Soil Functions in Earth's Critical Zone : Key Results and Conclusions
Banwart, S.A. ; Bernasconi, S.M. ; Blum, W.E.H. ; Souza, D.M. de; Chabaux, F. ; Duffy, C. ; Kercheva, M. ; Krám, P. ; Lair, G.J. ; Lundin, L. ; Menon, M. ; Nikolaidis, N. ; Novak, M. ; Panagos, P. ; Ragnarsdottir, K.V. ; Robinson, D.A. ; Rousseva, S. ; Ruiter, P. de; Gaans, P. van; Weng, L. ; White, T. ; Zhang, B. - \ 2017
Advances in Agronomy 142 (2017). - ISSN 0065-2113 - p. 1 - 27.
Critical zone - Ecosystem services - Soil - Soil functions - Water
This chapter summarizes the methods, results, and conclusions of a 5-year research project (SoilTrEC: Soil Transformations in European Catchments) on experimentation, process modeling, and computational simulation of soil functions and soil threats across a network of European, Chinese, and United States Critical Zone Observatories (CZOs). The study focused on the soil functions of biomass production, carbon storage, water storage and transmission, water filtration, transformation of nutrients, and maintaining habitat and genetic diversity.The principal results demonstrate that soil functions can be quantified as biophysical flows and transformations of material and energy. The functions can be simulated with mathematical models of soil processes within the soil profile and at the critical zone interfaces with vegetation and atmosphere, surface waters and the below-ground vadose zone and groundwater. A new dynamic model for soil structure development, together with data sets from the CZOs, demonstrate both seasonal fluctuations in soil structure dynamics related to vegetation dynamics and soil carbon inputs, and long-term trends (decadal) in soil carbon storage and soil structure development.Cross-site comparison for 20 soil profiles at seven field sites with variation in soil type, lithology, land cover, land use, and climate demonstrate that sites can be classified, using model parameter values for soil aggregation processes together with climatic conditions and soil physical properties, along a trajectory of soil structure development from incipient soil formation through productive land use to overly intensive land use with soil degradation.A new modeling code, the Integrated Critical Zone model, was applied with parameter sets developed from the CZO site data to simulate the biophysical flows and transformations that quantify multiple soil functions. Process simulations coupled the new model for soil structure dynamics with existing modeling approaches for soil carbon dynamics, nutrient transformations, vegetation dynamics, hydrological flow and transport, and geochemical equilibria and mineral weathering reactions. Successful calibration, testing, and application of the model with data sets from horticulture plot manipulation experiments demonstrate the potential to apply modeling and simulation to the scoping and design of new practices and policy options to enhance soil functions and reduce soil threats worldwide.
Sediment provenance, soil development, and carbon content in fluvial and manmade terraces at Koiliaris River Critical Zone Observatory
Moraetis, Daniel ; Paranychianakis, Nikolaos V. ; Nikolaidis, N.P. ; Banwart, S.A. ; Rousseva, S. ; Kercheva, M. ; Nenov, Martin ; Shishkov, T. ; Ruiter, P.C. de; Bloem, J. ; Blum, W.E.H. ; Lair, G.J. ; Gaans, Pauline van; Verheul, M. - \ 2015
Journal of Soils and Sediments 15 (2015)2. - ISSN 1439-0108 - p. 347 - 364.
The purpose of this study was the investigation of sediment provenance and soil formation processes within a Mediterranean watershed (Koiliaris CZO in Greece) with particular emphasis on natural and manmade terraces. Material and methods Five sites (K1–K5) were excavated and analyzed for their pedology (profile description), geochemistry [including rare earth elements (REEs) and other trace elements], texture, and mineralogy along with chronological analysis (optical luminescence dating). The selected sites have the common characteristic of being flat terraces while the sites differed with regard to bedrock lithology, elevation, and land use. Results and discussion Three characteristic processes of soil genesis were identified: (1) sediments transportation from outcrops of metamorphic rocks and sedimentation at the fluvial sites (K1–K2), (2) in situ soil development in manmade terraces (K3, K4), and (3) strong eolian input and/or material transported by gravity from upslope at the mountainous site (K5). REE patterns verified the soil genesis processes while they revealed also soil development processes such as (a) calcite deposition (K1), (b) clay illuviation and strong weathering (K4), and (c) possibly fast oxidation/precipitation processes (K3). Carbon sequestration throughout the soil profile was high at manmade terraces at higher elevation compared to fluvial environments due to both climatic effects and possibly intensive anthropogenic impact. Conclusions Soils at Koiliaris CZO were rather young soils with limited evolution. The different soil age, land use, and climatic effect induced various soil genesis and soil development processes. The manmade terraces at higher elevation have much higher carbon sequestration compared to the anthropogenic impacted fluvial areas.
Aggregation and organic matter in subarctic Andosols under different grassland management
Lehtinen, T. ; Gisladottir, G. ; Lair, G.J. ; Leeuwen, J.P. van; Blum, W.E.H. ; Bloem, J. ; Steffens, M. ; Ragnarsdottir, K.V. - \ 2015
Acta Agriculturae Scandinavica Section B-Soil and Plant Science 65 (2015)3. - ISSN 0906-4710 - p. 246 - 263.
c-13 nmr-spectroscopy - soil microbial biomass - mediterranean conditions - structural stability - cultivated soils - farming systems - volcanic soils - carbon stocks - land-use - tillage
Quantity and quality of soil organic matter (SOM) affect physical, chemical, and biological soil properties, and are pivotal to productive and healthy grasslands. Thus, we analyzed the distribution of soil aggregates and assessed quality, quantity, and distribution of SOM in two unimproved and improved (two organic and two conventional) grasslands in subarctic Iceland, in Haplic and Histic Andosols. We also evaluated principal physicochemical and biological soil properties, which influence soil aggregation and SOM dynamics. Macroaggregates (>250 µm) in topsoils were most prominent in unimproved (62–77%) and organically (58–69%) managed sites, whereas 20–250 µm aggregates were the most prominent in conventionally managed sites (51–53%). Macroaggregate stability in topsoils, measured as mean weight diameter, was approximately twice as high in organically managed (12–20 mm) compared with the conventionally managed (5–8 mm) sites, possibly due to higher organic inputs (e.g., manure, compost, and cattle urine). In unimproved grasslands and one organic site, macroaggregates contributed between 40% and 70% of soil organic carbon (SOC) and nitrogen to bulk soil, whereas in high SOM concentration sites free particulate organic matter contributed up to 70% of the SOC and nitrogen to bulk soil. Aggregate hierarchy in Haplic Andosols was confirmed by different stabilizing mechanisms of micro- and macroaggregates, however, somewhat diminished by oxides (pyrophosphate-, oxalate-, and dithionite-extractable Fe, Al, and Mn) acting as binding agents for macroaggregates. In Histic Andosols, no aggregate hierarchy was observed. The higher macroaggregate stability in organic farming practice compared with conventional farming is of interest due to the importance of macroaggregates in protecting SOM and soils from erosion, which is a prerequisite for soil functions in grasslands that are envisaged for food production in the future.
|Farming effects on soil organic matter and aggregate stability of Icelandic Brown and Histic Andosols
Lehtinen, T. ; Gisladottir, G. ; Lair, G.J. ; Leeuwen, J. van; Blum, W.E.H. ; Bloem, J. ; Ragnarsdottir, K.V. - \ 2013
In: Proceedings of the Soil Carbon Sequestration for climate, food security and ecosystem services, May 26-29, 2013, Reykjavik, Iceland. - Reykjavik : Soil Conservation Service of Iceland & Agricultural University of Iceland - p. 32 - 32.