We're aspiring to do better for our local surroundings, for our people and for our planet through teaching and research. We spoke to Professor Gary Bending from our Department of Life Sciences who is engaged in teaching and researching the sustainability of soil at Warwick.

November 2015

What sustainability research and teaching are you involved in at Warwick?

Sustainability is a central part of two modules that I teach, especially my Masters module on soil. Soil is one of those resources that people tend to take for granted, but it’s being degraded at quite an astonishing rate. There is worry for the long term viability and productivity of the world’s agricultural soils because they’re subject to salinisation, erosion from wind or water and desertification. In England and Wales, our soil erosion costs us £1bn per year.

Why are we losing our soils?

There are a number of reasons. If we urbanise agriculturally productive green-belt land, we lose the soil there. When we till soil, we increase its microbial activity, emitting carbon dioxide into the atmosphere. As soil carbon declines it becomes more susceptible to erosion.

But the loss of soil quality also causes other problems. It results in loss of fertility and agricultural crop and productivity loss. If we lose soil depth because of erosion, crops are less able to deal with drought, because their roots can't go as deep. Loss of soil also means the land is less able to hold onto water, so it moves rapidly to rivers following rainfall, leading to increased flood risk.

What else affects the soil?

Without the nitrogen fertiliser we add to soil, we could only feed half the world’s population. It takes a massive 1-2% of the world’s energy to fix the nitrogen from the atmosphere into ammonia but we benefit from increased productivity. The down side is that this nitrate can contaminate water, and together with loss of phosphate fertiliser, result in eutrophication (green ponds) and in many locations, marine dead-zones. It can get into susceptible terrestrial environments through atmospheric pollution and species in sensitive habitats can be lost as a result.

Pesticides used in agriculture can also be lost from soil into water, causing contamination. There’s a trade-off – although Europe’s use of pesticides costs €270 million – we actually gain €906 billion because we remove pests and increase the quality of our produce. You couldn’t feed the European population without them.

What does all this mean for your research?

I work to improve the sustainability of agriculture, and this research, in turn, helps to answer the bigger questions of food security. There are many global challenges to meet and we have to start by getting to grips with some soil issues! So I research the root zones of plants, trying to understand the diversity of the complex microbial systems in the soil and how they interact with the plants. Some of those microbes are pathogens and pests and we’re looking at the diseases they cause in plants.

Are you collaborating with any other departments or organisations?

We collaborate with the departments of Engineering and Chemistry at Warwick. With Chemistry, we’re looking at the way in which plants control microbes which live in and around their roots. Plants fix carbon in their leaves and anything up to a quarter of that carbon is transported to the roots. 10% of that is exuded from the roots as sugars and organic acids. Dr Mark Barrow is working with us to find out what controls this complicated chemical process.

Our colleagues in Engineering are experts in exchange of pollutants between water and sediment in river systems, and we’re working together to understand how chemicals behave in the environment. We’re particularly interested in how microbes inhabiting rivers are able to degrade pollutants. Funding from industrial partners has enabled us to work with Engineering to build some mini flumes so that we can quantify the behaviour of chemicals when we vary different aspects of the environment, such as water flow.

What’s the future of your research?

Hopefully we’ll get to a point when we can engineer the root environment. We’re interested in coming up with crop genotypes that harness the power of the nitrogen and phosphorus cycles so we can harvest more sustainable crops. We also hope to be able to reduce plants’ susceptibility to disease by either controlling the chemistry of the root and root zone – their metabolomes – or the way they influence the microbes which live in and around roots.

If you could change one thing that would improve the sustainability agenda, what would it be?

If I could change something I’d get people to appreciate their soil more. People take it for granted, and most people don’t even make the connection between food and the soil. People are amazed to hear that soil is living and how important it is for the world’s population. Our agricultural processes are gradually leading to losses of carbon from the soil and the maintenance of soil quality should be put firmly at the top of our agenda!

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Image: 20130920-OC-LSC-0422 by US Department of Agriculture (via Flickr)