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Soil biodiversity matters

Most people have never heard of soil biodiversity, the poor man’s rainforest. But we all should know about it and especially how it maintains critical processes…

In 1987 I went to the University of Zimbabwe on a Commonwealth universities fellowship where for two years I was a bushy-tailed postdoctoral scientist. It kick-started my career as an ecologist and I’ll be forever grateful. It was the opportunity of a lifetime. 

young academic starts at his new job in Zimbabwe
Source: Alloporus

You can almost smell the naivety of a 26-year-old Brit in mother Africa for the first time.

Zimbabwe at that time was a vibrant place still buzzing with the euphoria of newly minted country with most of its infrastructure and economy still functioning despite sanctions during the independence struggle. 

The friendly and accomodating locals all wore a wide grin.

Mentors are important

As a privilege of my scholarship, I became a member of the Tropical Soil Biology and Fertility (TSBF) program, a research group based in the Department of Biological Sciences.

At various seminars and field visits across Africa, I was introduced to and helped by many senior soil biologists from all around the world. That exposure so early in my academic career was extremely valuable. It made me realize what it took to achieve academic success. 

One individual in particular, Professor Diana Wall, became a mentor of sorts and invited me to several workshops and conferences she organised on above and below-ground biodiversity. Her pioneering work in soil ecology in the Antarctic is seminal even now as was her leadership of the Natural Resource Ecology Laboratory at Colorado State University from 1992 to 2006. NREL has helped many thousands of youngsters on the way to productive ecological contributions partly because they all learned of the importance of soil biology. 

After a long and distinguished career, Diana continues to promote soil biology as a critical missing link in our understanding of the way the world works, especially for food security.

In this, she’s correct because for some reason humanity has no desire to understand what’s going on beneath our feet. 

Soil biology is important

Soil is the most important component of our food as without it we wouldn’t have any. 

A small fraction of global food is produced in greenhouses with their roots in water or even air but 99% of the plants that grow on the planet have their roots in soil including food crops and the livestock that feed on the pastures or are fed fodder crops in feedlots. It’s all down to soil but only a handful of specialists and some canny farmers know very much about it. 

We don’t even know where to put it. 

For example, in New South Wales you can find soil in several government departments from water to planning to agriculture, environmental protection, and conservation. The already sparse expertise is split and separated around these various government institutions. 

Similarly, research on soil is partitioned into its various components so the agronomists do their soil work while the soil scientists are grappling with soil physics, soil chemistry and mapping of soil. 

The ecologists have a crack at soil too typically with a focus on the soil animals and microbiome. These specialists are few in number and must try to understand how organisms influence soil processes without knowing much about the myriad of soil organisms that make it happen. 

soil eroded away to show the profile of tree roots
Photo by Alloporus.

Soil profile showing layers and plant root architecture. Miombo woodland, Zimbabwe.

Soil biodiversity is important 

Lack of focus on soils, particularly on soil biodiversity, is perplexing. 

The animals and  microbes in soil, the soil biodiversity, supports the transfer of nutrients and water to plant roots, the storage of carbon, and is the foundation allowing plants to grow tall. It is the engine that keeps us alive.

When an engine is ignored sooner or later it breaks down and we’re seeing this happening repeatedly throughout the world with a range of different consequences, none of them pretty. 

It is estimated that by 1990 ~15% of the world’s soils were in some way degraded and each year many agricultural fields are abandoned as the soils are no longer able to support crops or livestock.

Current rates of erosion on agricultural land are estimated to be an order of magnitude higher than that of natural erosion or soil formation processes.

Concepts like soil health that reflect the ability of soils to support plant growth do breakthrough occasionally but any metrics that describe such concepts are going in the wrong direction. 

A handful of soil biologists around the place know this and have explained it in various forums. But their message is often forgotten or ignored. Even the farmers who understand the importance of soil and can tell you good soil from how it smells don’t pass this on to the general public.  

In policy and public perception, there’s no penetration at all, no understanding of the importance of soil in the public mind. 

Photo by Shahan Khan on Unsplash

Even agricultural soil is full of biology

Soil is more important than climate

Arguably soil health is far more important than climate change to our long-term survival because without healthy soil there is not enough food for us to survive long enough to fix the climate. All a bit melodramatic perhaps, yet there is truth. Food insecurity is a destabilising risk that is with us right now.

