TY - JOUR A1 - Vaidya, Shrijana A1 - Schmidt, Marten A1 - Rakowski, Peter A1 - Bonk, Norbert A1 - Verch, Gernot A1 - Augustin, Jürgen A1 - Sommer, Michael A1 - Hoffmann, Mathias T1 - A novel robotic chamber system allowing to accurately and precisely determining spatio-temporal CO2 flux dynamics of heterogeneous croplands JF - Agricultural and forest meteorology N2 - The precise and accurate assessment of carbon dioxide (CO2) exchange is crucial to identify terrestrial carbon (C) sources and sinks and for evaluating their role within the global C budget. The substantial uncertainty in disentangling the management and soil impact on measured CO2 fluxes are largely ignored especially in cropland. The reasons for this lies in the limitation of the widely used eddy covariance as well as manual and automatic chamber systems, which either account for short-term temporal variability or small-scale spatial heterogeneity, but barely both. To address this issue, we developed a novel robotic chamber system allowing for dozens of spatial measurement repetitions, thus enabling CO2 exchange measurements in a sufficient temporal and high small-scale spatial resolution. The system was tested from 08th July to 09th September 2019 at a heterogeneous field (100 m x 16 m), located within the hummocky ground moraine landscape of northeastern Germany (CarboZALF-D). The field is foreseen for a longer-term block trial manipulation experiment extending over three erosion induced soil types and was covered with spring barley. Measured fluxes of nighttime ecosystem respiration (R-eco) and daytime net ecosystem exchange (NEE) showed distinct temporal patterns influenced by crop phenology, weather conditions and management practices. Similarly, we found clear small-scale spatial differences in cumulated (gap-filled) R-eco, gross primary productivity (GPP) and NEE fluxes affected by the three distinct soil types. Additionally, spatial patterns induced by former management practices and characterized by differences in soil pH and nutrition status (P and K) were also revealed between plots within each of the three soil types, which allowed compensating for prior to the foreseen block trial manipulation experiment. The results underline the great potential of the novel robotic chamber system, which not only detects short-term temporal CO2 flux dynamics but also reflects the impact of small-scale spatial heterogeneity. KW - Automatic chamber KW - Net ecosystem exchange (NEE) KW - Gross primary KW - productivity (GPP) KW - Ecosystem respiration (R-eco) KW - Soil erosion KW - Soil KW - heterogeneity Y1 - 2021 U6 - https://doi.org/10.1016/j.agrformet.2020.108206 SN - 0168-1923 SN - 1873-2240 VL - 296 PB - Elsevier CY - Amsterdam ER - TY - JOUR A1 - Hoffmann, Mathias A1 - Jurisch, Nicole A1 - Alba, Juana Garcia A1 - Borraz, Elisa Albiac A1 - Schmidt, Marten A1 - Huth, Vytas A1 - Rogasik, Helmut A1 - Rieckh, Helene A1 - Verch, Gernot A1 - Sommer, Michael A1 - Augustin, Jürgen T1 - Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks BT - a comparison between automatic chamber-derived C budgets and repeated soil inventories JF - Biogeosciences N2 - Carbon (C) sequestration in soils plays a key role in the global C cycle. It is therefore crucial to adequately monitor dynamics in soil organic carbon (Delta SOC) stocks when aiming to reveal underlying processes and potential drivers. However, small-scale spatial (10-30 m) and temporal changes in SOC stocks, particularly pronounced in arable lands, are hard to assess. The main reasons for this are limitations of the well-established methods. On the one hand, repeated soil inventories, often used in long-term field trials, reveal spatial patterns and trends in Delta SOC but require a longer observation period and a sufficient number of repetitions. On the other hand, eddy covariance measurements of C fluxes towards a complete C budget of the soil-plant-atmosphere system may help to obtain temporal Delta SOC patterns but lack small-scale spatial resolution. To overcome these limitations, this study presents a reliable method to detect both short-term temporal dynamics as well as small-scale spatial differences of Delta SOC using measurements of the net ecosystem carbon balance (NECB) as a proxy. To estimate the NECB, a combination of automatic chamber (AC) measurements of CO2 exchange and empirically modeled aboveground biomass development (NPPshoot / were used. To verify our method, results were compared with Delta SOC observed by soil resampling. Soil resampling and AC measurements were performed from 2010 to 2014 at a colluvial depression located in the hummocky ground moraine landscape of northeastern Germany. The measurement site is characterized by a variable groundwater level (GWL) and pronounced small-scale spatial heterogeneity regarding SOC and nitrogen (Nt) stocks. Tendencies and magnitude of Delta SOC values derived by AC measurements and repeated soil inventories corresponded well. The period of maximum plant growth was identified as being most important for the development of spatial differences in annual Delta SOC. Hence, we were able to confirm that AC-based C budgets are able to