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Whereas many researchers still approach Terra Preta (TP) as a soil category, new evidence suggests that TP refers to a directional grading of soil property changes (i.e., color, pH, nutrients, etc.) within human-made soils, originating from human activities in pre-Columbian times. Currently, most TP research focuses on the Brazilian part of the Amazon basin, but only little information is available on TP soils in the Colombian Amazon. Here, we sampled four TP and surrounding soils in the Colombian Amazon region at different soil depths and analyzed them for (i) general soil properties such as color, pH and texture, (ii) soil organic carbon and black carbon (BC) contents, the latter using benzene polycarboxylic acids as molecular marker, (iii) phosphorus availability based on sequential fractionation, and (iv) microbial residue contents using amino sugars. Our data from Colombia’s middle Caquetá River and Leticia confirmed that SOC, BC, and total P were present in significantly higher concentrations in the TP areas than the surrounding soils, while pH values and microbial residue contents were unchanged. The enrichment of P forms comprised both easily extractable and stable P pools, which both dominated to a different degree, both in TP and adjacent soils. The different degree of SOC, BC and P enrichment suggests different amounts of waste disposal by the ancient populations at different TP sites, now warranting further research for reconstructing ancient population sizes from TP chemical analyses.
Juan Orozco-Ortiz; Clara Peña-Venegas; Sara Bauke; Christian Borgemeister; Ramona Mörchen; Eva Lehndorff; Wulf Amelung. Terra Preta Properties in Northwestern Amazonia (Colombia). Sustainability 2021, 13, 7088 .
AMA StyleJuan Orozco-Ortiz, Clara Peña-Venegas, Sara Bauke, Christian Borgemeister, Ramona Mörchen, Eva Lehndorff, Wulf Amelung. Terra Preta Properties in Northwestern Amazonia (Colombia). Sustainability. 2021; 13 (13):7088.
Chicago/Turabian StyleJuan Orozco-Ortiz; Clara Peña-Venegas; Sara Bauke; Christian Borgemeister; Ramona Mörchen; Eva Lehndorff; Wulf Amelung. 2021. "Terra Preta Properties in Northwestern Amazonia (Colombia)." Sustainability 13, no. 13: 7088.
Bioturbation involves the incorporation of residues from the surface soil into the subsoil; however, common small soil ‘bioengineers’, such as earthworms or termites, are unlikely to transport human artifacts to deeper soil horizons. However, such artifacts occur in the deeper soil horizons within Amazonian Anthrosols (Terra Preta). Here we test the assumption that such tasks could be carried out by fly larvae, which could thus play a crucial role in waste decomposition and associated soil mixing under tropical conditions. We performed two greenhouse experiments with sandy substrate covered with layers of organic waste, ceramic fragments, and black soldier fly larvae (BSFL) (Hermetia illucens (L.) (Dipt.: Stratiomyidae)). We used in-situ images to assess the rate of bioturbation by BSFL, and then designed our main study to observe waste dissipation (reduction of organic carbon and phosphorus contents from waste model trials with and without charcoal) as related to larval-induced changes in soil properties. We found that the bioturbation of macroinvertebrates like BSFL was able to bury even large (> 5 cm) ceramic fragments within hours, which coincided with high soil growth rates (0.5 cm h-1). The sandy soil was subsequently heavily enriched with organic matter and phosphorus originating from organic waste. We conclude that BSFL, and possibly other fly species, are important, previously overlooked soil ‘bioengineers’, which may even contribute to the burial of artifacts in Anthrosols and other terrestrial waste dumps.
Juan M. Orozco-Ortiz; Sara L. Bauke; Christian Borgemeister; Eva Lehndorff; Wulf Amelung. Bioturbation by black soldier fly larvae—Rapid soil formation with burial of ceramic artifacts. PLOS ONE 2021, 16, e0252032 .
AMA StyleJuan M. Orozco-Ortiz, Sara L. Bauke, Christian Borgemeister, Eva Lehndorff, Wulf Amelung. Bioturbation by black soldier fly larvae—Rapid soil formation with burial of ceramic artifacts. PLOS ONE. 2021; 16 (6):e0252032.
Chicago/Turabian StyleJuan M. Orozco-Ortiz; Sara L. Bauke; Christian Borgemeister; Eva Lehndorff; Wulf Amelung. 2021. "Bioturbation by black soldier fly larvae—Rapid soil formation with burial of ceramic artifacts." PLOS ONE 16, no. 6: e0252032.
