Soil wetting‐drying and water‐retention properties in a mine‐soil treated with composted and thermally‐dried sludges |
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| Authors: | G Ojeda S Mattana M Bonmatí S K Woche J Bachmann |
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| Institution: | 1. IMAR – Institute of Marine Research, c/o Department of Life Sciences, Faculty of Sciences and Technology, University of Coimbra, 3004‐517 Coimbra, Portugal;2. CREAF (Centre for Ecological Research and Forestry Applications), Department of Animal and Plant Biology and Ecology, Autonomous University of Barcelona, 08193 Bellaterra, Spain;3. Escola Superior d’Agricultura, Universitat Politècnica de Catalunya, 08860 Castelldefels, Barcelona, Spain;4. Institute of Soil Science, Leibniz University of Hannover, Herrenhaeuser Str. 2, 30419 Hannover, Germany |
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| Abstract: | The main objective of this study was to analyse how different sewage sludges influence soil wetting and drying dynamics. Three composted and three thermally‐dried municipal sludges from different wastewater plants located in Catalonia (NE Spain) were mixed with a mine‐soil obtained from a limestone quarry. Measurements of the time required to reach zero contact angle ( ) and water holding time (WHT) provided information on the time required for a mine‐soil to reach its complete wettability and the residence time of water stored between ?0.75 and ?25 MPa of soil suction, respectively. One month after sludge amendments, one composted and one thermally‐dried sludge significantly increased  . WHT was increased in the mine‐soil treated by composted sludges (50.6% by Blanes' sludge, 65.5% by Manresa's sludge and 52.5% by Vilaseca's sludge) one month after sludge amendments. The amount of water retained in the mine‐soil was increased by all composted sludges and one thermally‐dried sludge after one month (by 42.3% with Blanes' sludge, 42.3% with Manresa's sludge, 65.7% with Vilaseca's sludge and 23.9% with Mataró's sludge) and one year after sludge amendments and at a small suction. Increments in WHT corresponded with the amount of water retained so the time‐scale of soil water availability should also be considered. The  value was modified mainly by increments in carbon stock and microbial biomass, while the WHT was modified mainly by increments in pH and electrical conductivity. Under similar air‐drying conditions, mine‐soil treated with composted sludges retained more water for longer compared with thermally‐dried sludges. |
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