Soils are one of the planet’s most precious non-renewable resources. They are essential for the production of food, animal feed, shelter and energy. They store and filter water, recycle nutrients, provide a buffer against floods, sequester carbon and host one-quarter of the Earth’s biodiversity.
Yet in many parts of the world – and especially in poorer countries – soils are in danger, threatened by urbanization, deforestation, poor agricultural practices, pollution and overgrazing, leaving them bare, degraded and unproductive.
World Soil Day highlights the importance of soil and the need to use it sustainably. The event has been marked annually since the International Union of Soil Sciences (IUSS) passed a resolution in 2002 proposing December 5 as World Soil Day. To raise awareness further, FAO’s Global Soil Partnership has declared the year 2015 as the UN International Year of Soils. In the past few weeks, the research and development community has met to discuss the most pressing issues relating to soil and landscape protection at Global Soil Week and the Global Landscapes Forum.
“Soil. It’s like the air we breathe – we can’t live without it. It provides our food, cleans our water, supports our ecosystems and livelihoods, and even gives us lifesaving medicines,” wrote CGIAR researcher Deborah Bossio in a recent blog post. She leads the International Center for Tropical Agriculture (CIAT)’s Soils Research Area and the CGIAR Research Program on Water, Land and Ecosystems (WLE)’s Rainfed Portfolio.
In a blog to underscore the crucial role played by soil in food security and sustainable land management, WLE delivers some of the bad news. Soils are disappearing fast. Estimates are that the world is losing 24 billion tons of fertile soil each year. That is the equivalent of 3.4 tons lost every year for every person on the planet. It takes millennia to form just a few centimeters of soil.
In Africa alone, land degradation affects 67% of agricultural land, with about 490 million hectares showing erosion and declining vegetation. Over the past 50 years, land and soil degradation have reduced crop yields and the agricultural share of gross domestic product by 9-10%. In recent decades, land degradation has accelerated over 36 times its historical rate. The cost of land degradation is currently about US$490 billion per year. Land degradation is a major driver of poverty, preventing smallholder farmers from making agriculture viable and profitable.
Agriculture is a prime cause of land degradation and soil depletion. According to the CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS), soils in agro-ecosystems lose 25 to 75 percent of their organic carbon during the initial conversion of ecosystems from natural to agricultural, and due to such soil degradation processes as erosion, salinization and nutrient depletion.
Fortunately, there is some good news too. The first piece is that there is much that can be done – and the work is already under way. Restoring degraded landscapes, starting with soils, is a major focus of WLE’s Rainfed research portfolio, which is working to develop site-specific strategies to restore ecosystem services in landscapes.
As a cross-cutting issue, work on soil is a fundamental part of CGIAR’s global research agenda. In common with all the CGIAR Research Programs (CRPs), the WLE program has adopted a new approach, which shifts the focus on agricultural development away from simply boosting productivity towards sustainable intensification, which enhances productivity, contributes to global sustainability and the eradication of poverty and increases resilience. Addressing soil health and land degradation plays a key role in this strategy and several CRPs are working with partners to tackle these issues on a longer term basis.
In one concrete example of how CRP research is being applied to produce practical solutions, a WLE blog reports on how licorice is being used as a potential low-cost option to rehabilitate soil stripped of its fertility because of high salinity in the harsh climate of northwestern Uzbekistan. Licorice is a salt-tolerant plant that thrives in tough conditions and also helps to regenerate soil.
Properly managed soil offers massive scope for climate change mitigation. Sustainable land use and management practices increase the amount of carbon in soils. Carbon-rich soil means higher agricultural output and greater resilience to extreme climatic events. According to figures reported by CCAFS, increasing the soil carbon pool by 1 tonne of carbon hectare per year [3.7 tCO2e/ha/yr] in developing countries can enhance agronomic production by 32 ± 11 million metric tonnes per year (Mt/yr) of cereals and pulses and 9 ± 2 Mt/yr of roots and tubers. Increasing carbon in soils can also offset fossil fuel emissions, thereby mitigating climate change. Soils in croplands, grazing lands and rangelands can store an estimated 1,500 to 4,500 million metric tonnes of carbon dioxide equivalent (MtCO2e) per year.
A recent study by CGIAR Consortium member the Center for International Forestry Research (CIFOR) on soil organic carbon’s role in improving agricultural productivity in West Africa, describes how innovative tree-planting techniques are helping farmers to increase valuable carbon levels. The simple tree planting methods, which help to retain soil moisture and fertilizer around seedlings, include the demi lune and cordon piere techniques, which are commonly used in the Sahel.
“Soil carbon provides important support to food security by maintaining soil fertility for agricultural productivity,” said Johnson Nkem, author of the report. He explains that high levels of soil carbon improve soil quality by increasing levels of nitrogen, phosphorus and potassium in the soil. They also help to stop minerals from leaching after heavy rainfall and improve soil’s physical structure, protecting it from wind and water erosion. A 1 mg increase of soil carbon on degraded cropland can increase crop yields by 20 to 40 kg per hectare for wheat, 10 to 20 kg per hectare for maize and 0.5 to 1 kg per hectare for cowpea, says the CIFOR report.
