Soils Help to Combat and Adapt to Climate Change

2015 International Year of Soils

Healthy soils provide the largest store of terrestrial carbon. When managed sustainably, soils can play an important role in climate change mitigation by storing carbon (carbon sequestration) and decreasing greenhouse gas emissions in the atmosphere. Conversely, if soils are managed poorly or cultivated through unsustainable agricultural practices, soil carbon can be released into the atmosphere in the form of carbon dioxide, which can contribute to climate change. The steady conversion of grassland and forestland to cropland and grazing lands over the past several centuries has resulted in historic losses of soil carbon worldwide. However, by restoring degraded soils and adopting soil conservation practices, there is major potential to decrease the emission of greenhouse gases from agriculture, enhance carbon sequestration and build resilience to climate change.

The carbon cycle is the exchange of carbon (in various forms) between the atmosphere, ocean, terrestrial biosphere and geological deposits. Most of the carbon dioxide in the atmosphere comes from biological reactions that take place in the soil. Carbon sequestration occurs when carbon from the atmosphere is absorbed and stored in the soil. This is an important function because the more carbon that is stored in the soil, the less carbon dioxide there will be in the atmosphere contributing to climate change.

Climate change represents a serious threat to global food security, not least because of its effects on soils. Changes in temperature and rainfall patterns can have a great impact on the organic matter and processes that take place in our soils, as well as the plants and crops that grow from them. In order to meet the related challenges of global food security and climate change, agriculture and land management practices must undergo fundamental transformations. Improved agriculture and soil management practices that increase soil organic carbon, such as afro-ecology, organic farming, conservation agriculture and agroforestry, bring multiple benefits. They produce fertile soils that are rich in organic matter (carbon), keep soil surfaces vegetated, require fewer chemical inputs, and promote crop rotations and biodiversity. These soils are also less susceptible to erosion and desertification, and will maintain vital ecosystem services such as the hydrological and nutrient cycles, which are essential to maintaining and increasing food production. The Food and Agriculture Organization of the United Nations (FAO) also promotes a unified approach, know as Climate-Smart Agriculture (CSA), to develop the technical, policy and investment conditions that support its member countries in achieving food security under climate change. CSA practices sustainability increase productivity and resilience to climate change (adaptation), while reducing and removing greenhouse gases whenever possible (mitigation).

Soils Store and Filter Water

2015 International Year of Soils

Functional soils play a key role in the supply of clean water and resilience to floods and drought. Water infiltration through soil traps pollutants and prevents them from leaching into the groundwater. Moreover, the soil captures and stores water, making it available for absorption by crops, and thus minimizing surface evaporation and maximizing water use efficiency and productivity. Healthy soils with a high organic matter content have the capacity to store large amounts of water. This is beneficial not only during droughts when soil moisture is crucial to plant growth, but also during heavy rainfall because the soil reduces flooding and run-off by slowing the release of water into streams. Healthy soils are therefore crucial for maintaining food production and clean groundwater supply, while also contribution to resilience and disaster risk reduction.

The amount or percentage of water in the soil (by weight) is generally referred to as soil moisture content. The maximum amount of available water that a soil can retain (the available water capacity) will vary depending on the soil's texture, organic matter content, rooting depth and structure. Soil organic matter is particularly important in that it can retain about 20 times its weight of water. By implementing sustainable agricultural practices, farmers can influence the structure and organic matter content of the soil to improve its water infiltration and retention.

Water is the "lifeblood" of agricultural practice worldwide--improved soil moisture management is critical for sustainable food production and water supply. Reduction of a soil's capacity to accept, retain, release and transmit water reduces its productivity, whether of crops, pasture species, shrubs or trees. The great challenge for the coming decades will be the talk of increasing food production with less water, particularly in countries with limited water and land resources. In order to minimize the impact of drought on food security, soil needs to capture the rainwater that falls on it, store as much of that water as possible for future plant use, and allow plant roots to penetrate and proliferate.

Problems with or constraints on one or several of these conditions cause soil moisture to be a major limiting factor for crop growth. In fact, poor crop yields are more often related to an insufficiency of soil moisture rather than an insufficiency of rainfall. Poor and unsustainable land management techniques also decrease soil moisture content. Overcultivation, overgrazing and deforestation put great strain on soil and water resources by reducing fertile topsoil and vegetation cover, and lead to greater dependence on irrigated cropping. Meeting food scrutiny targets requires the implementation of sustainable agricultural policies that ensure improved soil quality and water retention. As most smallholder farmers in developing countries are reliant on rainfed agriculture, improved soil moisture optimization and management is crucial.