Understanding P uptake in soil‐plant systems requires suitable P tracers. The stable oxygen isotope ratio in phosphate (expressed as δ18OP) is an alternative to radioactive labeling, but the degree to which plants preserve the δ18OP value of the P source is unclear. We hypothesized that the source signal will be preserved in roots rather than shoots. In soil and hydroponic experiments with spring wheat (Triticum aestivum L.), we replaced irrigation water by 18O‐labeled water for up to 10 days. We extracted plant inorganic phosphates with trichloroacetic acid (TCA), assessed temporal dynamics of δ18OTCA‐P values after changing to 18O‐labeled water and combined the results with a mathematical model. Within one week, full equilibration of δ18OTCA‐P values with the isotope value of the water in the growth medium occurred in shoots but not in roots. Model results further indicated that root δ18OTCA‐P values were affected by back‐transport of phosphate from shoots to roots, with a greater contribution of source P at higher temperatures when back‐transport was reduced. Root δ18OTCA‐P partially preserved the source signal, providing an indicator of P uptake sources. This now needs to be tested extensively for different species, soil and climate conditions to enable application in future ecosystem studies.
Sara L. Bauke; Andrea Schnepf; Christian von Sperber; Natalie Orlowski; Hans Lewandowski; Tobias Selzner; Federica Tamburini; Wulf Amelung. Tracing uptake and translocation of phosphorus in wheat using oxygen isotopes and mathematical modelling. New Phytologist 2021, 230, 1883 -1895.
AMA StyleSara L. Bauke, Andrea Schnepf, Christian von Sperber, Natalie Orlowski, Hans Lewandowski, Tobias Selzner, Federica Tamburini, Wulf Amelung. Tracing uptake and translocation of phosphorus in wheat using oxygen isotopes and mathematical modelling. New Phytologist. 2021; 230 (5):1883-1895.
Chicago/Turabian StyleSara L. Bauke; Andrea Schnepf; Christian von Sperber; Natalie Orlowski; Hans Lewandowski; Tobias Selzner; Federica Tamburini; Wulf Amelung. 2021. "Tracing uptake and translocation of phosphorus in wheat using oxygen isotopes and mathematical modelling." New Phytologist 230, no. 5: 1883-1895.
Phosphorus (P) tracing in natural environments is challenging, lacking stable P isotopes Oxygen isotope ratios in phosphate (δ18OP) represent a novel tool for tracing the biological cycling of P from the global scale down to hotspots at the micro‐scale and within particular soil compartments such as aggregates or pores. Despite the small number of studies available so far, existing data indicate that δ18OP values point to where, at what extent and how efficiently P is recycled in soils.
Sara L. Bauke. Perspectives from the Fritz‐Scheffer Awardee 2019. Oxygen isotopes in phosphate—The key to phosphorus tracing? Journal of Plant Nutrition and Soil Science 2020, 184, 12 -19.
AMA StyleSara L. Bauke. Perspectives from the Fritz‐Scheffer Awardee 2019. Oxygen isotopes in phosphate—The key to phosphorus tracing? Journal of Plant Nutrition and Soil Science. 2020; 184 (1):12-19.
Chicago/Turabian StyleSara L. Bauke. 2020. "Perspectives from the Fritz‐Scheffer Awardee 2019. Oxygen isotopes in phosphate—The key to phosphorus tracing?" Journal of Plant Nutrition and Soil Science 184, no. 1: 12-19.
Tree roots penetrate the soil to several meters depth, but the role of subsoils for the supply of nutrient elements such as phosphorus (P) to the trees is poorly understood. Here, we tested the hypothesis that increased P deficiency in the topsoil results in an increased microbial recycling of P from the forest subsoil. We sampled soils from four German temperate forest sites representing a gradient in total P stocks. We analyzed the oxygen isotopic composition of HCl-extractable phosphate (δ18OP) and identified differences in P speciation with increasing soil depth using X-ray absorption near-edge structure (XANES) spectroscopy. We further determined microbial oxygen demand with and without nutrient supply at different soil depths to analyse nutrient limitation of microbial growth and used nanoscale secondary ion mass spectrometry (NanoSIMS) to visualize spatial P gradients in the rhizosphere. We found that δ18OPvalues in the topsoil of all sites were close to the isotopic signal imparted by biological cycling when oxygen isotopes in phosphate are exchanged by enzymatic activity. However, with increasing soil depth and increasing HCl-P concentrations, δ18Ο values continuously decreased towards values expected for primary minerals in parent material at depths below 60 cm at sites with high subsoil P stocks and below more than 2 m at sites with low subsoil P stocks, respectively. For these depths, XANES spectra also indicated the presence of apatite. NanoSIMS images showed an enrichment of P in the rhizosphere in the topsoil of a site with high P stocks, while this P enrichment was absent at a site with low P stocks and in both subsoils. Addition of C, N and P alone or in combination revealed that microbial activity in subsoils of sites with low P stocks was mostly P limited, whereas sites with high P stocks indicated N limitation or N and P co-limitation. We conclude that subsoil P resources are recycled by trees and soil microorganisms. With continued weathering of the bedrock and mobilisation of P from the weathered rocks, P cycling will proceed to greater depths, especially at sites characterised by P limitation.
