Soil science and policy challenges

Sarah Connors, EGU Science Policy Fellow
Antonio Jordán, University of Seville


Discussions during the 5th International Conference of Fire Effects on Soil Properties in the O’Brien Centre for Science, Dublin, Ireland (2015), by Antonio Jordán. Distributed by Imaggeo.

Soil is often considered as the skin of the Earth and is located at the interface between the lithosphere, hydrosphere, atmosphere and biosphere. Soil is the physical and nutritional support for living organisms in emerged areas. Continue reading

Special issue on geo-environmental effects of wildfires

When fire runs. Credit: A. Jordán. Click to see the original picture and data at Imaggeo.

Noemí Lana-Renault Monreal
University of La Rioja, Spain

We are glad to announce that the Special Issue on “Geo-environmental effects of wildfires”, which has been recently published by Cuadernos de Investigación Geográfica (volume 40 (2), 2014). This Special Issue aims at bringing together the key impacts of wildfires on runoff, soil properties and erosion, and plant biomass changes.

Cuadernos de Investigación Geográfica
Cuadernos de Investigación Geográfica.

Some contributions to this Special Issue include field measurements and lab experiments. Keesstra et al. (2014), investigated in the lab the fire effects on a Redzina soil and suggested that water repellency and protection by ash were factors to consider in assessing the erosion susceptibility of a burnt forest soil; Velasco & Úbeda (2014) analyzed soil aggregate stability after a forest fire that occurred in 1994, and Moya et al. (2014), studied the post fire forest management in relation to biomass recovery and carbon stock on burnt areas. Other contributions to this Special Issue synthesized the state-of-the-art in several related topics, especially the effect of fire on soil properties (Zavala et al., 2014), soil erodibility in Galicia (Benito et al., 2014), soil organic matter (de la Rosa et al., 2014) and soil erosion and runoff in Portugal (Prats et al., 2014). Additionally, the contribution by Herrera & Chuvieco (2014) highlights the importance of estimating fuel moisture content by hyperspectral measurements for fire risk assessment. The last contribution of this Special Issue (Domíneguez et al., 2014) assesses media coverage of wildfires and critically discusses the lack of scientific communication about the nature of wildfires in Mediterranean ecosystems.
All the articles are freely accessible here (see the table of contents below).

About the journal

Cuadernos de Investigación Geográfica is issued twice a year and includes original research and review papers on all aspects of physical geography and environmental sciences. All papers are subject to full peer review. This journal has been in publication uninterruptedly since 1975. It is indexed in Scopus since 2009.

Editors of the Special Issue

Artemi Cerdá, Universitat de Valéncia
José Arnáez Vadillo, Universidad de La Rioja
Noemí Lana-Renault, Universidad de La Rioja
José M. García-Ruiz, Instituto Pirenaico de Ecología (CSIC)

Table of contents

A dark future sprouting from sealed soil

A view of Quito (Ecuador). Credit: Martin Mergili. Click on the image to see the original picture and details in Imaggeo.

Every year in Europe, soils covering an area larger than the city of Berlin are lost to urban sprawl and transport infrastructure. This unsustainable trend threatens the availability of fertile soils and groundwater reservoirs for future generations. A new report made public today by the European Commission recommends a three-tiered approach focused on limiting the progression of soil sealing, mitigating its effects and compensating valuable soil losses by action in other areas.

Environment: Soil sealing in the EU threatens the availability of ecosystem services. European Commission – IP/11/624   23/05/2011

You live on sealed soil

Look out your window. If you do not live isolated in the countryside, it will be difficult that most of which you can see is not sealed floor. Most land around you is covered by buildings or pavement. It is normal, you live in a town or a village. There is much more space out there! Is there much space out there?

Decay. Credit: Marcel Van Oijen. Click on the image to see the original picture and details in Imaggeo.

Soil sealing occurs when it is covered with impervious surfaces such as asphalt or concrete. These materials are necessary for construction of buildings and road materials, but its use implies the disappearance of agricultural resources and food production, significant changes in the hydrological processes at catchment scales as well as the loss the most important soil functions as habitat and biological support, biomass production, gene pool, sink of greenhouse gases, filtration and transformation of substances and protection of groundwater and the food chain …

Organic farming. Credit: Kristof Van Oost. Click on the image to see the original picture and details in Imaggeo.
Soil products. Credit: Artemi Cerdà. Click on the image to see the original picture and details in Imaggeo.

