As one of the executive editors of Solid Earth, one of my main duties is to keep up the journal’s reputation and a high quality of published articles. For a manuscript to be considered as a candidate for publication, it is necessary to fall within the scope of the journal. But, in my opinion, it also needs to show “new science”: innovation in the methods or approaches, sound results and conclusions interesting for a wide audience (which does not need to be simply formed by specialized scientists). Continue reading
There is hardly a subject in all nature, of which the majority of people has so unclear terms and which has hitherto been so completely misunderstood, as the soil on which they walk.
Soil is often considered as the skin of the Earth and is located at the interface between the lithosphere, hydrosphere, atmosphere and biosphere. Air, water, rock and living beings interact to form soil, which, in turn, is the physical and nutritional support for living organisms in emerged areas. Currently, we define soil is an open system that temporarily stores the necessary resources for living organisms. The availability of these resources (water, energy, mineral nutrients, etc.) depends on the intensity and speed of exchange processes between soil and the rest of compartments of ecological systems.
But the concept of soil has been modified in accordance to the increasing understanding of its components and the relations among them. During centuries, soil was considered not more than dirt on rocks, when not simply one of the strata in geological profiles. See, for example, the following statement: “That all the earthy part of soil consists of minute fragments of rock does not require argument, or need proof, but inspection merely to determine it. We have only to place specimens under the magnifier and their rocky origin will become manifest” (Eaton and Beck, 1820). Continue reading
As part of the activities of the International Year of Soils, FAO has published the following Soil Facts. Contribute with your comments!
La Trobe University
AgriBio Centre for AgriBioscience
Melbourne, VIC, Australia
Sandy soils in Western Australia are bad soils for growing plants due to their poor nutrients and water holding capacity (see an example in Figure 1). In general, these soils are water repellent, which leads to land degradation by increasing soil erosion risk and run-off rates. Nevertheless, these soils may be improved by clay addition, which leads to increase soil organic carbon content (Franzluebbers et al. 1996). Several ways have been used to increase soil organic carbon content in soils: i) no-tillage systems, ii) addition of bio char , iii) organic amendments or fertilizer addition and iv) switch to perennial plants. But there is another potential method for enhancing soil organic carbon storage in soils which has received little attention: mixing of isolated clay with sandy soils. Continue reading
University of Seville, Sevilla, Spain
Currently, the complexity of soil microbial ecology on soil systems is a hot topic in the environmental sciences, since the scientific community has achieved a deep knowledge of the relevance of microorganisms in soil processes. After several decades of study of the effects of wildfires on soils, one of the main conclusions is that soil microbial populations are very sensitive to fire, which allows us to use them as a tool to assess the impact of fire on ecosystems.
Fly, thought, on golden wings,
go alight on the cliffs, on the hills,
where the sweet airs of our
native soil smell soft and mild!
Chorus of the Hebrew slaves, Nabucco
Have you ever noticed the smell of rain? Why does wet soil smell so good?
The smell of wet soil plants oils released into the soil during dry periods is due. These substances accumulate in the soil and mix with geosmin, produced and released by several groups of bacteria, including actinobacteria (eg, Streptomyces) and cyanobacteria. Geosmine (from Greek “geo”, earth, and “osmin”, smell) is a bicyclic alcohol derivative of decain, and was firstly described in the 1960s (Gerber and Lechevalier, 1965). When it rains, these chemicals are released into the atmosphere and cause a special smell which is known in English as petrichor (Greek “petros”, stone, and “ikhôr” liquid flowing through the veins of the gods). Continue reading
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?
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 …
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.
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.
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.
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.
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?
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This post has been also published in the EGU Blog Network.