By Alice Ruhweza, vice president of Programs and Partnerships at Conservation International (CI) in Africa and a 2019 Aspen New Voices Fellow, and Everline Ndenga, a senior technical manager at CI.
Soils hold 70 percent of the planet’s land-based carbon — three times the amount of carbon dioxide (CO2) in the atmosphere. Not only is carbon-rich soil a crucial tool in mitigating climate change, it is also essential to meet the food needs of Africa’s population, which is set to grow by 1.3 billion by 2050.
When soils are managed sustainably, they store organic carbon that locks in soil moisture and increases soil fertility; they also remove greenhouse gases from the atmosphere. Conversely, if they are poorly managed, soils release carbon into the atmosphere in the form of CO2, which can contribute to climate change.
Today, on a global basis, soil carbon is being released from the soil more quickly than it is being replaced. This dangerous trend must be reversed. To do so, we need to know exactly how much organic carbon is sequestered in the soil, not only country by country, but often meter by meter.
Most losses of soil carbon have been due to deforestation, along with harmful agricultural practices and soil erosion. Such losses have been pronounced in Africa. One research review estimates that soil organic carbon in croplands in southern Africa has plummeted by 25 to 53 percent. Other studies in Western Kenya found decreases of up to 85 percent following deforestation!
On the flip side, Africa has large areas with potential for greatly increasing soil organic carbon storage. Grasslands, for example, which form 30 percent of the continent’s surface area can store up to 50 percent of soil carbon. A recent assessment of soil carbon storage in sub-Saharan Africa by the French-initiated “4 per 1000” initiative found that practices such as agroforestry and conservation agriculture can restore soil carbon by more than 0.4 percent a year.
To realize this potential of restoring soil carbon on a large scale, governments, investors and farmers must first have accurate measures of soil carbon. It must be measured and be tracked as sequestration projects are implemented. To proceed with confidence, we must fill this data gap. Progress is being made.
During the recent Global Soil Week in Nairobi (May 26 – 30, 2019), discussions focused on creating an enabling environment for sustainable and climate resilient agriculture and soils were cited as the cornerstone for improved productivity and resilience. Yet despite the global commitments to conserve and improve the soils, action at the local level was missing. Land governance, including recognizing the rights of women and marginalized groups to access land for agriculture, proper local governance for land access and use, availability of information, extension and advisory services; and availability of finance and markets were identified as the main challenges hampering local actions towards sustainable soil management.
As part of information and advisory component, digital solutions were recognized as important to accelerate decision making in land restoration and agriculture development. As it is often said, you cannot manage what you cannot measure. Technology has now made it possible to assess, analyze and visualize the status of our soil resources.
In 2017, the U.N. Food and Agriculture Organization (FAO) released a comprehensive global map showing the amount of carbon stocks in the world’s soils. The map illustrated that globally, the top 30 centimeters of soil contains around 680 billion tons of carbon. Ten countries including Democratic Republic of Congo in Africa had more than 60 percent of the total soil organic carbon stocks. The map revealed to decision-makers where carbon-rich soils need to be preserved and in which regions action should be taken to foster further carbon sequestration.
On its part, Conservation International’s Vital Signs Program is addressing soil data gaps in many African countries. The program collects and integrates data on Agriculture, Ecosystems and Human Well-Being across several African nations. Between 2016 and 2018, Vital signs collected 5,969 soil samples from Tanzania, Uganda, Rwanda and Ghana. It then partnered with the International Soil Reference and Information Center (ISRIC) to generate high resolution maps of soil nutrient content for Ghana, Kenya, Rwanda, Uganda and Tanzania.
Most of these countries did not have up-to-date soil maps. For example, Uganda’s last soil map was from 1960. The new maps not only show the soil nutrient content of each area, but they also show which areas are suitable for which crops. Now, the countries are using these maps to inform decisions on zoning for agriculture and identify priority areas for forest landscape restoration. They are also including the soil data in reporting on their National Climate Change commitments under the U.N Framework Convention on Climate Change.
Similarly, Conservation International’s Trends.Earth program has developed baselines maps for landcover and soil organic carbon for Ghana, Nigeria, Malawi, Burkina Faso, Niger, Eswatini, Burundi, Ethiopia, Uganda, Kenya, Tanzania and Senegal. Over 142 researchers and decision makers were trained to use Trends-Earth to monitor and assess trends in land productivity, land cover and soil organic carbon. Countries are now using the maps to report on progress toward their commitments under the U.N. Convention to Combat Desertification (UNCCD) and the Sustainable Development Goals.
One could argue that given the widespread degradation of the earth’s soils, not all can be restored, and it will take many decades to rebuild the soil health of vast regions. But the alternative of allowing the continued destruction of top soil would not only squander a crucial opportunity to mitigate climate change, but also deepen the global crisis of hunger.