Andrei Rodionov; Sara L. Bauke; Christian Von Sperber; Carmen Hoeschen; Ellen Kandeler; Jens Kruse; Hans Lewandowski; Sven Marhan; Carsten W. Mueller; Margaux Simon; Federica Tamburini; David Uhlig; Friedhelm Von Blanckenburg; Friederike Lang; Wulf Amelung. Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems. Biogeochemistry 2020, 150, 1 -16.
AMA StyleAndrei Rodionov, Sara L. Bauke, Christian Von Sperber, Carmen Hoeschen, Ellen Kandeler, Jens Kruse, Hans Lewandowski, Sven Marhan, Carsten W. Mueller, Margaux Simon, Federica Tamburini, David Uhlig, Friedhelm Von Blanckenburg, Friederike Lang, Wulf Amelung. Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems. Biogeochemistry. 2020; 150 (3):1-16.
Chicago/Turabian StyleAndrei Rodionov; Sara L. Bauke; Christian Von Sperber; Carmen Hoeschen; Ellen Kandeler; Jens Kruse; Hans Lewandowski; Sven Marhan; Carsten W. Mueller; Margaux Simon; Federica Tamburini; David Uhlig; Friedhelm Von Blanckenburg; Friederike Lang; Wulf Amelung. 2020. "Biogeochemical cycling of phosphorus in subsoils of temperate forest ecosystems." Biogeochemistry 150, no. 3: 1-16.
Sustainable arable cropping relies on repeated liming. Yet, the associated increase in soil pH can reduce the availability of iron (Fe) to plants. We hypothesized that repeated liming, but not pedogenic processes such as lessivage (i.e., translocation of clay particles), alters the Fe cycle in Luvisol soil, therewith affecting Fe isotope composition in soils and crops. Hence, we analyzed Fe concentrations and isotope compositions in soil profiles and winter rye from the long‐term agricultural experimental site in Berlin‐Dahlem, Germany, where a controlled liming trial with three field replicates per treatment has been conducted on Albic Luvisols since 1923. Heterogeneity in subsoil was observed at this site for Fe concentration but not for Fe isotope composition. Lessivage had not affected Fe isotope composition in the soil profiles. The results also showed that almost 100 years of liming lowered the concentration of the HCl‐extractable Fe that was potentially available for plant uptake in the surface soil (0–15 cm) from 1.03 (SE 0.03) to 0.94 (SE 0.01) g kg−1. This HCl‐extractable Fe pool contained isotopically lighter Fe (δ56Fe = −0.05 to −0.29‰) than the bulk soil (δ56Fe = −0.08 to 0.08‰). However, its Fe isotope composition was not altered by the long‐term lime application. Liming resulted in relatively lower Fe concentrations in the roots of winter rye. In addition, liming led to a heavier Fe isotope composition of the whole plants compared with those grown in the non‐limed plots (δ56FeWholePlant_ + Lime = −0.12‰ SE 0.03 vs. δ56FeWholePlant_‐Lime = −0.21‰ SE 0.01). This suggests that the elevated soil pH (increased by 1 unit due to liming) promoted the Fe uptake strategy through complexation of Fe(III) from the rhizosphere, which favoured heavier Fe isotopes. Overall, the present study showed that liming and related increase in pH did not affect the Fe isotope compositions of the soil, but may influence the Fe isotope composition of plants grown in the soil if they alter their Fe uptake strategy upon the change of Fe availability. This article is protected by copyright. All rights reserved.
Bei Wu; Yi Wang; Anne E. Berns; Kathlin Schweitzer; Sara L. Bauke; Roland Bol; Wulf Amelung. Iron isotope fractionation in soil and graminaceous crops after 100 years of liming in the long‐term agricultural experimental site at Berlin‐Dahlem, Germany. European Journal of Soil Science 2020, 72, 289 -299.
