May 27th, 2017
We rely on soil to provide healthy food, clean water, support wildlife, store carbon, prevent flooding and ultimately maintain livelihoods around the country.
Yet over the last half a century, Ireland’s soils have come under increasing pressure from land use changes, intensification of agriculture, erosion and overgrazing, disposal of organic wastes to soils, afforestation, industry and urbanisation.
Our newest contributor, Shane O’Reilly, a research scientist based in UCD and MIT, explores these issues below, and how we can help protect and regenerate our soil in the future.
Soil is a dynamic living substance vital for life on Earth. It is also one of our most diverse ecosystems, with numerous studies showing how thousands of different microbial species can live in one single gram of soil.
Soil is also the most fundamental requirement for agriculture and has been feeding global populations since the dawn of agricultural practices about 10,000 years ago. Soil takes thousands of years to form, yet it can be degraded in an instant due to gross mismanagement by humankind.
There is ample historical evidence that civilisations mismanaging their soils collapsed as a result. It is also clear that we are also currently facing a global soil crisis and urgent action is needed if we wish to avoid disaster in the near future.
This global soil crisis has resulted from radical land use change and poor agricultural practices and the consequences are widespread – soil erosion, desertification, accumulation of salinity, nutrient loss and pollution.
Soil degradation has now affected about one-third of global land area. The UN’s Food and Agriculture Organisation (FAO) estimates that about one per cent of the global land area is degraded each year.
In total, it is estimated that 33 per cent of arable land has been lost to soil erosion or pollution. At this rate, and with current practices and population growth, the world’s topsoil could be gone withing decades.
Why is soil organic carbon important?
Organic molecules are the building blocks of life. Generally, the most important factor that determines healthy or good quality soil is organic matter.
The word ‘organic’ here describes the molecules of carbon that bond together, often containing hydrogen, oxygen and nitrogen. In soil, the majority of organic matter is composed of an insoluble residue from plants and microorganism exudates – a fluid discharged from cells – and their decaying remains. Or as it is more commonly known – humus.
Despite normally making up less than 5 per cent of soil by weight, soil organic carbon supplies essential nutrients for agricultural and biological productivity and helps maintain soil structure and water content.
Loss of soil organic carbon has been caused by desertification, deforestation, soil erosion and intensive crop production. Globally it is estimated that between 50 and 70 per cent of the world’s cultivated soils have now lost their original carbon stock.
The consequences of this include substantial decreases in soil quality and biodiversity and changes to the physical properties of soil. While excessive amounts of soil organic carbon are being eroded, leached or respired to the atmosphere, they are not being replaced by sufficient amounts of new organic carbon.
Soil is also one of the largest pools of carbon on Earth and a major component of the global carbon cycle. There is three times more carbon in the soil than in the atmosphere, and over four times more than in all land plants combined.
Substantial land use change across the globe, together with historical and modern day agricultural practices, has caused widespread loss of soil carbon to the atmosphere as carbon dioxide. This is second only to fossil fuels as a source of carbon dioxide fueling anthropogenic climate change.
Therefore, strategies to minimise soil degradation and restore soil health will have a double impact, both reducing carbon dioxide loss and increasing carbon dioxide uptake and sequestration in plants and soil. But are we doing enough to lessen our impact on our soil?
Land and soil mismanagement in Ireland
While lauded for our lush green landscape, we have witnessed and been responsible for large scale impacts on our soil dating back hundreds of years. For example, both deforestation in the 18th century and famine and depopulation in the 19th century brought about wholesale changes on our island.
More recently, increases in pastoral grassland and the spread of urban areas have had major impacts on our soil. Arguably the most critical issue in Ireland relates to the loss of peatlands.
Globally, peatlands only cover only around two or three per cent of land surface but store up to 30 per cent of total soil carbon making peatlands vitally important carbon sinks. They also support unique biodiversity.
Peatlands are an important wetland ecosystem, accounting for 15 per cent of Ireland’s land area. We, in fact, hold eight per cent of the world’s blanket bogs on our small island.
Unfortunately, only about 21 per cent of our peatlands is in relatively intact conditions, with turf-cutting, industrial peat extraction, commercial afforestation and urban development taking its toll on our bogs.
In addition to stresses faced by peatlands in northern temperate locations such as Ireland, tropical peatlands are also being destroyed by the likes of the spread of palm oil plantations.
Stop Treating Soil like Dirt
It is clear that maintaining our soils is fundamentally tied to protecting our economy, food, health, biodiversity and climate. So what can we do to protect and restore our soil?
There are a number of sustainable management strategies that can be used to restore the organic content of soil, including manuring, no-tillage, conservation tillage, rotating crops, cover cropping and agroforestry.
Numerous studies have shown that sustainable agriculture can match or exceed productivity and profit and increase soil organic carbon, while also reducing environmental impacts. Unfortunately, only a fraction of global agriculture uses sustainable techniques at present.
Currently, we have EU legislation to protect water and air, but, despite its importance and the recognised global crisis we have on our hands, we do not have an EU Directive dedicated to protecting our soils. Without legislation, we have little chance of addressing soil degradation.
People4Soil is a campaign run by the Environmental Pillar that aims to change this by using a European Citizen’s Initiative petition to call on the European Commission to pass a dedicated Soil Directive.
Read about the People4Soil campaign and sign the petition here.