Soils Are Threatened: Can We Halt The Problem?

By Roberta Attanasio

Today, December 4, 2015, is World Soil Day — a day to connect people with soils, and raise awareness of their critical importance in our lives.

Soils — the reservoir for at least a quarter of global biodiversity — have been neglected for too long. We fail to connect soil with our food, water, climate, and life. The maintenance or enhancement of global soil resources is essential to meet the world’s need for food, water, and energy security.

Soil loss is an unfolding global disaster that will have catastrophic effects on world food production, according to scientists from the University of Sheffield’s Grantham Centre for Sustainable Futures.  “At the moment, intensive agriculture is unsustainable — under the intensive farming system current crop yields are maintained through the heavy use of fertilizers, which require high energy inputs to supply inorganic nitrogen via the industrial Haber-Bosch process. This consumes five per cent of the world’s natural gas production and two per cent of the world’s annual energy supply.” The scientists’ research is published in a report (A sustainable model for intensive agriculture) presented at the recent climate talks in Paris.

But soil is important not only for agricultural practices. “Soil is a vital part of the natural environment. It is just as important as plants, animals, rocks, landforms, lakes, and rivers. It influences the distribution of plant species, and provides a habitat for a wide range of organisms. It controls the flow of water and chemical substances between the atmosphere and the earth, and acts as both a source and store for gasses in the atmosphere.

Soil, together with the plant and animal life it supports, the rock on which it develops, its position in the landscape and the climate it experiences, form an amazingly intricate natural system. Soil may look still and lifeless, but this impression couldn’t be further from the truth. It is constantly changing and developing through time. Soil is always responding to changes in environmental factors, along with the influences of man and land use. Some changes in the soil will be of short duration and reversible, others will be a permanent feature of soil development.”

So, what is the current status of soils, considering the influences of man and land use? We know that soil loss is an unfolding global disaster. There is another report that adds more information: The Status of the World’s Soil Resources, which has been produced by FAO’s Intergovernmental Technical Panel on Soils, and it has been released today, on Soil World Day.

The report, which brings together the work of 200 soil scientists from 60 countries, concludes that the majority of the world’s soil resources are in only fair, poor or very poor condition, and that conditions are getting worse in far more cases than they are improving. In particular, 33 percent of land is moderately to highly degraded due to erosion, salinization, compaction, acidification, and chemical pollution of soils.

However, as stated by FAO Director-General José Graziano da Silva in the foreword to the 650 page-long report, “The report also offers evidence that this loss of soil resources and functions can be avoided. Sustainable soil management, using scientific and local knowledge and evidence-based, proven approaches and technologies, can increase nutritious food supply, provide a valuable lever for climate regulation and safeguarding ecosystem services.”

He also wrote: “We can expect that the extensive analytical contents of this report will greatly assist in galvanizing action at all levels towards sustainable soil management, also in line with the recommendations contained in the updated World Soil Charter and as a firm contribution to achieve the Sustainable Development Goals.” The report notes that, to feed a global population of some 7.3 billion, over 35 percent of the Earth’s ice-free land area has been converted to agriculture.

The result is that soils have been cleared of natural vegetation to grow crops or graze livestock and, consequently, suffer from sharp increases in erosion and steep losses in soil carbon, nutrients and soil biodiversity. Urbanization is also taking a major toll. The rapid growth of cities has degraded increasingly wide areas, and contaminated soils with excess salt, acidity and heavy metals, compacting them under heavy machinery, and sealing them permanently under asphalt and concrete.

Climate change is an additional strong driver of soil change, the report finds. Higher temperatures and related extreme weather events such as droughts, floods and storms impact soil quantity and fertility in a number of ways, including reducing moisture and depleting the layers of nutrient-rich topsoil. They also contribute to an increase in the rate of soil erosion and shoreline retreat.

However, it is possible to reverse the trend of continuous soil degradation and, through sustainable soil management, achieve healthy soils. The report focuses on the 10 main threats to soil functions: soil erosion, soil organic carbon loss, nutrient imbalance, soil acidification, soil contamination, waterlogging, soil compaction, soil sealing, salinization and loss of soil biodiversity. It notes how there is a general consensus on soil-related strategies that can, on the one hand, increase the supply of food, while on the other, minimize harmful environmental impacts.

The solution proposed is one that focuses on sustainable soil management — and requires the participation of a broad level of stakeholders, ranging from governments to small-holder farmers. Erosion, for example, can be curbed by reducing or eliminating tillage — the digging, stirring, and overturning of soil — and using crop residues to protect the soil surface from the effects of rain and winds. Similarly, soils suffering from nutrient deficits can be restored, and yields increased, by returning crop residues and other organic material to the soil, employing crop rotation with nitrogen-fixing crops, and making judicious use of organic and mineral fertilizers.

The FAO report seems to reach conclusions similar to those from The Grantham Centre for Sustainable Futures. Indeed, Duncan Cameron, professor of plant and soil biology at the University of Sheffield, told The Guardian: “We need a radical solution, which is to re-engineer our agricultural system. We need to take land out of production for a long time to allow soil carbon to rebuild and become stable. We already have lots of land — it’s being used for pasture by the meat and dairy industries. Rather than keep it separated, we need to bring it into rotation, so that that there is more land in the system and less is being used at any one time.”

He added that such a solution would involve direct government intervention, funding for farmers and “brave” policymaking. “We can’t blame the farmers in this. We need to provide the capitalisation to help them rather than say, ‘Here’s a new policy, go and do it,” he said, “We have the technology. We just need the political will to give us a fighting chance of solving this problem.”