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.

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 tbi@decolab.org! If you want to join our mailing list and hear more from us, look for the following link: http://www.decolab.org/tbi/mailinglist.php.

Additional information

Our web page: http://www.decolab.org/tbi/

Our mailing list: http://www.decolab.org/tbi/mailinglist.php

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.


How many years of four-years politics yet?

Antonio Jordán
Lorena M. Zavala

University of Seville, Spain

Recently, we and some members of our research group visited a burned area in Montellano (province of Sevilla, Southern Spain) to plan some field experiments. This area was affected by a wildfire during last August 2012.
The fire affected between 70 and 80 ha of a hardly accessible area, characterized by a pine dense forest, shallow soils and steep slopes. Originally an arson fire due to local struggles, fire quickly climbed the north face of the mountain, reached the top and moved down the southern slope in hours. The area is used by residents for recreative activities.

Continue reading

Fire and ants

Paulo Pereira
Mykolas Romeris University, Vilnius, Lithuania

Ants are amazing creatures, not only for the recognized work capacity, but also due their great resilience to disturbance. They are considered ecosystem engineers and have an important impact on soil physical (e.g moisture, porosity), chemical (organic matter accumulation and redistribution and CO2 emissions) and biological properties. Ants build a complex network of tunnels and galleries in soil subsurface transporting sediments, with important impacts on soil erosion, and nutrients. These changes have implications on favourable conditions for plant germination. Continue reading

Can field wetlands trap eroding agricultural soil?

Dr Clare Deasy
Senior Research Associate
Lancaster Environment Centre, Lancaster University

A shallow field wetland located in a field corner on a mixed agricultural farm in Cumbria, UK, showing the wetland collecting surface runoff eroding soil from agricultural fields during a storm event.

Field wetlands are small constructed wetlands designed to trap eroded soil and associated pollutants from diffuse sources including field surface runoff and runoff from drains and ditches. Data from ten UK trial field wetlands created on unproductive agricultural land, in field corners and in buffer strips, indicate that field wetlands can be very effective at sediment and nutrient trapping.  Continue reading

What grows in wetland soil after drought?

Dr Lyndsey Vivian                                                                                                                            CSIRO, Canberra, Australia

Soil dug up from a wetland at Barmah Forest, Victoria, Australia. Here we are running an experiment to see what plant species have viable seed in the soil, after many years of drought. Some seeds only germinate if they think there’s a flood. We have filled the green trays with water to emulate a flood.

This photo was originally posted at See My Soil