AMA StyleBei Wu, Yi Wang, Anne E. Berns, Kathlin Schweitzer, Sara L. Bauke, Roland Bol, Wulf Amelung. Iron isotope fractionation in soil and graminaceous crops after 100 years of liming in the long‐term agricultural experimental site at Berlin‐Dahlem, Germany. European Journal of Soil Science. 2020; 72 (1):289-299.
Chicago/Turabian StyleBei Wu; Yi Wang; Anne E. Berns; Kathlin Schweitzer; Sara L. Bauke; Roland Bol; Wulf Amelung. 2020. "Iron isotope fractionation in soil and graminaceous crops after 100 years of liming in the long‐term agricultural experimental site at Berlin‐Dahlem, Germany." European Journal of Soil Science 72, no. 1: 289-299.
Water and nutrients in the subsoil are valuable resources in crop production but the availability varies with weather conditions and management, in particular the crop rotation. Moreover, constraints such as mechanical resistance or water stress may impede root growth into deeper soil layers. This study presents a simulation-based stochastic approach to investigate the impact of precrops on spring wheat growth and water and nutrient uptake under varying weather conditions. The effect of the three precrops lucerne, chicory and tall fescue on spring wheat growth was investigated extensively in a field trial. For model calibration and evaluation, we selected a year with a dry spell (2010) and one with abundant precipitation (2012) and used field data on biopore densities in the subsoil, crop development, leaf area index, shoot biomass, grain and straw yield, nitrogen (N) and phosphorus in shoot, grain and straw, root length densities, as well as soil moisture and soil N and P concentrations for several soil depths. The modeling framework consisted of the modeling platform SIMPLACE and the stochastic weather generator LARS-WG to consider climate variability. The weather generator was used to generate a synthetic time-series of daily weather data (100 years) based on observed weather data of the experimental site in order to simulate 100 spring wheat growth periods under recent climate conditions for each precrop. Moreover, a 100 year long time-series with annual dry spells in June was generated to analyze the effect of drought during flowering on crop water and nutrient uptake. During the scenario runs, the model was annually reinitialized at sowing to provide identical initial conditions. The experimental data over two years showed that spring wheat growth as well as total N and P uptake were clearly enhanced after precrop lucerne. This was comfirmed by the simulations over 100 years. The simulation runs also prompt that precrop fescue led to higher spring wheat biomass and enhanced subsoil and total water and N uptake in years with normal precipitation pattern compared to precrop chicory, but in drier years, it was vice versa. Because plants compensate for moderate nutrient or water deficiencies, small differences in grain yield may hide significant differences in total and in subsoil N and P uptake.
S.J. Seidel; T. Gaiser; T. Kautz; S.L. Bauke; W. Amelung; K. Barfus; F. Ewert; M. Athmann. Estimation of the impact of precrops and climate variability on soil depth-differentiated spring wheat growth and water, nitrogen and phosphorus uptake. Soil and Tillage Research 2019, 195, 104427 .
AMA StyleS.J. Seidel, T. Gaiser, T. Kautz, S.L. Bauke, W. Amelung, K. Barfus, F. Ewert, M. Athmann. Estimation of the impact of precrops and climate variability on soil depth-differentiated spring wheat growth and water, nitrogen and phosphorus uptake. Soil and Tillage Research. 2019; 195 ():104427.
Chicago/Turabian StyleS.J. Seidel; T. Gaiser; T. Kautz; S.L. Bauke; W. Amelung; K. Barfus; F. Ewert; M. Athmann. 2019. "Estimation of the impact of precrops and climate variability on soil depth-differentiated spring wheat growth and water, nitrogen and phosphorus uptake." Soil and Tillage Research 195, no. : 104427.
Electromagnetic induction (EMI) data are often used to investigate spatial and temporal patterns of soil texture, soil water content and soil salinity. We hypothesized that the EMI methodology might thus also offer potential to detect agricultural legacy effects originating from fertilizer application and irrigation of different fields. Therefore, we performed EMI measurements on two long‐term field experiments (LTFE) at Thyrow near Berlin (Germany) that differed in agricultural management with regard to long‐term irrigation in combination with mineral (NPK and lime) and organic amendments (straw and farmyard manure). Two different rigid‐boom multi‐coil EMI instruments were used to measure simultaneously the apparent electrical conductivity (ECa) over nine different depth ranges to study the entire soil profile from topsoil to deep subsoil. Additionally, soil samples were taken from the different treatments to ground‐truth the measurements and disentangle the nutrient application or irrigation effects from natural soil heterogeneity. The soil samples indicated a rather homogenous soil and the correlation between soil parameters or states were not significant. However, the treatments showed significant differences in measured ECa values. In general, ECa values were largest on regularly irrigated as well as on mineral and organic fertilized plots, with regular irrigation exhibiting the largest impact on EMI records even though the last application was months before the EMI measurement. Overall, this study reveals that EMI data can support the classical in situ assessment of agricultural management effects within LTFE, while offering new potentials in detecting and understanding legacy effects of agricultural management on spatial soil properties at farm level.