Even in cities, unsealed floor areas are necessary. because rain water can not flow through paved surfaces, and the ability of the sewerage system is overloaded.

A problem linked to social inequality

The rapid occupation of land for buildings has become one of the most important environmental problems. Due to migration from rural areas to the big cities and the intense changes of use from the second half of the twentieth century until now, the area of ​​land devoted to agriculture or natural vegetation is declining. And the reasons are obvious: the private economic benefit obtained from construction is much higher than from farming. Besides food products can be imported from other countries. But … is this a sustainable policy? How long?

Just one example: in Andalusia, where I live, land consumption per capita has increased by 4 in the last 50 years, from 87 m2 in 1956 to more than 337 m2 in 2007. Although causes vary from one region to another (industrial and commercial growth, infrastructure construction, mining activities, landfills, etc.), in all cases urban expansion is the main cause of soil sealing.

Rural roads change the landscape. Credit: Artemi Cerdà. Click on the image to see the original picture and details in Imaggeo.

And it’s not just a problem in the south of Europe. In small countries like Austria, only one third of the land can be used for construction. But urban and industrial expansion continues (the Viennese population grows at a rate of 20,000 people per year), so that in many parts of the country there is not much space and urban planning should be seriously analyzed.

Land abandonment is a key factor of Mediterranean Landscapes. Credit: Artemi Cerdà. Click on the image to see the original picture and details in Imaggeo.

In the EU, At least 275 ha of soil per day were lost, amounting to 1,000 km² per year Between 1990 and 2000, although this trend has been reduced to 252 ha per day in recent years, but the rate of land consumption is still worrying. Between 2000 and 2006, the EU average increase in artificial areas was 3%, with increases attaining 14% in Ireland and Cyprus and 15% in Spain (read more here).

May we get rid of soil sealing?

Obviously, people need to be fed. And for that we need transport infrastructures and consequent soil sealing. We also need infrastructures for the processing of raw materials. As a colleague says, “processes generate structures“. Therefore, we can not do without soil sealing. But we can achieve a balance.

How to? Discovering the causes

The poor generally have access only to areas that have higher risk for health and income generation. And they generally lack the resources to reduce the exposure to the risk or to invest in alleviating the causes of such risk. Environmental degradation therefore can affect the health and nutrition status of the poor and lower their productivity. This can happen both directly through, for example, lower yields per unit of labor or land because of reduced soil quality, and indirectly through the reduced physical capacity of labor to produce because of malnutrition and poor health. Even in cases where the poor are healthy labor productivity can be low due to increased time being allocated to less-productive activities such as fuel wood collection and away from agriculture and other income generating activities.

Consultative Group on International Agricultural Research. CGIAR research priorities for marginal lands. Document No.:SDR/TAC:IAR/99/12.

Zooming in community. Credit: Veilo Coviello. Click on the image to see the original picture and details in Imaggeo.

In current systems, urban population, for which most of these infrastructures are intended, is mostly concentrated in points far from the sources of production. The rural population migrates to cities due to low access to education, health care and, above all, low incomes and job expectations.

Ploughing in Central rift valley, Ethiopia. Credit: Saskia Keesstra. Click on the image to see the original picture and details in Imaggeo.

Although the consequences of this migration are not as severe (they are) in the so-called First World, the urban agglomeration does not solve these problems. More, it contributes to create large pockets of poverty in the periphery of cities. Here we have an interesting political issue. Are we heading towards a future of smart cities for the ruling class surrounded by belts of hunger, poverty and insecurity?

Getting crowded. Credit: Albin Hammerle. Click on the image to see the original picture and details in Imaggeo.

Read more


This post has been also published in the EGU Blog Network.

Soil colors – what more could you want?

Nuno Simões
University of Algarve, Portugal

Nuno Simões (before combing). Meet Nuno at EGU2014-SSS2.7.

We can easily see that soil color varies from one site to another, with depth, with topographic position and composition. Even color may be light brown in one side of the road and dark brown in the other. Whether for scientific purposes, or just curious, you study the colorimetric interesting variations.

