From international calls to limit livestock emissions, to industry-led efforts to cut antibiotic use, the challenge of creating more sustainable pig systems can seem complicated and daunting.

But according to one woodland conservation organisation, there’s a very simple way for producers to make their own contribution to the sustainability challenge: Plant more trees.

The Woodland Trust — a UK-based charity that works with farmers to integrate trees into farming systems — says planting trees not only helps improve the environmental footprint of pig farms but can also help drive productivity and boost businesses’ bottom lines.

“When managed correctly, trees can be hugely beneficial to livestock units,” says Helen Chesshire, the trust’s farming and land use senior advisor.

“Trees can help with saving inputs, increasing productivity and protecting natural resources, so it’s about finding ways to integrate them into individual farming systems to make them work for the farmer.”

Planting trees doesn’t mean taking land out of food production to create a forest, she says. Instead it’s about using trees in a way that solves problems farmers may have, brings benefits to their farming systems and helps improve businesses’ environmental sustainability.

“Trees won’t solve one particular problem, but they are part of a preventative program that will address a range of issues,” Ms Chesshire adds. “Collectively, they can make a farm and the landscape more efficient.”

Improving animal welfare

One of the significant benefits of planting trees on outdoor pig units is the contribution they can make to animal health and welfare.

All farm animals are vulnerable to increases in temperature and, for pigs in outdoor systems, solar radiation, which can affect feed intake, reproductive performance and susceptibility to disease.

Outdoor-housed pigs can suffer from heat stress and sunburn, which damages skin and can interfere with reproduction, including reluctance for sows to take the boar, re-absorption of embryos or abortion.

Planting shelter belts offers shade to pigs, which helps them maintain their temperatures and, in turn, helps increase productivity, Ms Chesshire says.

“Shelter is also an important factor in reducing the impact of cold weather,” she adds. “Animals exposed to cold winds use more of the available feed just to keep warm, and they also adopt irregular feeding patterns and become more vulnerable to disease.

“Providing tree-shelter belts can improve feed conversion and weight gain, as well as animal health.”

Managing soil and reducing erosion

In terms of boosting environmental sustainability, trees can play a significant role in managing soils and reducing erosion.

According to a Cornell University study, damage from soil erosion worldwide costs about $400 billion ($1=€1.13=£1.45, May 17, 2016) per year, while the cost to the US in productivity losses alone is more than $37 billion.

Professor David Pimentel, the study’s author, says soil erosion is second only to population growth as the biggest environmental problem the world faces.

But, the Woodland Trust says, this is where trees can help. Planting trees along contours or areas known to be particularly windy can create natural barriers that protect soil and crops from the full impact of strong winds or rain.

Deep-rooting trees also help improve soil stability, while increased organic matter from leaf litter can improve the soil’s structure and reduce surface water run-off.

Crop shelter

On mixed farms, trees can also provide shelter for crops, helping encourage germination, boosting growth rates and resulting in higher yields.

Studies show shelter belts can increase wheat yields by at least 3.5 per cent as a result of efficient water usage — and those results are even more pronounced during periods of drought.

“Planting field-edge or in-field shelter belts can help protect plants against drought by modifying microclimates around the crop,” Chesshire says. “They reduce wind speeds which can otherwise remove moisture from the air.”

Even modest increases in tree and hedge cover can increase water infiltration, which means surface water run-off is reduced, and the rate rainwater reaches streams and rivers is slowed, she adds.

This reduces peak flows in water courses and can potentially reduce the risk of flooding downstream.

Reducing pollution

One of the other environmental benefits is trees’ ability to tackle pollution. In the UK alone, the costs of treating water due to pollution from soil erosion is about £21 million every year, while about 25 per cent of phosphates and 50 per cent of nitrates found in rivers are from agricultural sources.

By limiting run-off and trapping pollutants bound to soil particles, trees can act as nutrient sinks, reducing water pollution.

What’s more, over 90 per cent of the ammonia emitted across Europe is from agriculture, mainly from the breakdown of excreted urea from livestock.

Tree belts as narrow as 10 meters (32 feet) have been shown to reduce ammonia emissions by more than 50 per cent, as they create a physical barrier which captures pollutants and ammonia from livestock units.

Boosting incomes

Finally, farmers looking for ways to diversify their businesses can also reap the benefits of planting trees, either from selling harvested wood or using it as an alternative energy source.

Studies have also shown the potential for pig farmers to improve their bottom lines by developing silvopastoral systems, which combine forestry and animal-grazing in a mutually beneficial way. By planting trees where pigs can roam, producers can achieve premiums on their animals by promoting them as “forest-reared.”

“Silvopastoral systems address all of the concerns [about sustainable production] with the added benefit of increased production in the long term,” says Professor Donald Bloom of the University of Cambridge, whose research has studied the benefits of trees in livestock systems.

“It’s clear they increase biodiversity, improve animal welfare and provide good working conditions while enabling a profitable farming business. The next step is to get farmers to adopt this proven, sustainable model.”

Taken from Voice of Sustainable Pork