Manuela S. Kaufmann; Christian Von Hebel; Lutz Weihermüller; Michael Baumecker; Thomas Döring; Kathlin Schweitzer; Eleanor Hobley; Sara Louise Bauke; Wulf Amelung; Harry Vereecken; Jan Van Der Kruk. Effect of fertilizers and irrigation on multi‐configuration electromagnetic induction measurements. Soil Use and Management 2019, 36, 104 -116.
AMA StyleManuela S. Kaufmann, Christian Von Hebel, Lutz Weihermüller, Michael Baumecker, Thomas Döring, Kathlin Schweitzer, Eleanor Hobley, Sara Louise Bauke, Wulf Amelung, Harry Vereecken, Jan Van Der Kruk. Effect of fertilizers and irrigation on multi‐configuration electromagnetic induction measurements. Soil Use and Management. 2019; 36 (1):104-116.
Chicago/Turabian StyleManuela S. Kaufmann; Christian Von Hebel; Lutz Weihermüller; Michael Baumecker; Thomas Döring; Kathlin Schweitzer; Eleanor Hobley; Sara Louise Bauke; Wulf Amelung; Harry Vereecken; Jan Van Der Kruk. 2019. "Effect of fertilizers and irrigation on multi‐configuration electromagnetic induction measurements." Soil Use and Management 36, no. 1: 104-116.
Subsoil organic carbon (OC) is generally lower in content and more heterogeneous than topsoil OC, rendering it difficult to detect significant differences in subsoil OC storage. We tested the application of laboratory hyperspectral imaging with a variety of machine learning approaches to predict OC distribution in undisturbed soil cores. Using a bias-corrected random forest we were able to reproduce the OC distribution in the soil cores with very good to excellent model goodness-of-fit, enabling us to map the spatial distribution of OC in the soil cores at very high resolution (~53 × 53 µm). Despite a large increase in variance and reduction in OC content with increasing depth, the high resolution of the images enabled statistically powerful analysis in spatial distribution of OC in the soil cores. In contrast to the relatively homogeneous distribution of OC in the plough horizon, the subsoil was characterized by distinct regions of OC enrichment and depletion, including biopores which contained ~2–10 times higher SOC contents than the soil matrix in close proximity. Laboratory hyperspectral imaging enables powerful, fine-scale investigations of the vertical distribution of soil OC as well as hotspots of OC storage in undisturbed samples, overcoming limitations of traditional soil sampling campaigns.
Eleanor Hobley; Markus Steffens; Sara L. Bauke; Ingrid Kögel-Knabner. Hotspots of soil organic carbon storage revealed by laboratory hyperspectral imaging. Scientific Reports 2018, 8, 1 -13.
AMA StyleEleanor Hobley, Markus Steffens, Sara L. Bauke, Ingrid Kögel-Knabner. Hotspots of soil organic carbon storage revealed by laboratory hyperspectral imaging. Scientific Reports. 2018; 8 (1):1-13.
Chicago/Turabian StyleEleanor Hobley; Markus Steffens; Sara L. Bauke; Ingrid Kögel-Knabner. 2018. "Hotspots of soil organic carbon storage revealed by laboratory hyperspectral imaging." Scientific Reports 8, no. 1: 1-13.
Nina Siebers; Sara Louise Bauke; Federica Tamburini; Wulf Amelung. Short-term impacts of forest clear-cut on P accessibility in soil microaggregates: An oxygen isotope study. Geoderma 2018, 315, 59 -64.
AMA StyleNina Siebers, Sara Louise Bauke, Federica Tamburini, Wulf Amelung. Short-term impacts of forest clear-cut on P accessibility in soil microaggregates: An oxygen isotope study. Geoderma. 2018; 315 ():59-64.
Chicago/Turabian StyleNina Siebers; Sara Louise Bauke; Federica Tamburini; Wulf Amelung. 2018. "Short-term impacts of forest clear-cut on P accessibility in soil microaggregates: An oxygen isotope study." Geoderma 315, no. : 59-64.