Why does soil color change?

The soil color varies due to the characteristics of substances that form it. These variations can be caused by several factors, as, for example, soil humidity (the wetter the soil is, the darker it gets), soluble salts, sand and carbonates (light colors), iron oxides (red colors), organic matter (dark colors), etc.

How can soil color be measured?

Soil color is usually described using the Munsell color scale, which is a very good tool for soil taxonomy, for example. But there are other interesting methods that can be used depending in our purposes. The method I am presenting here uses the ColortronTM spectrophotometer, a device that measures the color at the surface of solids and transfers it to the ColorshopTM program. This spectrophotometer can use various color scales such as CIE Lab, CIE RGB, CIE XYZ, among other scales.

A study case

This example is a study conducted in Boca do Rio (Algarve, southwestern Portugal), which consisted of the identification of sedimentary deposits of the 1755 tsunami in the area. We used the CIE Lab color model which, according Nederbragt and Thurow (2004), is the most suitable for paleoenvironmental studies. CIE Lab aims to mimic the way the human eye understands the color and is divided into three parameters, L*, a* and b*. This color space is organized in a three-dimensional model, where L* is the vertical axis and is defined by lightness (Figure 1). The maximum brightness is L* = 100, which represents a perfect diffuser (reflecting white) and the minimum is 0, which represents black. Value of L* is conditioned by organic matter and carbonate contents (Helmke et al., 2002), as well as water content. In contrast, a* and b* represent the chromaticity and do not show numerical limits. The value of a* is positive when it tends towards red, and negative when it tends towards green. Similarly, b* is positive when it tends to yellow and negative when it tends to blue.

Figure 1. CIE Lab scale.
Figure 1. CIE Lab scale.

How to?

Usually, three replicated color measurements are carried out with the Colortron and average values are used as representative.

Figure 2. Sediment sampling.
Figure 2. Sediment sampling.
Figure 3. Sediment samples prepared to start measuring (left) and Colotron device (right).
Figure 3. Sediment samples prepared to start measuring (left) and Colotron device (right).

After obtaining and processing data (Figures 2 and 3), results can be plotted to obtain brightness and chromaticity graphics (Figure 4).

Figure 4. Brightness (CIE L) and blue-to-yellow chromacity (CIE b) from bulk sediment and siliciclastic fractions (Font et al., 2013).
Figure 4. Brightness (CIE L) and blue-to-yellow chromacity (CIE b) from bulk sediment and siliciclastic fractions (Font et al., 2013).

Figure 5 show the relation between b* value of the siliciclastic fraction and the average particle size. Relations between data obtained at the base of the deposit and the C unit and at the top with A unit were found. Note that the tsunami deposit layer is located between the units A and C.

Figure 5. Relation between average particle size (mean AS) of siliciclastic fraction and parameter b* (Font et al., 2013).
Figure 5. Relation between average particle size (mean AS) of siliciclastic fraction and parameter b* (Font et al., 2013).

Another way to confirm these results is to use the obtained values as a scale for an image editor, in this case, the CIE Lab color model. Thus it is possible to build a profile with the color corresponding to the sampled places (Figure. 6).

Figure 6. Color of a portion of an horizontal profile of the Arrifes beach, southern Portugal.
Figure 6. Color of a portion of an horizontal profile of the Arrifes beach, southern Portugal.


I want to thank Cristina Veiga-Pires and Eric Font for their help with the identification of tsunami deposits in southern Portugal.


Font, E., Veiga-Pires. C.C., Pozo, M., Nave, S., Costas, S., Ruiz Muñoz, F., Abad, M., Simões, N., Duarte S. 2013. Benchmarks and sedimentary source(s) of the 1755 Lisbon Tsunami deposit at Boca do Rio estuary. Marine Geology 343;1-14. DOI: 10.1016/j.margeo.2013.06.008.

Helmke, J.P., Schulf, M., Bauch, H.A. 2002. Sediment color record from the Northeast Atlantic reveals patterns of millenial-scale climate variability durin the past 500 000 years. Quaternary Research 57: 49-57. DOI: 10.1006/qres.2001.2289.

