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Soil at JRC > SOER2010 (State of Environment Report 2010) > Section 2. State and Trends

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Section 0. Summary

Section 1. Introduction

Section 2. State and Trends

Section 3. Impacts

Section 4. Outlook 2020

Section 5. Response

Glossary/supporting information

SOER 2010

Determining the state and trends of soil functions

Soil functions occur under our feet and often involve microbial activity and chemical reactions. Subtle variations in soil characteristics over short distances can significantly affect how the soil operates due to soil complexity, spatial variability and scale issues. This can lead to uncertainties in making wide-ranging representative statements on the state of soil in general

In some instances, the degradation of soil functions can be seen at the land surface. Examples include poor crop yields due to poor soil management or pools of standing water at the entrance to fields where the traffic of heavy agricultural machinery has led to subsoil compaction and impeded drainage. However, in most cases, evidence for the state of soil functions has to be collected painstakingly through intensive field sampling and laboratory analysis. The development of effective indicators for different soil functions is a challenge.

Another issue that hampers pan-European assessment of soil state is the lack of a legal requirement to collect such information in a harmonised manner or even at all. While most European countries have mapped the soils on their territory that are used for agricultural Another issue that hampers pan-European assessment of soil state is the lack of a legal requirement to collect such information in a harmonised manner or even at all. While most European countries have mapped the soils on their territory that are used for agricultural and forest production, many of these surveys are now several decades old, not updated and may not contain the data required to answer current questions such as their potential as carbon sinks, the impacts of pollutants on soil micro-fauna, the leaching of phosphorus due to over-fertilisation or the state of environmental functions. Some countries have detailed and wide-ranging soil monitoring networks which measure a number of parameters relating to soil quality. However, many of these networks reflect national priorities and standards, making the comparison of their results with those of other countries difficult. Many countries have no provision for the systematic collection of soil data.

Consequently, there is a difficulty in applying a bottom-up approach of collating reports from the individual countries to derive a harmonised evaluation for Europe. While there are increasing examples of soil-function maps at the local level, pan-European assessments are rare. As a result, many of the appraisals of soil functions at the European level are provided largely through models using assumptions about the ability of specific soil types to provide certain functions. In a simplistic example, sandy soils allow the easy drainage of surface water but crops grown on these soils can suffer during periods of drought as the water storage capacity is low. The converse is generally true for clay soils. However, all such models are simplifications of the real world, are data intensive and are still being refined.

Photo 2.1: Soils provide a myriad of life-critical, environmental and socio-economic functions: the most recognised is the production of food, fibre and wood. Without fertile soil, life as we know it would not be possible. © Erika Micheli

Determining the state and trends of threats to soil

Widespread soil degradation, leading to a decline in the ability of soil to carry out its ecosystem services, is caused largely by non-sustainable uses of the land over a long time span. This has also marked local, regional, European and global impacts. Soil degradation contributes to food shortages, higher commodity prices, desertification and ecosystem destruction. Society has a duty to ensure that the soil resources within their territories are managed appropriately and sustainably. The character of the major threats to soil has not changed significantly since the last assessment (EEA, 2005a). The following sections outline the state and trends of the main soil degradation processes in Europe and show that, while the situation is variable, many soil degradation processes are accelerating in many parts of Europe (EEA, 2005b), often exacerbated by inappropriate human activities and widely varying approaches to tackling degradation processes.

Soil organic matter is essentially derived from residual plant and animal material, transformed (humified) by microbes and decomposed under the influence of temperature, moisture and ambient soil conditions. Soil organic matter (SOM) plays a major role in maintaining soil functions because of its influence on soil structure and stability, water retention, soil biodiversity, and as a source of plant nutrients. The primary constituent of SOM is soil organic carbon [link 4].

Erosion is the wearing away of the land surface by water [link 6] and wind [link 7], primarily due to inappropriate land management, deforestation, overgrazing, forest fires and construction activities. Erosion rates are very sensitive to climate, land use, soil texture, slope, vegetation cover and rainfall patterns as well as to detailed conservation practice at field level. With the very slow rate of soil formation, any soil loss of more than 1 t ha-1 yr-1 can be considered as irreversible within a time span of 50–100 years (Huber et al., 2008) [link 8].

