As Heads of States were signing the Paris Climate Agreement last December, the 4p1000 global initiative was launched with the aim to increase the amount of organic carbon in soils by four parts per thousand every year. Such sequestration could quell the rise of global CO2 in the atmosphere.

Enriching soils with organic carbon is not only about mitigating climate change; it is a precondition to preserving soil health. And it matters a lot. Healthy soils are the foundation of our food security, providing important ecosystem services, like retaining water and nutrients for crops, protecting against soil erosion, and playing host to more soil microorganisms and worms. With healthier soils, farmers get higher crop yields; increasing the soil organic carbon sink in degraded soils by 1 ton per hectare increases crop yields of maize by 100 to 300 kg/ha.

Deborah Bossio took part in a panel discussion on soils at a COP21 side event.

CIAT.

Soil health and economic development are strongly interconnected. Malawi, one of the poorest countries in Africa, loses an estimated 11% of its GDP because of land degradation. Soil health is a prerequisite for the long-term sustainable impact of agricultural development programs in the global South.

“The trouble is that we don’t know much about soil health because quantifying it usually involves expensive and cumbersome methods”, says soil scientist Keith Shepherd who leads WLE’s Decision Analysis and Information Systems cross-cutting theme, “but this is changing as soil research is undertaking a big data revolution to map soils faster and at lower cost.”

Let there be light! Building low-cost, user-friendly soil information systems

Instead of measuring a long series of chemical reactions in laboratory test tubes, imagine being able to characterize soils by simply measuring the quantity of light reflected from a sample. Infra-red spectroscopy is fast – a sample can be analyzed in just 30 seconds – and provides a unique spectral signature on a computer screen, like a unique fingerprint, according to the mineral and organic matter composition of the soil sample. Once you have calibrated the method using a library of diverse soils, the cost per sample is greatly reduced.

Through the African Soil Information Service project (AfSIS), WLE has set up Soil-Plant Spectral Diagnostics Labs in ten African countries, and is helping Ethiopia, Ghana, Nigeria, and Tanzania conduct their first-ever soil health baseline, using this groundbreaking soil testing technique.

Over the last 6 years, AfSIS has built the most comprehensive soil sample database to date for Africa, with over 28,000 sampling locations. AfSIS gives accurate localized predictions of soil properties relevant for agricultural extension, such as organic carbon content and pH, as well as nutrient content, like total nitrogen or extractable potassium.

A sampling of maps being used to produce the first generation of continent-wide soil property maps. 

Africasoils.net.

Development agencies have started using the benefits of these new soil testing methods for better planning. WLE is assisting the World Bank to improve soil health data monitoring in the household socio-economic panel surveys in Ethiopia and Uganda as part of the Living Standards Measurement Study (LSMS). Comparing farmer knowledge of soil quality – often based on soil color and texture - and data from spectral soil tests, a study in Ethiopia has shown that farmers are unable to discriminate between “poor” and “good” soil fertility levels, and are often overly optimistic about soil quality. The infrared method is seen as a feasible way to bring about better decision-making for future farming programs. WLE has also helped set up a soil lab for the NGO One Acre Fund in rural Kenya, which performs thousands of spectral soil tests per month, enabling them to assess the long-term impact of their agricultural programs.

WLE researchers have also developed the Soil Organic Carbon (SOC) Application, which calculates the quantity of organic carbon captured in a specific soil profile. The SOC App is able to quantify the impact of soil conserving practices on sequestration over time, and at different scales. This open-access application will help decision-makers assess to what degree  land restoration efforts would contribute to carbon sequestration and climate change mitigation.

From more accurate soil health mapping to better farming

Some countries, like Ethiopia, have started investing in these new soil information systems because they understand that they could boost their agricultural production. The Ethiopian Soil Information System (EthioSIS), with the support of AfSIS, has been able to analyze agricultural soils in 570 districts to date, revealing significant deficiencies in nitrogen, phosphorus, potassium, sulfur, zinc, boron and copper. A Soil Fertility Status and Fertilizer Recommendation Atlas for 136 woredas (districts) has just been released, with visual maps for each woreda. These show thing like where potash fertilizer use is recommended, or where application of lime could help rehabilitate acidic soils.

It is estimated that if accurate fertilization recommendations were implemented at full scale, farmers’ yields would increase by about 65 per cent on average. A large-scale extension scheme now needs to be rolled out. In order to start convincing the 4.5 million smallholder farmers to adopt these recommendations, 40,000 fertilizer demonstrations have already been carried out in collaboration with development partners and the Regional Bureaus of Agriculture.

With the right prescription to restore the soil health of their fields, farmers can reap more bountiful harvests while helping to reduce carbon emissions in the atmosphere.

Acknowledgments

• DAI 2: Information Systems for Land, Water & Ecosystems - Soil Information Systems: Lead center: the World Agroforestry Center (ICRAF) with the following partners: Earth Institute, University of Columbia, Columbia Global Centers- Africa, Ministry of Agriculture, Nigeria, Ministry of Agriculture, Food Security, and Cooperatives, Ministry of Agriculture, Ghana, Ethiopia Soil Information Service, Agricultural Transformation Agency, Ministry of Agriculture, Ethiopia, India Council of Agricultural Research.
• African Soil Information Service (AfSIS): AfSIS is funded by the Bill and Melinda Gates Foundation and is supported by close scientific, operational and implementation partnerships with the Agriculture and Food Security Center (AgCenter) and the Center for International Earth Science Information Network (CIESIN) at the Earth Institute of Columbia University, the World Agroforestry Centre (ICRAF), and ISRIC – World Soil Information.
• Soil Organic Carbon (SOC) Application: led by CIAT under WLE, with support from Deutsche Gesellschaft für Internationale Zusammenarbeit, GIZ.
• Ethiopia Land and Soil Experimental Research (LASER) project under the World Bank’s Living Standards Measurement Study (LSMS) Methodological Validation Program funded by UK Aid: implemented by the Central Statistical Agency of Ethiopia and the World Agroforestry Center (ICRAF).