Nederbragt, A.J. Thurow, J.W. 2004. Digital sediment colour analysis as a method to obtain high resolution climate proxys records. In Francus, P. (Ed.), Image Analysis, Sediments and Paleoenvironments. Developments in Paleoenvironmental Research, Vol. 7, Chapter 3. Kluwer Academic Publishers. Pp. 105-124. DOI: 10.1007/1-4020-2122-4_6.


This post has been published simultaneously in the EGU Blog Network.

Will drinking tea get us thinking about soils? Yes, but only if you help us spread the word!

Taru Lehtinen
PhD candidate at the Faculty of Life and Environmental Sciences, University of Iceland

Meet Taru at EGU2014 in sessions SSS10.3 and SSS10.8.

The Tea Bag Index Project wants to create a global map on decomposition with the help of citizen scientists. We use teabags to collect vital information on the global carbon cycle. With our protocol (see our web page and our article: Keuskamp et al., 2013), citizen scientists worldwide can collect data without much effort or instrumentation.

Tea Bag Index Project developed a simple and cheap method, which anyone can use to measure decomposition in the soil, simply by burying teabags. Tea Bag Index Project want to gather data points from all over the globe through the involvement of citizen scientists.

Two main questions to be answered with the data gathered:

  1. How do environmental conditions determine the speed of decomposition?
  2. How do environmental conditions determine how much is broken down?

Eventually, a global soil map of decomposition will be created that can be used for educational purposes and to make current climate models even more accurate.

What is about?

Decomposition (the decay of organic material) is a critical process for life on earth. Through decomposition, nutrients become available for plants and soil organisms to use as a food source in their metabolism and growth. When plant material decomposes, it loses weight and releases the greenhouse gas carbon dioxide (CO2) into the atmosphere. In cold environments, breakdown is slower than in warm environments, meaning more carbon is stored in the soil and less CO2 is released. Factors like moisture content, acidity, or nutrient content of soils can also influence how quickly plant material decomposes


For better insight into global CO2 emissions from soils it is important to know more about decomposition in those different soils. Such an insight is important to improve climate models that show CO2 fluxes. To clarify the picture of global decomposition, we need a lot of information on different soil characteristics and related decomposition rates around the world. Large efforts have been taken to create a soil map of the world; however, predictions on the relations between soil an decomposition are often imprecise. It would be a great improvement if we could actually measure decomposition (rate and degree) globally.

Tea Bag Index Project developed a simple and cheap method to measure decomposition rate and degree. By burying everyday tea bags.

As tea is plant material, the weight loss of nylon teabags over time represents the decomposition of the plant material within an ecosystem. After three months buried in the soil of interest, the bags are dug up, dried and weighed. By burying two types of tea with different decomposition rates, we obtain information on how much and how fast plant material is broken down.

The importance of this research

Efforts have already been taken to map global soil and climate conditions; however an index for decomposition rate is still missing. Predictions of decomposition used in climate models are often imprecise.

The idea is to use the Tea Bag Index to collect data from around the world to feed databases in the global soil map, and to get as many citizen scientists as possible involved. This crowdsourcing approach will strengthen the dataset; due to the power-by-numbers principle; and it will increase awareness of soil science at the same time.

Soil receives very little attention in media coverage of environmental issues. Tea Bag Index Project specifically aims to involve school classes and youth groups as those have shown the highest response and most reliable data so far.

We hope to get as many school classes and youth groups as possible to get involved in the project! Tea Bag Index Project would be grateful for your help in spreading the word about this new method, and your support in making a global decomposition map reality!

If you want to discuss during EGU2014 send an email to Taru Lehtinen, and feel free to send comments to! If you want to join our mailing list and hear more from us, look for the following link:

Additional information

Our web page:

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Know more

Keuskamp JA, Dingemans BJJ, Lehtinen T, Sarneel JM, Hefting MM. 2013. Tea Bag Index: a novel approach to collect uniform decomposition data across ecosystems. Methods in Ecology and Evolution 4, 1070-1075. DOI: 10.1111/2041-210X.12097.

Lehtinen T, Gísladóttir G, van Leeuwen JP, Bloem J, Steffens M, Ragnarsdóttir KV. 2014. Do aggregate stability and soil organic matter content increase following organic inputs? Geophysical Research Abstracts 16, EGU2014-905-1.