The main difficulty in the use of 3D root architecture models is correct parameterization. We evaluated distributions of the root traits inter-branch distance, branching angle and axial root trajectories from contrasting experimental systems to improve model parameterization. We analyzed 2D root images of different wheat varieties (Triticum aestivum) from three different sources using automatic root tracking. Model input parameters and common parameter patterns were identified from extracted root system coordinates. Simulation studies were used to (1) link observed axial root trajectories with model input parameters (2) evaluate errors due to the 2D (versus 3D) nature of image sources and (3) investigate the effect of model parameter distributions on root foraging performance. Distributions of inter-branch distances were approximated with lognormal functions. Branching angles showed mean values <90°. Gravitropism and tortuosity parameters were quantified in relation to downwards reorientation and segment angles of root axes. Root system projection in 2D increased the variance of branching angles. Root foraging performance was very sensitive to parameter distribution and variance. 2D image analysis can systematically and efficiently analyze root system architectures and parameterize 3D root architecture models. Effects of root system projection (2D from 3D) and deflection (at rhizotron face) on size and distribution of particular parameters are potentially significant.
Magdalena Landl; Andrea Schnepf; Jan Vanderborght; Glyn Bengough; Sara Louise Bauke; Guillaume Lobet; Roland Bol; Harry Vereecken. Measuring root system traits of wheat in 2D images to parameterize 3D root architecture models. Plant and Soil 2018, 425, 457 -477.
AMA StyleMagdalena Landl, Andrea Schnepf, Jan Vanderborght, Glyn Bengough, Sara Louise Bauke, Guillaume Lobet, Roland Bol, Harry Vereecken. Measuring root system traits of wheat in 2D images to parameterize 3D root architecture models. Plant and Soil. 2018; 425 (1-2):457-477.
Chicago/Turabian StyleMagdalena Landl; Andrea Schnepf; Jan Vanderborght; Glyn Bengough; Sara Louise Bauke; Guillaume Lobet; Roland Bol; Harry Vereecken. 2018. "Measuring root system traits of wheat in 2D images to parameterize 3D root architecture models." Plant and Soil 425, no. 1-2: 457-477.
Arable subsoils store large amounts of phosphorus (P); however, it is unclear to what extent, and under which conditions, subsoil resources might supplement crop P acquisition. Here, we hypothesized that (i) insufficient supply of P in topsoil promotes P acquisition from subsoil and (ii) subsoil P cycling is regulated by nitrogen (N) supply. We sampled two German long-term fertilizer trials in Thyrow (sandy soil) and Gießen (loamy-clayey soil) to 100-cm depth. Treatments received either NPK, NK or PK fertilizer for > 60 years. We assessed soil inorganic (Pi) and organic (Po) P pools following Hedley sequential extraction, and the oxygen isotopic composition of HCl-extractable phosphate (δ18OHCl-P), which differentiates P from primary and secondary (previously biologically cycled) minerals. We found that in the Hedley sequential extraction subsoil resin-P stocks (30–100 cm) in NK plots were 60% (Thyrow) and 8% (Gießen) less than those in NPK plots. Subsoil HCl Pi stocks in NK exceeded those of NPK plots by 70% in Thyrow, but not in Gießen. The NK treatments showed significantly smaller subsoil δ18OHCl-P values than NPK treatments, indicating a predominance of primary (not biologically cycled) minerals and refuting our hypothesis that P deficiency promotes P acquisition from primary minerals. Under N-limiting conditions, subsoil resin-P stocks exceeded those under NPK fertilizer by 117% (Thyrow) and 22% (Gießen), supporting our second hypothesis. We conclude that an efficient use of subsoil P resources is achieved only when nutrient supply in arable topsoils is sufficient.
S. L. Bauke; C. von Sperber; Federica Tamburini; M. I. Gocke; B. Honermeier; K. Schweitzer; M. Baumecker; A. Don; A. Sandhage‐Hofmann; W. Amelung. Subsoil phosphorus is affected by fertilization regime in long‐term agricultural experimental trials. European Journal of Soil Science 2018, 69, 103 -112.
AMA StyleS. L. Bauke, C. von Sperber, Federica Tamburini, M. I. Gocke, B. Honermeier, K. Schweitzer, M. Baumecker, A. Don, A. Sandhage‐Hofmann, W. Amelung. Subsoil phosphorus is affected by fertilization regime in long‐term agricultural experimental trials. European Journal of Soil Science. 2018; 69 (1):103-112.