reveal small-scale spatial differences and short-term temporal dynamics of Delta SOC. Y1 - 2017 U6 - https://doi.org/10.5194/bg-14-1003-2017 SN - 1726-4170 SN - 1726-4189 VL - 14 IS - 4 SP - 1003 EP - 1019 PB - Copernicus CY - Göttingen ER - TY - GEN A1 - Hoffmann, Mathias A1 - Jurisch, Nicole A1 - Alba, Juana Garcia A1 - Borraz, Elisa Albiac A1 - Schmidt, Marten A1 - Huth, Vytas A1 - Rogasik, Helmut A1 - Rieckh, Helene A1 - Verch, Gernot A1 - Sommer, Michael A1 - Augustin, Jürgen T1 - Detecting small-scale spatial heterogeneity and temporal dynamics of soil organic carbon (SOC) stocks BT - a comparison between automatic chamber-derived C budgets and repeated soil inventories T2 - Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe N2 - Carbon (C) sequestration in soils plays a key role in the global C cycle. It is therefore crucial to adequately monitor dynamics in soil organic carbon (Delta SOC) stocks when aiming to reveal underlying processes and potential drivers. However, small-scale spatial (10-30 m) and temporal changes in SOC stocks, particularly pronounced in arable lands, are hard to assess. The main reasons for this are limitations of the well-established methods. On the one hand, repeated soil inventories, often used in long-term field trials, reveal spatial patterns and trends in Delta SOC but require a longer observation period and a sufficient number of repetitions. On the other hand, eddy covariance measurements of C fluxes towards a complete C budget of the soil-plant-atmosphere system may help to obtain temporal Delta SOC patterns but lack small-scale spatial resolution. To overcome these limitations, this study presents a reliable method to detect both short-term temporal dynamics as well as small-scale spatial differences of Delta SOC using measurements of the net ecosystem carbon balance (NECB) as a proxy. To estimate the NECB, a combination of automatic chamber (AC) measurements of CO2 exchange and empirically modeled aboveground biomass development (NPPshoot / were used. To verify our method, results were compared with Delta SOC observed by soil resampling. Soil resampling and AC measurements were performed from 2010 to 2014 at a colluvial depression located in the hummocky ground moraine landscape of northeastern Germany. The measurement site is characterized by a variable groundwater level (GWL) and pronounced small-scale spatial heterogeneity regarding SOC and nitrogen (Nt) stocks. Tendencies and magnitude of Delta SOC values derived by AC measurements and repeated soil inventories corresponded well. The period of maximum plant growth was identified as being most important for the development of spatial differences in annual Delta SOC. Hence, we were able to confirm that AC-based C budgets are able to reveal small-scale spatial differences and short-term temporal dynamics of Delta SOC. T3 - Zweitveröffentlichungen der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe - 666 KW - net ecosystem exchange KW - North Central region KW - no-till ecosystem KW - eddy covariance KW - CO2 fluxes KW - dioxide exchange KW - United States KW - gas-exchange KW - agricultural landscapes KW - monitoring networks Y1 - 2019 U6 - http://nbn-resolving.de/urn/resolver.pl?urn:nbn:de:kobv:517-opus4-417118 SN - 1866-8372 IS - 666 ER - TY - JOUR A1 - Mueller, Marina Elsa Herta A1 - Koszinski, Sylvia A1 - Brenning, Alexander A1 - Verch, Gernot A1 - Korn, Ulrike A1 - Sommer, Michael T1 - Within-field variation of mycotoxin contamination of winter wheat is related to indicators of soil moisture JF - Plant and soil N2 - Humidity is an important determinant of the mycotoxin production (DON, ZEA) by Fusarium species in the grain ears. From a landscape perspective humidity is not evenly distributed across fields. The topographically-controlled redistribution of water within a single field rather leads to spatially heterogeneous soil water content and air humidity. Therefore we hypothesized that the spatial distribution of mycotoxins is related to these topographically-controlled factors. To test this hypothesis we studied the mycotoxin concentrations at contrasting topographic relief positions, i.e. hilltops and depressions characterized by soils of different soil moisture regimes, on ten winter wheat fields in 2006 and 2007. Maize was the preceding crop and minimum tillage was practiced in the fields. The different topographic positions were associated with moderate differences in DON and ZEA concentrations in 2006, but with significant differences in 2007, with six times higher median ZEA and two times higher median DON detected at depression sites compared to the hilltops. The depression sites correspond to a higher topographic wetness index as well as redoximorphic properties in soil profiles, which empirically supports our hypothesis at least for years showing wetter conditions in sensitive time windows for Fusarium infections. KW - Wheat KW - Mycotoxins KW - Within-field variation KW - Topography KW - Humidity KW - Soil redoximorphic feature Y1 - 2011 U6 - https://doi.org/10.1007/s11104-010-0695-5 SN - 0032-079X SN - 1573-5036 VL - 342 IS - 1-2 SP - 289 EP - 300 PB - Springer CY - Dordrecht ER -