Lehtinen T, Schlatter N, Baumgarten A, Bechini L, Krüger J, Grignani C, Zavattaro L, Costamagna C, Spiegel H. 2014. Effect of crop residue incorporation on soil organic carbon (SOC) and greenhouse gas (GHG) emissions in European agricultural soils. Geophysical Research Abstracts 16, EGU2014-10278.


This post has been simultaneously published in the EGU Blog Network.


Working for the recovery of burned soils

Fire is a natural agent that occurs in most terrestrial ecosystems. In Mediterranean areas, for example, fire is a natural agent that has contributed to shape the history of vegetation, soils, and ultimately, the landscape we know today. Also, since ancient times, men have also used fire as a tool for the management of ecosystems. As a result, the Mediterranean vegetation has developed mechanisms of adaptation to fire, but Man has contributed to the intense transformation of the original forest systems in crops, pastures and meadows and dehesas from the fifteenth century to encourage farming, sylvopastoral use of forests, and human supply.

Prescribed burn in Portugal. Photo by Vicky Arcenegui, University Miguel Hernández, Spain.
Prescribed burn in Portugal. Photo by Vicky Arcenegui, University Miguel Hernández, Spain.

In countries like Spain, the concentration of population in urban areas that began in the second half of the 20th century has led to a shift away from rural areas and declining crop and livestock pressure. The abandonment of traditional rural labors contributed to forget an efficient management of agricultural and forest resources, such as maintenance of terraces on the slopes, care of roads or forest clearing. All this, coupled with the pressures of tourism, the expansion of urban areas and other social reasons, has led to a large increase in the number and damage caused by forest fires during the 1960s, 1970s and 1980s. Since 1990, the number of forest fires has increased progressively, although affecting a lower annual total. In recent years, though the number of forest fires has declined high intensity fires are still occurring. High intensity fires occur under certain environmental conditions (high temperatures, wind and low humidity of vegetation and soil), but also due to a management of the forest environment that favors the spread of fire.

In the context of global change, scientists expect the number of high intensity wildfires increase, as well as the severity of its impact on the environment, the productive capacity and natural resources. For these reasons, scientists who study the impact of fire on soils have participated in the development of practice guidelines for the management planning burned soils that facilitate managers to decide when, where and how to act.

Soil scientists and firefighters during a prescribed burn in Sevilla. Photo by Antonio Jordán, University of Seville.
Soil scientists and firefighters during a prescribed burn in Sevilla. Photo by Antonio Jordán, University of Seville.

According to the Spanish Network Forest Fire Effects on Soils, a concern that is necessary to transfer the decision-makers that it is not always necessary to act in the post -fire, and that in many cases, both the vegetation and the soil can recover themselves in relatively short periods of time. Also, that actions cannot be the same on all systems, and the planning and management of burned areas should be based on local characteristics of the environment.

Good forest management practices should be based on scientific research. Lots of money have been used for fight against forest fires, but just to prevention activities, and scarcely for the study of their impact on soil, water and vegetation. The knowledge of the effects of fire on soil properties and the proposing and use of impact factors becomes essential when performing management decisions, restoration or prevention of the areas affected by fire.

To this end, scientists from Galicia (Forest Research Centre Lourizán, Institute of Agrobiological Research from Galicia, University of Santiago de Compostela and University of Vigo) have developed the first guide for urgent action planning against soil erosion in fire-affected forest areas. This initiative has been supported by the Spanish Government and FEDER funds of the European Union.

Guide for urgent actions against soil erosion in burned forest areas
Guide for urgent actions against soil erosion in burned forest areas

The first part of the text studies the risk of erosion and soil hydrological response after fire in Galicia, where soils, vegetation and climate are very different from neighbor regions. The second part details the urgent treatments to combat erosion risk in the post -fire, proposing methodologies for assessing the severity of fire impacts on soil and vegetation, and recommends a guide for urgent decision-making.

We hope this work, a collaboration of scientists deep and managers, help the recovery of degraded areas in a region hard hit by the effects of fire.

This post was also published simultaneously in the EGU Blog Network.