We wouldn’t live very long if all soils became unhealthy. Yet we could probably survive most of the climate change impacts even if they were disruptive. But only if the soils are in good shape. 

Recently I read a paper by Diana Wall and a couple of her colleagues. She’s now towards the end of her career and is still active in promoting soil biodiversity as a critical component of our understanding. 

Geisen, S., Wall, D. H., & van der Putten, W. H. (2019). Challenges and opportunities for soil biodiversity in the anthropocene. Current Biology, 29(19), R1036-R1044.

When I read the paper, and I encourage you to do so, I found one of the reasons why soil biodiversity is considered such an esoteric subject with very little understanding by the general public. 

And it’s not to do with the fact that soils are hidden away or that the majority of soil organisms are tiny microscopic critters, hard to understand what they do and they only do that their job because of their vast numbers. 

The words used suggest that soil biodiversity is an object. Like a koala or an elephant is an object. 

Soil biodiversity is something they said, it’s a thing. It’s a component of something, perhaps a piston and an engine. You can see it, you can decide whether it’s in good shape, and see if it needs oil or grease. It’s a specific thing. 

By extension, if specific things are lost the engine doesn’t work. If specific things become corroded or bent out of shape again, either the engine is compromised or it doesn’t work at all. 

This idea of objectifying is how the conservation movement operates. They identify objects to save and protect. 

I have to say that I was a little bit surprised. My recollections of Diana Wall’s contributions and her intellect were that she’s way smarter than that. She knows much more about how the systems work, but the communication was designed to get traction. The Intent was to make information accessible to a wider audience. 

But in objectification, everything about why soil biodiversity matters is lost. 

Ecology is not about objects. It is all about processes

Soil processes are important

Objects are present and they contribute to delivering process, but it’s the processes that matter—decomposition, nutrient cycling, water balance. And it’s understanding that process in its resistance and resilience that is critical to how humanity is going to persist, even if it is at all. 

At sustainably FED we think objectifying is a mistake and a real problem particularly when the soil biodiversity objects are so poorly known and have more yuck factor than charisma. 

Scientists are still unsure of the types, numbers or distribution patterns of soil organisms. Very little is known even about how to define the types given that for many soil microbes species concepts fall over. 

What we do know is that soil biodiversity is incredibly diverse. And like rainforests, vulnerable to disturbances outside the norm. Land clearing for example, or grazing rangeland with livestock, rather than bison. 

cow grazes on sparse grass in a desert environment
Photo by Jeremy Bezanger on Unsplash

Soil carbon and the biodiversity that goes with it are easily lost

What sustainably FED suggests…

Objectifying may make sense to get a message across. But in focusing on the objects we fall into the preservation of objects trap and that’s not what is needed. Global food security requires the maintenance of soil processes. 

And it doesn’t matter which objects were involved as long as we can be sure that the processes themselves remain. 

Our message is this—understand the processes. 

Find out why soil processes are resilient and resistant for as long as it takes. 

And what we’re talking about is a requirement to produce food at 22 trillion calories a day for at least a hundred years. Our human problem is acute and the only solution to that problem is to maintain soil processes long enough for humanity to solve its many other pressing problems. 

More reading

Oldeman, L. R. (1992). Global extent of soil degradation. In Bi-Annual Report 1991-1992/ISRIC (pp. 19-36). ISRIC.

Ramankutty, N., Evan, A. T., Monfreda, C., & Foley, J. A. (2008). Farming the planet: 1. Geographic distribution of global agricultural lands in the year 2000. Global biogeochemical cycles, 22(1).

Ramankutty, N., Mehrabi, Z., Waha, K., Jarvis, L., Kremen, C., Herrero, M., & Rieseberg, L. H. (2018). Trends in global agricultural land use: implications for environmental health and food security. Annual review of plant biology, 69, 789-815.

Thornton, P. K., & Herrero, M. (2015). Adapting to climate change in the mixed crop and livestock farming systems in sub-Saharan Africa. Nature Climate Change, 5(9), 830-836.

Hero image from a photo by Tatenda Mapigoti on Unsplash


Mark is an ecology nerd who was cursed with an entrepreneurial gene and a big picture view making him a rare beast, uncomfortable in the ivory towers and the disconnected silos of the public service. Despite this he has made it through a 40+ year career as a scientist and for some unknown reason still likes to read scientific papers.

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