Effect of mesofaunal activity on the rehabilitation of sealed soil surfaces

The impact of soil mesofauna on the rehabilitation of soil surfaces sealed by rainfall was investigated in a long-term laboratory experiment. Fifteen undisturbed soil monoliths from the Ap horizon of a Gleyic Podzoluvisol/Haplic Luvisol derived from loess were obtained after conventional tillage and seedbed preparation. The soil of this site is known to be susceptible to surface sealing as a result of rainfall activity. All monoliths were defaunated in a microwave oven and then inoculated with mesofauna, some with 300 individuals of Collembola and others with 200 individuals of Enchytraeidae. Additional monoliths were left uninoculated for comparison. Ten monoliths were then treated with simulated rainfall (intensity: 29 mm h(-1); time: 60 min) to form a surface seal. The roughness of all 15 monoliths was measured using a non-contact laser scanner immediately and after 6 and 18 months. Differences in the soil surface roughness were assumed to indicate mesofaunal activities and intrinsic soil processes. Soil surface roughness was significantly different between monoliths with and without rain impact, Monoliths subjected to rainfall showed significant differences in soil surface roughness between those with and without mesofauna as well as between monoliths inoculated with Collembola and Enchytraeidae. The roughness differences detected between unsealed monoliths were not significant. Over the entire experimental time of 18 months the relative changes in sealed uninoculated monoliths were much lower than the alterations as a result of mesofaunal activities. The results show that within a few months the activities of Collembola and Enchytraeidae distinctly contribute to the rehabilitation of sealed soil surfaces and the development of a finely structured soil surface microrelief. (C) 2001 Elsevier Science B.V. All rights reserved.