Adaptation: Field of Action Soils

freshly ploughed fieldClick to enlarge
The different impacts of climate change affect soil characteristics and functions.
Source: joeEsco/photocase.com

Soil, with all its functions necessary for life, is an important non-renewable resource and, as a CO2 storage, an indispensable part of climate protection efforts. Adaptation measures must be aimed at protecting the soil from erosion, humus loss and other climate-related risks.

Ecosystem Measures

Measures of the ecosystem approach consist of protecting soils in a sustainable manner and preserving them in their natural state. Above all, sustainable and good agricultural practice is important in this context as agriculture represents the largest intervention in the balace of nature in terms of area. More than half of the area of Germany is used for agriculture.

Agriculture can contribute to soil protection through a climate-sensitive selection of varieties and species as well as adapted crop rotations, sowing dates, fertilisation, soil cultivation and tilling methods. For example, site-adapted crop rotation can ensure continuous soil cover throughout the year. Permanently ploughless conservation tillage preserves the natural soil structure and reduces the risk of erosion and compaction.

So far, there is no comprehensive erosion monitoring in Germany. Soil erosion monitoring, which is carried out on existing permanent observation plots (BDF) in individual federal states, is the only transnational measuring network for long-term recording of soil erosion in Germany. Its procedure and intensity are not uniform. Despite the lack of representative monitoring data, hazard potentials can be derived at the federal level by means of modelling. (Source: Monitoringbericht 2019)

The preservation of the humus content is particularly important. Humus is an important storage medium for nutrients and water and reduces the summer dryness of the soil. In addition, the soil stores carbon in humus, thereby reducing the amount of the climate-relevant greenhouse gas carbon dioxide in the atmosphere.

Land use changes and unsustainable use and management contribute to soils losing their carbon sink function and becoming a source of greenhouse gases. Moor soils are "hot spots", because the storage and release potential from organic soils is significantly higher and more persistent than from mineral soils. In addition, the hydromorphic mineral soils (soils characterised by groundwater: gleye, marshlands, alluvial soils) are also of particular relevance. A decisive contribution to both climate protection and soil conservation is to maintain, restore or sustainably improve the C sink function of soils as far as possible.

The preservation of moor soils and grassland is of great relevance for climate protection. Grassland uprooting releases a considerable amount of the carbon stored in the soil into the atmosphere in the form of greenhouse gases. In addition, for soils under grassland, both the risks of dehydration and of soil erosion by water and wind are significantly reduced. During heavy rainfall, rainwater can penetrate better into permanently overgrown grassland soils.

Grassland area in Germany decreased between 1991 and 2013 and has been increasing slightly since 2014. Since 2015, EU directives have made it mandatory to maintain permanent grassland, according to which the conversion of permanent grassland into arable land is generally only permitted after approval and in most cases only possible if new permanent grassland is established elsewhere. In areas designated under the Fauna-Flora-Habitat Directive (FFH areas), permanent grassland is even strictly prohibited from being converted or altered. However, newly created grassland does not have the same importance for climate protection or biodiversity, as it is usually species-poor.

Technical measures

Vehicles and machinery in agriculture, forestry and the construction industry have become increasingly powerful and, in most cases, heavier in recent decades. If vehicles or machines roll over floors, weight-dependent pressure is generated. If the pressure under the tires is greater than the stability of the soil, the soil particles are compressed more tightly. This compaction of the soil impacts the soil quality. On the one hand, agricultural yields are reduced however, on the other, the living conditions for soil organisms deteriorate, and the infiltration of rainwater into the soil can be restricted.

Vehicles and equipment that drive over open ground can be adapted in such a way that the total mass and the specific surface pressure are better distributed, and thus the load-bearing capacity of the ground is less strained. One possible measure is to use wide tires with low internal pressure and large contact area. In addition, the use of lighter machines with less payload mass is beneficial for soil protection.

The stability of the soil can also be improved by reducing the working depth and intensity. Therefore, ploughless loosening of the soil not only helps to maintain intact soil life, but also preserve a stable soil structure. In addition, ploughless tillage reduces fuel costs and helps prevent soil erosion as protective crop residues remain on the soil surface.

Appropriate adaptation measures must be taken at both regional and local levels.

Legal, political and management measures

In order to protect the soil, it is important to focus soil protection policy more strongly on soil-related climate protection and adaptation measures. This also includes taking greater account of the climate protection function of soils in legislation and in planning and approval procedures.

Numerous specific measures can strengthen soil protection. Here are some selected examples:

  • Protection of soils, in particular those with a very high C storage capacity or high C reserves from overbuilding within the framework of planning and approval procedures
  • Sustainable use of arable land, in particular through: ensuring a balanced humus balance; preventing the loss of organic matter due to water and wind erosion; preventing soil damage compaction.
  • Grassland areas can be permanently protected and preserved as CO2 reservoirs by including them in appropriate funding programs and legal regulations.
  • The reduction of land consumption in settlement and traffic development, as well as land unsealing contribute to keeping soils free for rainwater infiltration and reducing the risk of flooding.
  • The unsealing and recultivation contributes to an improved urban climate.
  • Land reserves in built-up areas can contribute to maintaining the biomass production potential and the CO2 storage function of soils.
  • Areas with little or no vegetation can be converted into compensation areas for construction projects or into urban green spaces.
  • Land use planning should secure peatlands and, if possible, regenerate drained peatlands.

Since adaptation strategies require a sound information base, further knowledge must be gained on the possibilities of climate adaptation in the soil sector. In order to be able to assess the consequences of climate change on soil functions, information on soil, land use and regional climate changes is also necessary. Climate change related soil monitoring could be an important source of information here. Against this background, the 2nd DAS Progress Report states that a climate impact soil monitoring network should be implemented and established in the long term. The aim of this instrument is the nationwide collection, monitoring and documentation of the actual state of soils in Germany, as well as the changes resulting from climate change. To this end, the network will provide easy access to soil-related measurement data for users in science and administration and will network and coordinate the activities of measuring point operators and users.

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