Soil structure on poorly-reclaimed disturbed sites in Bavaria

Abstract

Soil structural properties of two reclaimed sites in southern Upper Bavaria were compared with those of adjacent areas under agricultural use. At one site on loamy moraine, undisturbed soils were classified as Typic Hapludolls, whereas the soils of the reclaimed area were classified as Lithic Rendolls due to the high content of calcareous gravel present in the subsoils. At the other site on loamy alluvium, the soils on reclaimed and undisturbed land were classified as Typic Dystrochrepts. The reclamation operation consisted of deep subsoiling using a bulldozer equipped with a deep-ripper before and/or after refilling the original excavations. At both sites the soils were severely compacted by the reclamation procedure, yielding bulk density values up to 1.84 g/cm 3 in depths >15 cm and 1.67 g/cm 3 in depths >40 cm, as compared to 1.38 and 1.50 g/cm 3 in the unaffected profiles at both sites. This strong compaction reduced the average amount of pores >10 μm from 9.6 to 3.1%v, and interrupted pore continuity, resulting in very poor infiltrability of the reclaimed soils. Recommendations are given for avoiding, as well as for overcoming, the long-lasting effects of soil compaction on soil structure and plant growth.