Dossier

Monitoring: National Soil Surveys in Forests and Agricultural Land

Nicole Wellbrock, Christopher Poeplau | 02.05.2022

WO Institute of Forest Ecosystems

AK Institute of Climate-Smart Agriculture

Soils provide plants with nutrients and water, they are a habitat for a variety of organisms and affect our climate. Only those who know the condition of their soils can use them sustainably and protect their diverse functions. The status of soils in Germany is therefore regularly examined.

Die Bodenfarbe in den einzelnen Horizonten lässt sich mithilfe der Munsell-Farbtabelle genau bestimmen. — The soil color in the individual horizons can be precisely determined with the help of the Munsell Colour Table. It provides information about the soil type.

In a nationwide German approach, the Thünen Institute investigates agricultural and forest soils at more than 5,000 locations. The scientists take into account regional differences and small-scale characteristics of soils as well as the diversity of their use.

Soil processes take place slowly. Therefore, regularly recurring surveys are necessary to obtain meaningful results.

The first National Forest Soil Inventory was carried out for the first time from 1987 to 1993. The second inventory was conducted from 2006 to 2008. The third inventory began in March 2022 and is scheduled to be completed by the end of 2024.

Germany's agricultural soils were also surveyed for the first time from 2011 to 2018 with the National Soil Inventory in Agriculture. A repetition will take place from 2023 to 2027.

A key finding of these inventories: in Germany, the current organic carbon storage capacity of soil (0-90 cm) and vegetation in forests and agricultural land together is around 5 billion tons.

As part of the nationwide inventories of forest and agricultural soils, scientists look inside the soils: they determine the soil type, carbon content, structure and storage density of the soils, as well as many other parameters. They also investigate the processes that take place in the soil. In this way, knowledge about soil as a resource is constantly being expanded in a large number of individual investigations.

Inventory design of the forest soil survey

The nationwide forest soil survey is a federal/state cooperation. The respective federal states collect the data in the field and analyze samples in the laboratory according to uniform methods. The federal government has mandated the Thünen Institute with the coordination and nationwide evaluation. The systematic sampling network covers the entire forest area of Germany. About 1,900 inventory points were sampled in a grid of 8 by 8 kilometers.

Sampling is carried out at 8 satellites, each located at a distance of 10 meters from the mid-point. The distance corresponds to 45 degrees starting in north direction. The humus layer is sampled as well as different depth levels in the mineral soil (0-5, 5-10,10-30, 30-60 and 60-90 centimeters). All samples of one depth level are combined into composite samples.

At the inventory points, the participating teams of the federal states conducted a comprehensive soil profile approach. This was done on a soil profile – which is a vertical section from the surface through the soil – at the inventory point. Teams of experts determined more than 66 parameters on the soil profile and in the field, amongst otherssoil type, humus content, groundwater level and parent rock.

In addition to soil, other studies are conducted on nutritional status, ground vegetation, dead wood, and stocking. A sub-sample in a grid of 16 by 16 kilometers is part of the forest condition survey. A total of around 443 laboratory parameters were examined on more than 50,000 samples of humus, mineral soil, leafs and needles.

Inventory design of the agricultural soil survey

The first nationwide agricultural soil survey with focus on stocks of soil organic matter was conducted from 2011 to 2018 by the Thünen Institute of Climate-Smart Agriculture. In a grid of 8 by 8 kilometers, a total of 3,104 sampling points under arable land, grassland and special crops were investigated with the active support of the farmers.

A profile pit of one cubic meter was excavated at each of the sampling points. In addition, eight soil cores were taken. The profile pits were precisely measured by GPS and additionally marked with a subsoil marker, allowing them to be precisely located for repeat samplings.

Soil mapping with recording of soil typological parameters and sampling was carried out by experienced soil scientists of the Thünen Institute. Soil samples were collected and analyzed from depth levels 0-10, 10-30, 30-50, 50-70, and 70-100 centimeters. A questionnaire provided information on the management of the last ten years.

In the years 2023 to 2027, the agricultural soil survey will now be repeated. The primary objective is to identify possible changes in the stocks of soil organic matter and their causes. Compared to the first inventory, there are some changes in the sampling scheme and the parameter list: In the future, four small profile pits will be opened around each initial soil profile and sampled at depths of 0-10, 10-30, and 30-50 centimeters. Soil properties below 50 centimeters will be considered stable at ten-year intervals and therefore will not be re-determined initially. Static soil properties such as texture and stone content will also not be re-determined. First interim results will be published at the end of 2025.

