Today, December 5th, is World Soil Day. It comes hot on the heels of recent events like the Global Landscapes Forum and 22nd Conference of the Parties (COP 22) in Morocco, which have galvanized the world to act with urgency on the Paris Agreement on climate change.

Sinking more carbon in the ground is more appealing than ever to meet new emissions targets. But it’s not that easy.

Maintaining carbon that is already stored in the soil is a challenge in itself. Evidence just published in Nature shows that rising temperatures are stimulating our soils to lose carbon and emit it to the atmosphere – the problem is particularly serious in areas with the highest carbon stores.

What’s happening in soils is accelerating the accumulation of greenhouse gases in the atmosphere and increasing the rate of global warming. So it’s clear we have a problem.

However, if they are well managed, our soils can also be part of the solution. The amount of carbon stored in the soil is huge – two to three times higher than what is currently in the atmosphere.

CIAT’s research suggests that, globally, soils could be managed to help remove carbon dioxide from the atmosphere and increase storage, which in turn, could help reverse the trend reported in the Nature paper.

Mercy Wambui, a farmer in Kenya's Tana River Watershed, measures rainfall on her farm to track soil run-off. Credit; Georgina Smith / CIAT

Mercy Wambui, a farmer in Kenya’s Tana River Watershed, works with researchers to track soil run-off on her farm. G.Smith/CIAT

Neglected highlands: call to invest in tropical soils

In this century, soils could absorb between 30 and 60 billion tonnes of carbon, which is between 3 and 9 percent of likely global emissions, and most of that could come in the next 35 years if appropriate incentives are created.

In tropical agricultural landscapes, the fact is we don’t have enough available data on soil carbon and we need it. Even the recent Nature study acknowledges that the analysis doesn’t include tropical ecosystems in Africa: the data is not available.

“It’s clear the world is not doing enough in the tropics to facilitate the type of change that we need to see in soils research,” said CIAT’s Director of Soils Research, Dr. Louis Verchot. “At a time when problems are increasing and the world has settled on new Sustainable Development Goals and the Paris Agreement, governments across the globe are disinvesting in rural areas.“

Highlands are particularly vulnerable: global food insecurity in these areas grew by 30 percent between 2000 and 2012, contrary to trends everywhere else. Almost half of those living in rural mountain areas in in developing countries are vulnerable to hunger, poverty and malnutrition – yet these are often the most diverse ecosystems, with higher rainfall and better quality land.

A good start would be to invest in measuring how much carbon is stored in soils already, and how much more soils could potentially sequester through improved management practices.

For example, a new program supported by the German Deutsche Gesellschaft für Internationale Zusammenarbeit (GIZ), Soil Protection and Rehabilitation for Food Security, is enabling CIAT scientists to identify agricultural management practices that boost food security while preserving soils and possibly increasing its carbon content.

Planting grass strips on sloping land can trap soil, preventing erosion.

Rachael Njeri planting grass strips on sloping land to prevent rainwater run-off. G.Smith/CIAT

Land restoration agenda: action now

Loss of soil organic carbon leads to land degradation – ultimately triggering low agricultural productivity. Restoring soil health is an important component of the global land restoration agenda – but preventing soils from degrading and releasing further carbon trapped in the ground is equally important. Some key lessons we’ve already learned include:

  • Understanding soil diversity is vital to guide decisions about how to restore them. But we also need to better understand the diversity of farming systems in general. Different farming systems require different interventions – like terraces on slopes to prevent soil erosion for example. Developing context-specific interventions that meet farmers’ preferences is key to getting the agenda moving on the ground.
  • When it comes to capturing more carbon in the soil, we need a more inclusive strategy and more realistic options for tracking carbon capture. We need to consider how people farm the land; how communities use their resources and can benefit from protecting them.
  • Off-farm factors are important in farmer decision making, and we need to better understand what these are. Access to markets to sell their produce; availability of food during dry seasons – farmers have many things to consider above and beyond protecting their soils.
  • Youth will need to be better involved in soil rehabilitation initiatives. That’s because they’re the farmers of the future: many of those involved in soils initiatives today will not be here to see the long-term impact of these investments.

World Soil Day: soils and pulses, a symbiosis for life

That’s the theme of World Soil Day this year. It points to some solutions already enabling farmers to fetch a higher income, put more food on the table and adapt to a changing climate. Like inter-cropping with more nutritious beans bred to contain more iron while also combating drought and disease, or climbing beans that produce double or even triple yields.

Yet to have impact across landscapes and continents, farmers – and other decision makers – need better information about where to target limited investments. Trade-offs will be unavoidable: smallholder farmers always have to prioritize food security, despite having less land and natural resources with which to produce food.

So which soil management practices can improve carbon capture, maintain soil carbon and boost yields of crops like improved beans? How much carbon can we realistically capture in our soils? For now, those questions remain unanswered.

Call to Action:

  • Site-specific tools can be developed to present decision makers with the bigger picture of where soils are most degraded, and which areas should be prioritized for investment to improve soil carbon stocks.
  • Ready-to-finance packages of best-bet land and soil conservation practices can highlight which practices are most appropriate to enhance soil organic carbon stocks in particular regions.
  • Increasing carbon in the landscape will require landscape mapping and site-specific data to guide decision makers about where to invest in specific management practices.
  • Further research is needed to identify drivers of land use change at regional, national and sub-national scales, to develop policies to enhance carbon capture on agricultural land, benefiting farmers and communities.

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