Chicago/Turabian StyleS. L. Bauke; C. von Sperber; Federica Tamburini; M. I. Gocke; B. Honermeier; K. Schweitzer; M. Baumecker; A. Don; A. Sandhage‐Hofmann; W. Amelung. 2018. "Subsoil phosphorus is affected by fertilization regime in long‐term agricultural experimental trials." European Journal of Soil Science 69, no. 1: 103-112.
Duyen T.T. Hoang; Sara L. Bauke; Yakov Kuzyakov; Johanna Pausch. Rolling in the deep: Priming effects in earthworm biopores in topsoil and subsoil. Soil Biology and Biochemistry 2017, 114, 59 -71.
AMA StyleDuyen T.T. Hoang, Sara L. Bauke, Yakov Kuzyakov, Johanna Pausch. Rolling in the deep: Priming effects in earthworm biopores in topsoil and subsoil. Soil Biology and Biochemistry. 2017; 114 ():59-71.
Chicago/Turabian StyleDuyen T.T. Hoang; Sara L. Bauke; Yakov Kuzyakov; Johanna Pausch. 2017. "Rolling in the deep: Priming effects in earthworm biopores in topsoil and subsoil." Soil Biology and Biochemistry 114, no. : 59-71.
Miriam Athmann; Timo Kautz; Callum Banfield; Sara Louise Bauke; Duyen T.T. Hoang; Marcel Lüsebrink; Johanna Pausch; Wulf Amelung; Yakov Kuzyakov; Ulrich Köpke. Six months of L. terrestris L. activity in root-formed biopores increases nutrient availability, microbial biomass and enzyme activity. Applied Soil Ecology 2017, 120, 135 -142.
AMA StyleMiriam Athmann, Timo Kautz, Callum Banfield, Sara Louise Bauke, Duyen T.T. Hoang, Marcel Lüsebrink, Johanna Pausch, Wulf Amelung, Yakov Kuzyakov, Ulrich Köpke. Six months of L. terrestris L. activity in root-formed biopores increases nutrient availability, microbial biomass and enzyme activity. Applied Soil Ecology. 2017; 120 ():135-142.
Chicago/Turabian StyleMiriam Athmann; Timo Kautz; Callum Banfield; Sara Louise Bauke; Duyen T.T. Hoang; Marcel Lüsebrink; Johanna Pausch; Wulf Amelung; Yakov Kuzyakov; Ulrich Köpke. 2017. "Six months of L. terrestris L. activity in root-formed biopores increases nutrient availability, microbial biomass and enzyme activity." Applied Soil Ecology 120, no. : 135-142.
Biopores are characterised by high concentrations of plant available nutrients and provide preferential pathways for root growth into the subsoil, thereby potentially enabling plants to access phosphorus (P) resources located in the subsoil. Here, we sampled biopores from a replicated agricultural field trial in Klein-Altendorf, Germany, to analyse their nutrient composition and P speciation as determined by Hedley sequential extraction and X-ray absorption near edge structure (XANES) spectroscopy. In addition, we analysed the oxygen isotopic composition of HCl P (δ18OHCl P) as an indicator of long-term effects of biological P turnover. We found that biopore effects were most pronounced in the subsoil, where the concentration of easily extractable (labile) P tended to be greater in biopores than in bulk soil, as evident in both Hedley sequential extraction and XANES spectroscopy. We assume that these findings result from inputs of organic matter from the topsoil as well as an input of Ca-particles into subsoil biopores by earthworm activity. Biologically cycled P was subsequently precipitated as Ca-P as evident by δ18OHCl P values close to equilibrium in biopores even at great depths. When incubating bulk soil samples with 18O-labelled water, however, we observed a significant increase of δ18OHCl P values in the topsoil, but only small if any changes of δ18OHCl P values in the subsoil. Thus, biopores present hotspots of P cycling in the subsoil, but the effect of biopores on overall P turnover in the bulk subsoil is limited
S.L. Bauke; C. von Sperber; Nina Siebers; Federica Tamburini; W. Amelung. Biopore effects on phosphorus biogeochemistry in subsoils. Soil Biology and Biochemistry 2017, 111, 157 -165.
AMA StyleS.L. Bauke, C. von Sperber, Nina Siebers, Federica Tamburini, W. Amelung. Biopore effects on phosphorus biogeochemistry in subsoils. Soil Biology and Biochemistry. 2017; 111 ():157-165.