Soil compaction occurs when soil is subjected to pressure from the use of heavy machinery or dense stocking with grazing animals, especially under wet conditions [link 11].

Soil sealing happens when agricultural, forest or other rural land is taken into the built environment. Sealing also occurs within existing urban areas through construction on residual inner-city green zones.

Salt accumulation in soil, commonly referred to as salinisation, is a world-wide degradation process. While naturally saline soils exist in certain parts of Europe, the main concern is the increase in salt content in the soils resulting from human interventions such as inappropriate irrigation practices, use of salt-rich irrigation water and/or poor drainage conditions. Locally, the use of salt for de-icing can be an issue. The primary method of controlling soil salinity is to use excess water to flush the salts from the soil (in most cases where salinisation is a problem, this must inevitably be done with precious, high quality irrigation water) [link 12].

Acidification describes the loss of base cations (e.g. calcium, magnesium, potassium, sodium) through leaching and replacement by acidic elements, mainly soluble aluminium and iron complexes [Link 13]. Acidification is always accompanied by a decrease in a soil's capacity to neutralise acid, a process which is naturally irreversible when compared to human lifespans. In addition, the geochemical reaction rates of buffering substances in the soil are a crucial factor determining how much of the acidifying compounds are neutralized over a certain period. Acidifying substances in the atmosphere can have natural sources such as volcanism, however, the most significant ones in the context of this assessment are those that are due to anthropogenic emissions, mainly the result of fossil fuel combustion (e.g. in power plants, industry and traffic) and due to intensive agricultural activities (emissions of ammonia, NH3). Emissions of sulphur dioxide (SO2) and nitrogen oxides (NOX) to the atmosphere increase the natural acidity of rainwater, snow or hail. This is due to the formation of sulphuric and nitric acid (H2SO4, HNO3), both being strong acids. Ammonia contributes to the formation of particulate matter in the air, including ammonium (NH4 -). After deposition to ecosystems, the conversion of NH4 - to either amino acids or nitrate (NO3-) is an acidification process.

Furthermore, forestry and agriculture (due to biomass harvest) can lead to ecosystem acidification processes in soils. Such conditions can be found in the heathlands of north-western Europe where land management practices over centuries have led to soil acidification and erosion.

Soil biodiversity: Soil biota play many fundamental roles in delivering key ecosystem goods and services, such as releasing nutrients from SOM, forming and maintaining soil structure and contributing to water storage and transfer in soil (Lavelle and Spain, 2001). Soil biodiversity is generally defined as the variability of living organisms in soil and the ecological complexes of which they are part; this includes diversity within species, between species and of ecosystems (UN, 1992).

Desertification: Prolonged droughts and more irregular precipitation, combined with unsustainable use of water and agricultural practices, could lead to desertification, defined by the United Nations Convention to Combat Desertification (UNCCD) (UN, 1994) as 'land degradation in arid, semi-arid and dry sub-humid areas resulting from various factors, including climatic variations and human activities'. The most recent terminology adopted by the UNCCD includes 'Desertification, Land Degradation and Drought'. This reflects the widespread endorsement of the Convention also by countries that do not have drylands within their national territories. Within the EU, the following Member States consider themselves affected by desertification and are included in the Annex V of the UNCCD: Cyprus, Greece, Hungary, Italy, Latvia, Malta, Portugal, Slovakia, Slovenia and Spain (UN, 2001).

Landslides are the gravitational movement of a mass of rock, earth or debris down a slope (Cruden, 1991) [link 16]

Soil contamination: It is important to distinguish between local soil contamination (the result of intensive industrial activities or waste disposal [Link 18]) and diffuse soil contamination covering large areas [Link 19] (see also the SOER 2010 Consumption and the environment assessment (EEA, 2010d)).

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