A number of sustainable agricultural and land management practices can help to improve soil moisture retention capacity, including:

• Residue covers, cover crops and mulching protect the soil surface, improve water infiltration rates, and reduce both erosion and evaporation, thus improving soil moisture compared to bare soils, even under low rainfall.
• Conservation tillage is a general term which has been defined as "whatever sequence of tillage operations that reduces the losses of soil and water, when compared to conventional tillage"
• Zero-tillage, which is the practice of leaving residue of the previous season's crops on farmland, can increase water infiltration while reducing evaporation as well as wind and water erosion.
• Conservation agriculture employs the three principles of minimal soil disturbance, permanent soil cover and crop rotations to improve soil conditions, reduce land degradation and boost yields.
• Use of deep-rooting, drought-resistant, or less water-demanding crops can help preserve soil moisture and improve food security
• Capture of runoff from adjacent lands can lengthen the duration of soil moisture availability

Soils are the Foundation for Vegetation

2015 International Year of Soils

Healthy soils are crucial for ensuring the continued growth of natural and managed vegetation, providing feed, fiber, fuel, medicinal products and other ecosystem services such as climate regulation and oxygen production. Soils and vegetation have a reciprocal relationship. Fertile soil encourages plant growth by providing plants with nutrients, acting as a water holding tank, and serving as the substrate to which plants anchor their roots. In return, vegetation, tree cover and forests prevent soil degradation and desertification by stabilizing the soil, maintaining water and nutrient cycling, and reducing water and wind erosion. As global economic growth and demographic shifts increase the demand for vegetation, animal feed and vegetation by products such as wood, soils are put under tremendous pressure and their risk of degradation increases greatly. Managing vegetation sustainably--whether in forests, pastures or grasslands--will boost its benefits, including timber, fodder and food, in a way that meets society's needs while conserving and maintaining the soil for the benefit of present and future generations. The sustainable use of goods and services from vegetation and the development of agroforestry systems and crop-livestock systems also have the potential to contribute to poverty reduction, making the rural poor less vulnerable to the impacts of land degradation and desertification.

Soils and Crops

The symbiotic relationship between soils and vegetation is most apparent in the agricultural sector: food security and nutrition rely on healthy soils. The nutrient content of a plant's tissues is directly related to the nutrient content of the soils and its ability to exchange nutrients and water with the plant's roots. Similarly, plant growth is influenced to soil physical properties such as texture, structure and permeability. However, the practices of intensive agriculture, monoculture and deep tillage put soil health at risk by depleting the soil of nutrients, causing soil pollution, altering soil structure and water retention capacity, fostering soil erosion and decreasing soil biodiversity, which is the basis of soil biological activities. Soil degradation in agricultural systems is directly related to the overuse of fertilizers and pesticides, the removal of the crop residues from the soil surface and the use of heavy machinery. Additionally, nutrient depletion is related to the absence of the fallow period in intensive agricultural systems and to the practice of monoculture, which deplete soil nutrients due to static nutrient demand. Therefore, crop rotation is critical to preserving and eventually improving soil health. Crops protect soil against soil erosion agents, improve soil structure by rooting, and enrich soil nutrients by providing organic matter and establishing symbiotic relationships with soil bacteria. Sustainable soil management is thus critically important to addressing the growing food demand caused by population growth.

Key Facts

• 75-90 percent of people in developing countries depend on natural products as their only or main source of medicine.
• The use of solid biofuels--including wood--is predicted to grow by 300 percent between 2007 and 2030.
• About 20 percent of the world's pastures and rangelands, with more than 70 percent of the rangelands in dry areas, have been degraded to some extent.
• Forests provide livelihoods for more than a billion people and are vital for conservation of biodiversity, energy supply, and soil and water protection.

Soil's Preservation is Essential for Food Security

2015 International Year of the Soils

Soil is a finite resource, meaning its loss and degradation is not recoverable within a human lifespan. As a core component of land resources, agricultural development and ecological sustainability, it is the basis for food, feed, fuel, and fiber production and for many critical ecosystem services. It is therefore a highly valuable natural resource, yet it is often overlooked. The natural area of productive soils is limited--it is under increasing pressure of intensification and competing uses for cropping, forestry, pasture/rangeland and urbanization, and to satisfy demands of the growing population for food and energy production and raw materials extraction. Soils need to be recognized and valued for their productive capacities as well as their contribution to food security and the maintenance of key ecosystem services.