Gley-Vega kommt häufig in Augebieten vor und wird vor allem als Grünland zur Weidehaltung genutzt. — Gley-Vega kommt häufig in Augebieten vor und wird vor allem als Grünland zur Weidehaltung genutzt: Durch regelmäßige Überflutungen lagern sich nach und nach Sedimente ab – auf dem Foto zeigt sich ein ehemaliges Flussbett mit Kieselsteinen.

Braunerden speichern viel Wasser und eignen sich gut zum Anbau von Getreide und Kartoffeln. In Deutschland ist diese Bodenart sehr weit verbreitet...

...auch als Waldboden. Wenn das Ausgangsmaterial wie auf diesem Foto sehr steinig ist, eignet sich Braunerde besser für den Waldbau als für den Ackerbau.

Ranker sind Waldböden, die vor allem an den Hängen der Mittelgebirge verbreitet sind. — Ranker sind Waldböden, die vor allem an den Hängen der Mittelgebirge verbreitet sind: Die Bäume verankern sich meist in Fugen und Klüften des Gesteins.

Der Podsol ist ein typischer Waldboden in Deutschland. Weit verbreitet ist dieser Boden unter anderem in Norddeutschland, wo er sehr sandig und sauer ist und deshalb ein häufiger Standort für Kiefern.

Pseudogley eignet sich als Standort für Baumarten wie Stieleiche, Hainbuche und Esche. — Pseudogley, der „Boden des Jahres 2015“, eignet sich als Standort für Baumarten wie Stieleiche, Hainbuche und Esche. Zwar ist er nährstoffreich, wegen seiner Bodendichte bildet er bei häufigen Niederschlägen aber Stauwasser, weshalb er als Ackerfläche nur mäßig geeignet ist.

Schwarzerden sind die ertragreichsten und fruchtbarsten Böden in Deutschland. Der Pflughorizont geht in einen stark humusangereicherten Horizont über, der Bodenlebewesen wie Rügenwürmern, Mäusen und Maulwürfen zu verdanken ist.

Tonböden werden oft als Grünland genutzt. Die Nutzung als Ackerboden bietet nur kurze Zeitfenster zur Bodenbearbeitung. — Tonböden werden oft als Grünland genutzt. Die Nutzung als Ackerboden bietet nur kurze Zeitfenster zur Bodenbearbeitung: Im nassen Zustand bleiben gerne mal Fahrzeuge stecken, und im trockenen Zustand werden die sogenannten Minutenböden schnell steinhart.

Der Treposol ist ein Tiefumbruchboden. Zur besseren landwirtschaftlichen Nutzung wurden diese ertragsarmen Böden früher mit einem großen Dampfpflug einmalig umgebrochen, sodass die ursprünglichen Horizonte quergestellt sind. Treposole gibt es häufig in Nordwestdeutschland.

Rigosole wurden im Gegensatz zu Treposolen mehrfach tief umgebrochen, um auf steinreichen Böden oder Hängen Kulturflächen für den Weinanbau zu gewinnen. Der sogenannte Weinbergsboden war 2014 „Boden des Jahres“.

Der Plaggenesch ist in den Niederlanden, in Westfalen, Niedersachsen, Schleswig-Holstein und Dänemark zu finden. Über Jahrhunderte wurde dort Boden gestochen und zur Unterlage in Ställe verbracht. Später wurden die mit Tierkot angereicherten Plaggen wieder auf die Felder ausgebracht – und karge Sandböden somit verbessert.

Publications National Forest Soil Inventory

Thünen Report 43
Dynamik und räumliche Muster forstlicher Standorte in Deutschland – Ergebnisse der Bodenzustandserhebung im Wald 2006 bis 2008 (558 p. German)

Status and Dynamics of Forests in Germany Results of the National Forest Monitoring

Publications National Soil Inventory in Agriculture

Thünen Report 64
Landwirtschaftlich genutzte Böden in Deutschland – Ergebnisse der Bodenzustandserhebung (248 p. German)

Publication of the main results

Publication list

Data of the BZE Landwirtschaft

Video

German agricultural soil inventory

A total of about 3100 soil sample were taken nationwide within the context of the German agricultural soil inventory by Thünen Institute. What takes place on the field and what happens to the soil samples in the laboratory? This video tells us the story.

Expertise

Against acid soil: What forest liming does

Since the early 1980s, more than 3.2 million hectares of forest have been limed in Germany. This was intended to counteract further area-wide soil acidification and loss of soil quality. As the findings of the second forest soil condition survey show, soil protection liming has significant effects on soil condition and ground vegetation.

Fact check

Can CO₂ Certificates for Humus contribute to Climate Protection?

Humus is an important CO₂ store. CO₂ certificates are intended to create an incentive for agriculture to use the potential of humus build-up for climate protection. To be credible, these certificates must meet strict criteria. However, most do not. Learn more in our fact check.