Using a participatory approach that brings together scientific and local knowledge, another CGIAR Consortium member, World Agroforestry Centre (ICRAF), is working with farmers to determine locally appropriate soil management options, including the integration of trees and shrubs into farms, to address commonly encountered soil problems like erosion, compaction and acidity. The work also seeks to strengthen local institutions that support rural communities in making decisions related to soil management.
Monitoring and diagnosis
More knowledge about soil is crucial for boosting agricultural production in a sustainable manner and making systems more climate resilient. Advances in research have led to the development of new tools to diagnose and monitor degradation. ICRAF’s Land Health program has scored a number of successes in developing new techniques to monitor the health of soils, especially in Africa, using infra-red technology, X-rays, and laser. As part of its work, the program has helped set up infra-red spectral diagnostic labs in 10 African countries. One of the techniques developed by ICRAF scientists and partners — called total X-ray fluorescence spectroscopy (TXRF) – makes it possible to make a quick, affordable and accurate analysis of concentrations of most of major and trace elements in soils, paving the way for better land use and environmental planning. Also from ICRAF comes news of work on soil diagnosis by the Africa Soil Information Service (AfSIS), of which the World Agroforestry Centre is a partner. Through AfSIS, detailed digital maps, databases and soil assessments have been produced to help scientists and policymakers make site-specific recommendations for boosting food production. The AfSIS project has a goal of assessing soils across sub-Saharan Africa, as well as a soil health surveillance system, so that national research and extension providers can plan their strategies and farmers can make the best sustainable use of their land.
Scientists from CIAT are in the forefront of soil research. In sub-Saharan Africa, they are carrying out innovative strategic research into integrated soil fertility management (ISFM) — which aims to boost small-farm productivity through combinations of improved germplasm (especially of legumes), organic and inorganic fertilizers and better agronomic practices. They are also exploring sustainable land management, with a focus on generating soil information and mapping soil properties and ecosystem health at landscape scale. In Latin America and the Caribbean, work is focusing on improving smallholder systems and developing the region’s extensive new agricultural lands in environmentally friendly ways. In Southeast Asia, the CGIAR Research Center is working to maintain the natural resource base and improving soil health in the more remote upland areas and major farming systems of the Greater Mekong subregion.
In the global spotlight
The crucial – but often undervalued – role played by soil in improved food security and sustainable intensification is attracting growing international recognition. A WLE blog reports that, in the outcome document of Rio+20, the international community identified the need to take action on land and soils and committed to aiming for a land-degradation-neutral world (LDNW). The conference also set in motion a process to develop universal Sustainable Development Goals (SDGs), which herald an opportunity to put soils and land on the global sustainable development agenda.
In a blog to mark the start of Global Soil Week in October this year, World Bank rural development specialist Maurizio Guadagni claimed that soils are the forgotten ecosystem service, when in fact they are the key to food security, biodiversity protection and especially to mitigating and adapting to climate change. Guadagni is connected to the new Bridging Agriculture and Conservation Initiative, launched in Brazil in July by CGIAR Consortium member Bioversity International, together with global partners. On the steppes of Kazakhstan in central Asia, the world’s seventh largest wheat exporter, he has recently helped persuade many farmers to adopt no-till farming. “It has increased yields there by up to 40 per cent during drought years and 30 per cent at other times,” he reports.
Earlier this year, CGIAR researcher Caity Peterson, a visiting researcher working with CCAFS, went to Ghana to see what farmers there are doing to tackle soil health issues in a climate smart manner. Ghana has one of the most nutrient-deficient soils in sub-Saharan Africa, but farmers are using simple and effective techniques to address the problems. By planting crops on ridges, they are enabling plant residues to accumulate in contours where they later break down, providing a nutrient boost to the soil, as well as slowing the flow of water. Other strategies include allowing crop residues to remain in the field to decompose, rather than burning them, and preparing animal manure as compost before applying it, so that it does not burn young plants. Composting also reduces the amount of nitrous oxide and methane emitted when manure is applied to the soil.
Farmers in Lawra district, who Peterson watched reaping the rewards of their new approach, use the phrase “soil power” to describe the gains they make from these climate-smart practices. As World Soil Day gets under way, that simple slogan says it all.
World Soil Day
Global Soil Partnership
Support World Soil Day and the International Year of Soils 2015 (FAO video)
International Union of Soil Sciences (IUSS)
Africa Soil Information Service (AfSIS)
Global Soil Week
Global Landscapes Forum
Bridging Agriculture and Conservation Initiative – CGIAR Consortium
A month on land: Restoring soils and landscapes – CGIAR Consortium
Soil knowledge vital to boosting agricultural production – CGIAR Consortium
New X-ray technology to reveal the makeup of Africa soils – CGIAR Consortium
The answer lies in the soil – CGIAR Consortium
Soil – CGIAR Consortium
Soil: carbon sinks – CGIAR Consortium
Sweet Solution? Licorice could reclaim degraded lands – CGIAR Consortium
New tree-planting and water-use methods boost soil carbon to aid food security in Africa – CGIAR Consortium
Food security starts from the ground up – CGIAR Consortium
People power equals soil power in Ghana’s Upper West – CGIAR Consortium
Photo credit: P.Casier/CGIAR