Soil degradation is caused by unsustainable land uses and management practices, and climate extremes that result from various social, economic and governance drivers. Today, 33 percent of land is moderately to highly degraded due to erosion, salinization, compaction, acidification and chemical pollution of soils. The current rate of soil degradation threatens the capacity of future generations to meet their most basic needs. Current demographic trends and projected growth in global population (to exceed 9 billion by 2050) are estimated to result in a 60 percent increase in demand for food, feed and fiber by 2050. There is little opportunity for expansion in the agricultural area, except in some parts of Africa and South America. Much of the additional available land is not suitable for agriculture, and the ecological, social and economic costs of bringing it into production will be very high. Sustainable management of the world's agricultural soils and sustainable production have therefore become imperative for reversing the trend of solid degradation and ensuring current and future global food security.

Key Facts:

• By 2050, agricultural production must increase by 60 percent globally, and by almost 100 percent in developing countries in order to meet food demand alone.
• 33 percent of soil is moderately to highly degraded due to erosion, nutrient depletion, acidification, salinization, compassion and chemical pollution.
• A shortage of any one of the 15 nutrients required for plan growth can limit crop yield.
• In most developing countries, there is little room for expansion of arable land: virtually no spare land is available in South Asia and the Near East/North Africa.
• Where land is available, in sub-Saharan Africa and Latin American, more than 70 percent suffers from soil and terrain constraints.
• More efficient use of water, reduced use of pesticides and improvements in soil health can lead to average crop yield increases of 79 percent.

How can we save our soils?

The sustainable use and management of soils is linked to many different areas of sustainable development--poverty reduction, hunger eradication, economic growth and environmental protection. Promoting the sustainable management of soils can contribute to healthy soils and thus to the effort of  eradicating hunger and food insecurity and to stable ecosystems. There is an urgent need to stop land degradation in its various forms and establish frameworks for sustainable soil management systems. The Intergovernmental Technical Panel on Soils of the Global Soil Partnership recommends the following actions:

• Provide suitable technologies, sustainable and inclusive policies, effective extension programs and sound education systems so that more is produced with less;
• Include soil protection and reclamation and sustainable land management projects in the current emerging markets that provide an economic value to those actions that produce ecosystem services;
• Recognize the increasing need to preserve soils and have governments make corresponding investments;
• Promote management practices for climate change adaption and mitigation, and resilience to changing weather patterns and extremes;
• Promote strong regulations and effective control by governments in order to limit the accumulation of contaminants beyond established thresholds for human health and eventually to remediate contaminated soils;
• Increase the area under sustainable soil management practices, enhance the restoration of degraded soils, and promote "sustainable production intensification" through adapted biological resources, increasing soil fertility, water use efficiency, ensuring sustainable use of inputs and recycling of agricultural by-products;
• Support the development of national soil information systems to assist decision-making on sustainable land and natural resource uses;
• Increase investment in sustainable soil management by overcoming obstacles including tenure security and user rights, access to knowledge and financial services;
• Strengthen the implementation of capacity development and education programs on sustainable soil management.

A Healthy Soil is a Living Soil

2015 International Year of Soils

Biological diversity or 'biodiversity' is described as "the variability among living organisms from all sources, whether terrestrial, aquatic or marine." It includes the diversity within species (genetic diversity), between species (organism diversity) and of ecosystems (ecological diversity). Soil is one of nature's most complex ecosystems and one of the most diverse habitats on earth: it contains a myriad of different organisms, which interact and contribute to the global cycles that make all life possible. Nowhere in nature are species so densely packed as in soil communities; however, this biodiversity is little known as it is underground and largely invisible to the human eye.

Soil Biodiversity and Agriculture

Our agricultural systems exert an important influence on soil organisms, including their activities and their biodiversity. Clearing forested land or grassland for cultivation affects the soil environment and drastically reduces the number and species of soil organisms. A reduction in the number of plant species with different rooting systems, in the quantity and quality of plant residues, or in soil organic matter content limits the range of habitats and foods for soil organisms. While the use of external inputs, particularly inorganic fertilizers and pesticides, can overcome some soil constraints to crop production, the overuse or mis-use of afro-chemicals has resulted in environmental degradation, particularly of soil and water recourses. The quality and health of soils largely determine agricultural production and sustainability, environmental quality and, as a consequence of both, has bearing on plant, animal and human health. Improving soil biodiversity is vital to ensuring soil health and further food and nutrition security. Agricultural systems and afro-ecological practices that dedicate great care to nurturing soil biodiversity, such as organic farming, zero-tillage, crop rotation and conservation agriculture, can sustainably increase farm productivity without degrading the soil and water resources.

