World Soil Day – what can we do to protect our soil?
In discussions around sustainability, we often talk about air quality and water quality, and for good reason. However, there’s another vital resource that maybe doesn’t get the attention it deserves: soil.
Maybe this is because we are less likely to sense declining soil health until its long-term effect on trees and crops becomes apparent. Unlike air and water pollution, which we can often see or smell differences from day to day, or location to location, it’s all too easy to overlook what’s happening beneath our feet.
“There is a vast reservoir of biodiversity living in the soil that is out of sight and is generally out of mind. But few things matter more to humans because we rely on the soil to produce food.” Explains Professor Richard Bardgett, from the University of Manchester.
Healthy soil is teaming with billions of microbes, fungi, insects, worms, and other forms of microscopic life that are the foundations of the entire human and animal food chains.
Did you know, a quarter of all animal species live under the soil surface – it’s a busy place. When this eco-system is damaged, it can take many years to recover.
The Importance Of Soil Health
Soil quality underpins so much in our environment, communities, economies, and our health. Plants are vital for mitigating emissions and air pollution, yet without the right soil conditions they cannot survive. In addition to air-sourced oxygen, hydrogen, and carbon dioxide, plants need 15 other essential elements from the soil. While some plants can obtain nitrogen from air, most draw it from the soil. By volume, plant cells are made up of mostly carbon and nitrogen.
It’s estimated that over 95% of global food supplies are directly dependent on soil health, yet according to the Sustainable Food Trust, more than half of all soils globally are classified as degraded.
Soil is a great carbon sink, keeping vast amounts from entering the atmosphere as CO2. A whooping 1,500 billion tonnes of carbon – three times that in the world’s forests and vegetation – are stored in soil.
What Is Soil?
Soil forms naturally from rock weathering, with its fertility and structure improved over thousands of years of repeated cycles of plant growth and decay, and animals processing plant matter through their digestive systems.
Soil contains inorganic grains of ‘parent rocks’ which typically includes various ratios of larger sand grits, and microscopic clay particles, mixed with organic matter from decayed animal and plant matter. Between these, the essential micro-nutrients are available to new growth.
Threats To Soil – And Actions To Remedy Them
From catastrophic environmental disasters to a slow and steady depletion of nutrients, soil faces mechanical, chemistry, and biological threats.
Industrial, Linear Farming Models
The Problem:
Intense farming, in which harvested food is taken off-site for consumption elsewhere has depleted the soil’s stock of nutrients. Artificial fertillisers can be applied to sustain the farming value for longer, but this leaves an incomplete nutrient chain, leading to a long-term loss of soil microbial activity, symbiotic fungi, and water absorption capacity of the soil’s structure.
Today, food prices are driven by fertiliser prices, leaving low and middle income economies vulnerable to global fertiliser supply-chain shocks.
A Solution:
One of the most promising answers to this linear food chain is the growth in anaerobic digestion plants. These facilities collect food waste and break it down in closed digesters, resulting in digestate ‘cake’ which is spread back onto the fields, completing the essential elements circularity.
This circular economy model, along with the renewable energy extracted from the processing, lies behind the UK’s move to divert food waste from landfill and incineration to AD plants. Food waste regulation changes, first announced in Oct 2023 make it mandatory for business and institutions in England to separate food leftovers from dry recyclables from March 2025. This will make it feasible to return a larger amount of beneficial organic material back to farmland via advanced AD plants.
Smaller, farm-based AD plants and better treatment of animal manure slurries are decreasing the nutrient loss of soil and also the overall emissions from livestock farming.
Along with nutrient recycling, natural fertilizer such as potash and polyhalite has been found near the North Yorkshire coast, although the start of extraction has been frustrated by changes in the owner’s ‘business model’.
Flooding
The Problem:
Climate change is increasing the severity of floods in many places, causing a loss of topsoil through erosion and contamination. Runoff water can carry pollutants onto fields, and seawater surges makes land barren through salination.
Even good old soil, when it enters watercourses causes environmental damage by diverting and blocking the natural flow of rivers, cutting out sunlight, starving aquatic life of oxygen as it breaks down, or causing algae blooms from high nutrient loading.
Some Solutions:
Many changes to the way we operate can mitigate the effects of flooding. Sustainable Urban Drainage replaces the traditional hard surfacing with soakaways and permeable surfacing to decrease flash-flooding. Prevention of site runoff water, particularly from construction sites and industrial yards is essential to stopping soil pollution. EnviroHub produce systems for correcting high pH concrete washout water and removing suspended silt from dirty water. Together with pumping, these allow clean water disposal offsite in a controlled, sensitive manner using automated or manual controls.
Good soil structure, along with plant roots, absorb rainfall and act as a huge sponge-like reservoir, returning clean water over time to sustain all forms of life.
When extreme rainfall is forecast, flooding can be reduced by lowering the levels of stormwater tanks and lagoons ahead of the storm.
Regular desilting of retention and attenuation ponds maintain storm readiness, as does drain and filter-trap clearing.
Drought
The Problem:
The other side of climate change is the increase in hotter, drier seasons for many regions. This increases soil loss through wind “sand storms”. Lack of irrigation increases plant loss, exposing more soil to weather erosion.
Possible Solution:
Conserving water is vital in regions prone to drought. Industries that use water in their production processes can recycle this ‘process water’ in a closed loop system. This usually involves restoring the water to its original properties, whether that be cooling it back to ambient temperature (via a heat exchanger), correcting it’s pH (with EnviroHub dosing and treatment tanks), or removing contaminants using filtration, lamella settlement, vibration separation, or centrifuges. A closed-loop system makes the process resilient and self-sufficient without impacting the local environment or public water supplies.
Leaching Of Chemicals And Effluent
Leaching is a process whereby soluble solids in a mixture dissolve out of their original source material into a leachate. Sometimes this process is harnessed to extract valued minerals or remove undesired elements. Examples of beneficial leaching include steeping a teabag in water, or washing salt out of soil by flushing it with fresh water.
The Problem:
If industrial chemicals, or even naturally occurring substances in high concentrations spill into soil, it is very difficult to clean it out. For instance, iron (Fe) and lime (CaO) dissolve in water and can alter the pH values of soil. So-called “heavy metals” are another example of naturally occurring elements which damage cell functionality. Runoff from yards and roads often carries hydrocarbons, which if they enter soil permeate through it.
Landfill leachate can contain a cocktail of chemicals and pollutants, while untreated sewage causes problems in soil, as it often contains pathogens, PFAS, and microplastics in its raw state.
Over-irrigation and flooding tends to leach vital micronutrients out of soil, even if it doesn’t erode the actual soil structure away.
Possible Solutions:
Preventing site runoff is crucial to protecting the environment, especially during periods of heavy rainfall. This is done through bunding, drainage, installing sumps in low laying zones, and pump and treat systems.
Storage ponds, lagoons and landfill sites should be lined with impermeable material to prevent contaminants leaching into surrounding soils.
Industrial effluents must be collected by licensed waste carriers, treated onsite, or discharged under consent from the local wastewater company (via combined sewer drain) or, under licence from the environmental authority, into a water course at a designated discharge point.
In summary, if we are to sustain our climate, food supplies, economy, and communities, we need to take deliberate and informed action to prevent soil degradation.
There are many innovative systems and proven techniques to help companies in their prevention of soil degradation. The optimum approach is very dependent on materials involved and the processing context.
The Atlantic Pumps group has a dry material handling division and a specialist slurry pumping and water treatment division, ensuring coverage across the spectrum.
Soil – its’ not just mud!
