

Feeding the world’s population means that almost half of all habitable land is used for agriculture and 80% of that is used for growing animal feed for the billions of animals whose emissions of a carbon compound and greenhouse gas, methane, get a lot of attention. However, carbon’s neighbour on the periodic table, nitrogen, gets much less attention, even though excess environmental nitrogen has serious effects. For example, emissions of ammonia from animal manure, slurry and fertilisers are an increasing problem globally. Wales and England’s Wye Valley typifies the problems.

No longer ignoring nitrogen

“While the majority of air pollutants have shown marked declines, ammonia emissions have bucked this trend,” says Simon Bareham, principal adviser on air quality and biodiversity for National Resources Wales (NRW), who has more than 30 years’ experience in this area, and has seen decreases in biodiversity due to ammonia emissions.

“More than half of the Welsh land area now exceeds the ammonia air-quality thresholds established to protect sensitive ecosystems,” he adds. “The intensive rearing of poultry, mostly chicken, has led to significant degradation of the Welsh aquatic and terrestrial environment. The situation has grown worse in recent years as consumers opt for leaner, white meat and free-range eggs.”

Counter-intuitively, free-range farming has higher emissions of ammonia than equivalent-sized intensive farms, where animals are raised indoors and emissions from manure are easier to control.

Additionally, NRW regulates the larger intensive farms, and has strict controls on ammonia emissions. “Ironically, it is the smaller free-range units not regulated by NRW that have the most profound impacts in parts of Wales,” says Bareham.

There are also few controls on manure spreading from such farms, which leads to runoff into rivers and eutrophication. “While public awareness of ammonia air pollution remains very low, the issue of poultry units and waste spreading has been highlighted in the very high-profile issues of ongoing acute pollution of the River Wye.”

So, what are the answers to these problems? Bareham says: “Controlling ammonia emissions from spreading manure and slurry is relatively easy. Also, air filters on animal housing, covering slurry and manure stores, and low-emission spreading techniques are all readily available but are seldom applied. This is not rocket science, but more the political willingness to make such measures mandatory.” However, technology can only go so far.

A complex reality

“It is too risky to say that technology will solve the problems we have today and that we don’t need to change behaviour,” says Dr Hannah van Zanten, associate professor at Wageningen University in the Netherlands. “For example, people can believe they do not need to change their diets because technology will make our diets sustainable. The reality is much more complex and nuanced.”

Van Zanten’s team and researchers elsewhere have been examining three interrelated themes: repurposing animal feed, dietary changes and circularity.

Many researchers have examined the benefits of repurposing land used for growing animal feed. One international team of researchers focused on the US, where 75% of soya beans are grown to feed animals. The researchers determined that if the land area used to grow feed for beef were used for growing poultry feed, it would be possible to feed up to an extra 140 million people. And if the same land area were used to grow crops for a proportionately higher plant-based diet, it could feed an extra 190 million people.

Van Zanten was also part of another international team of researchers that examined soya beans fed to animals.
The EU is heavily dependent on soya imports, yet the researchers found that this could be reduced by about 80% through measures such as dietary changes, like a diet with more legumes and soya-bean products.

This in turn would free up up to 14 million hectares of land outside the EU, currently used to grow soya beans. The common factor between these studies and others like them is a switch from red meat and poultry products to more plant proteins such as legumes and pulses.

“The main reduction takes place in beef. If we consume the same amount of red meat and apply circulatory principles, then we replace beef with pork or slaughtered dairy cattle. Excluding grass-fed dairy cattle, pigs can eat food waste and parts of crops we cannot eat,” explains van Zanten.

Van Zanten’s team is now looking at a significant redesign of the food system, focusing on circularity, repurposing and alternative protein sources. The team has developed a model called Circular Food Systems (CiFoS), allowing people to design and assess achievable, innovative and sustainable food systems.

“We developed the CiFoS model to look at different, optimised scenarios to provide a healthy diet, with reduced environmental impacts. The model tells us, for example, which crops to grow where, and which fertilisers to use under different scenarios,” explains van Zanten.

“The [CiFoS] model tells us which crops to grow where, and which fertilisers to use under different scenarios”

Changes in consumption

So, what reductions or changes in meat and dairy consumption should we expect? “It depends on the scenario, such as whether we include importing and exporting. Although there are reductions in animal products in diets, milk is reduced least. For example, if you feed grass-fed cattle with crop by-products, then they are efficient animals,” she adds.

Both van Zanten’s team and other international researchers are also looking at fertilisers, such as minimising chemical fertilisers, while using organic fertiliser efficiently and sustainably.

Lastly, researchers at Wageningen and many other centres are often asked if technology can enable us to continue with our current diet. “No, that is simple to answer. It is not good for us and not good for the planet,” she concludes. In short, sustainable agriculture means a paradigm shift in our diet.

Rick Gould is an air-quality adviser at the Environment Agency. He writes in a personal capacity


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