What do soil microorganisms do?

In both natural and afto-ecosystmes, soil organisms are responsible for performing vital functions in the soil ecosystem which have direct interaction with the biological, atmospheric and hydrological systems. Soil organisms act as the primary agents of nutrient cycling, regulating the dynamics of soil organic matter, soil carbon sequestration and greenhouse gas emissions, modifying soil physical structure and water regimes, enhancing the amount and efficiency of nutrient acquisition by the vegetation through mutualistic relationships, and enhancing plant health. These services are essential to the functioning of natural ecosystems and constitute an important resource for the sustainable management of agricultural systems

The Soil Food Web
When diverse soil organisms interact with one another and with the plants and animals in the ecosystem, they form a complex web of ecological activity called the soil food web. The resilience of the food web in inextricably linked to the biodiversity within the soil.

Healthy Soils are the Basis for Healthy Food Production

2015 International Year of Soils

The most widely recognized function of soil is its support for food production. It is the foundation for agriculture and the medium in which nearly all food-producing plants grow. In fact, it is estimated that 95% of our food is directly or indirectly produced on our soils. Healthy soils supply the essential nutrients, water, oxygen and root support that our food-producing plants need to grow and flourish. Soils also serve as a buffer to protect delicate plant roots from drastic fluctuations in temperature. 

Soil health has been defined as the capacity of soil to function as a living system. Healthy soils maintain a diverse community of soil organisms that help to control plant disease, insect and weed pests, form beneficial symbiotic associations with plant roots, recycle essential plant nutrients, improve soil structure with positive effects for soil water and nutrient holding capacity, and ultimately improve crop production. A healthy soil also contributes to mitigating climate change by maintaining or increasing its carbon content.

Key Soil Facts:

• 95% of our food is directly or indirectly produced on our soils.
• A shortage of any one of the 15 nutrients required for plant growth can limit crop yield.
• By 2050, agricultural production must increase by 60% globally--and by almost 100% in developing countries--in order to meet food demand alone.
• It can take up to 1,000 years to form one centimeter of soil.
• Sustainable soil management could produce up to 58% more food.

Food availability relies on soils: nutritious and good quality food and animal fodder can only be produced if our soils are healthy. A healthy living soil is therefore a crucial ally to food security and nutrition. In the past 50 years, advances in agricultural technology led to a quantum leap in food production and bolstered world food security. However, in many countries this intensive crop production has depleted the soil, jeopardizing our ability to maintain production in these areas in the future. With a global population that is projected to exceed 9 billion by 2050, compounded by competition for land and water resources and the impact of climate change, our current and future food security hinges on our ability to increase yields and food quality using the soils that are already under production today. Numerous and diverse farming approaches promote the sustainable management of soils with the goal of improving productivity, for instance: organic farming, conservation agriculture, and zero tillage farming.


Organic farming is agricultural production without the use of synthetic chemicals or genetically modified organisms, growth regulators, and livestock feed additives. It also emphasizes a holistic farm management approach, where rotations and animals play an integral role to the system. Soil fertility is the cornerstone of organic management. Because organic farmers do not use synthetic nutrients to restore degraded soil, they must concentrate on building and maintaining soil fertility primarily through their basic farming practices.

Conservation agriculture practices have significantly improved soil conditions, reduced land degradation and boosted yields in many parts of the world by following three principles: minimal soil disturbance, permanent soil cover and crop rotations. To be sustainable in the long term, the loss of organic matter in any agricultural system must never exceed the rate of soil formation. In most agro-ecosystems, that is not possible if the soil is mechanically disturbed. Therefore, one of the tenets of conservation agriculture is limiting the use of mechanical soil disturbance, or tilling, in the farming process.

Zero tillage is one of a set of techniques used in conservation agriculture Essentially, it maintains a permanent or semi-permanent organic soil cover (e.g. a growing crop or dead mulch) that protects the soil from sun, rain and wind and allows soil micro- organisms and fauna to take on the task of “tilling” and soil nutrient balancing - natural processes that are disturbed by mechanical tillage.