Formation, Properties and Distribution of Singular Deep-Ploughed Soils of Central Europe and Recommendations for WRB.
Luise Giani, Institute of Biology and Environmental Science, Carl von Ossietzky Straße, Oldenburg, Germany and Hans-Peter Blume, University of Kiel, Schlieffenallee 28, Schlieffenallee 28, Kiel, 24105, Germany.
In areas with early dense population, like northwest Europe, techniques have been developed to increase the natural soil fertility. As a consequence, many anthropogenic soils can be found, which are formed or profoundly modified through human activities. According to the WRB these soils key out as Anthrosols, having a Hortic, Irragric, Plaggic, Terric or an Anthroquic and Hydragric horizon. The names refer to the kind of land use management or cultivation technique. Although Plaggic Anthrosols are widespread and most known for northwest Europe, another set of anthropogenic soils, which are formed by singular deep-ploughing, are probably even more widespread but less considered. The singular deep-ploughing cultivation technique was introduced nearly hundred years ago. It works as a one-time ploughing to soil depths of 80 to 250 cm. Its application was preconditioned by the invention of the steam plough by John Fowler in 1856. In the beginning, mostly Podzols and then Luvisols were treated by singular deep-ploughing. Since 1936 this method was also introduced to thin peats, mostly to bogs but also to fens, which have been ploughed together with the underlying almost sandy material. Just after World War II, singular deep-ploughing was extended to convert waste sites into productive arable land, simultaneously supplying many refugees. Deep-ploughing is applied until today, but meanwhile seldom. The morphological characteristics of singular deep-ploughed soils are vertical tilted layers of the former top and the former sub soil, which alter continuously. They disappear at the top by regular ploughing but stay in the deeper part as distinctive attributes. By singular deep-ploughing the soil properties were enhanced profoundly, although up to now only few data are available. In respect of hydrology water-retaining horizons are broken off, humus-rich sub soils layers increase the water-holding capacity, sandy ones enhance drainage. Looking at physical properties, it is obvious that rooting hindered horizons became absent, thus enhancing root penetration, and the interconnected pores of various sizes meliorate water and air dynamics. Additionally, the loading capacity is improved. Chemically, an increased CEC is likely because of high contents of organic matter. More investigations in respect of soil properties of different singular deep-ploughed soils and their distribution have to be carried out and will be presented at the 18th WCSS. Apparently the terms Aric Anthrosol and Ari-Anthropic Regosol appear in the literature for singular deep-ploughing soils. As Anthropic refers to a profoundly modified soil by human activity caused by factors other than those related to cultivation and Ari refers to remnants of diagnostic horizons caused by repeated deep-ploughing, the terms do not consider the main characteristics and are not appropriate? With the singular deep-ploughing technique a new anthropogenic soil is formed with special hydrological, physical and chemical properties, which is probably more widespread than Plaggic Anthrosols.Within the German Systematics these soils are called Treposols on the soils type level, when belonging to the group of terrestrial anthropogenic soils deeply modified by men by factors related to cultivation (Cultisols). Consequently, we propose to admit an adequate qualifier to the WRB system. To key out singular deep-ploughing soils we recommend adding Trepic as a qualifier in respect of Anthrosols.