Chicago/Turabian StyleS.L. Bauke; C. von Sperber; Nina Siebers; Federica Tamburini; W. Amelung. 2017. "Biopore effects on phosphorus biogeochemistry in subsoils." Soil Biology and Biochemistry 111, no. : 157-165.
Phosphorus (P) species in colloidal and dissolved soil fractions may have different distributions. To understand which P species are potentially involved, we obtained water extracts from the surface soils of a gradient from Cambisol, Stagnic Cambisol to Stagnosol from temperate grassland in Germany. These were filtered to < 450 nm, and divided into three procedurally defined fractions: small-sized colloids (20–450 nm), nano-sized colloids (1–20 nm), and dissolved P (< 1 nm), using asymmetric flow field-flow fractionation (AF4), as well as filtration for solution 31P-nuclear magnetic resonance (NMR) spectroscopy. The total P of soil water extracts increased in the order Cambisol < Stagnic Cambisol < Stagnosol due to increasing contributions from the dissolved P fraction. Associations of C–Fe/Al–PO43−/pyrophosphate were absent in nano-sized (1–20 nm) colloids from the Cambisol but not in the Stagnosol. The 31P-NMR results indicated that this was accompanied by elevated portions of organic P in the order Cambisol > Stagnic Cambisol > Stagnosol. Across all soil types, elevated proportions of inositol hexakisphosphate (IHP) species (e.g., myo-, scyllo- and D-chiro-IHP) were associated with soil mineral particles (i.e., bulk soil and small-sized soil colloids), whereas other orthophosphate monoesters and phosphonates were found in the dissolved P fraction. We conclude that P species composition varies among colloidal and dissolved soil fractions after characterization using advanced techniques, i.e., AF4 and NMR. Furthermore, stagnic properties affect P speciation and availability by potentially releasing dissolved inorganic and ester-bound P forms as well as nano-sized organic matter–Fe/Al–P colloids.
Xiaoqian Jiang; Roland Bol; Barbara J. Cade-Menun; Volker Nischwitz; Sabine Willbold; Sara L. Bauke; Harry Vereecken; Wulf Amelung; Erwin Klumpp. Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol. Biogeosciences 2017, 14, 1153 -1164.
AMA StyleXiaoqian Jiang, Roland Bol, Barbara J. Cade-Menun, Volker Nischwitz, Sabine Willbold, Sara L. Bauke, Harry Vereecken, Wulf Amelung, Erwin Klumpp. Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol. Biogeosciences. 2017; 14 (5):1153-1164.
Chicago/Turabian StyleXiaoqian Jiang; Roland Bol; Barbara J. Cade-Menun; Volker Nischwitz; Sabine Willbold; Sara L. Bauke; Harry Vereecken; Wulf Amelung; Erwin Klumpp. 2017. "Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol." Biogeosciences 14, no. 5: 1153-1164.
Macropores may be preferential root pathways into the subsoil. We hypothesised that the presence of macropores promotes P-uptake from subsoil, particularly at limited water supply in surface soil. We tested this hypothesis in a rhizotron experiment with spring wheat (Triticum aestivum cv. Scirocco) under variation of fertilisation and irrigation. Rhizotrons were filled with compacted subsoil (bulk density 1.4 g cm−3), underneath a P-depleted topsoil. In half of these rhizotrons the subsoil contained artificial macropores. Spring wheat was grown for 41 days with and without irrigation and 31P–addition. Also, a 33P–tracer was added at the soil surface to trace P-distribution in plants using liquid scintillation counting and radioactive imaging. Fertilisation and irrigation promoted biomass production and plant P-uptake. Improved growing conditions resulted in a higher proportion of subsoil roots, indicating that the topsoil root system additionally promoted subsoil nutrient acquisition. The presence of macropores did not improve plant growth but tended to increase translocation of 33P into both above- and belowground biomass. 33P–imaging confirmed that this plant-internal transport of topsoil-P extended into subsoil roots. The lack of penetration resistance in macropores did not increase plant growth and nutrient uptake from subsoil here; however, wheat specifically re-allocated topsoil-P for subsoil root growth.
Sara Louise Bauke; K. A. Nagel; Nina Siebers; Andrea Schnepf; W. Amelung; M. Koch; Magdalena Landl; D. Hofmann. Macropore effects on phosphorus acquisition by wheat roots – a rhizotron study. Plant and Soil 2017, 416, 67 -82.
AMA StyleSara Louise Bauke, K. A. Nagel, Nina Siebers, Andrea Schnepf, W. Amelung, M. Koch, Magdalena Landl, D. Hofmann. Macropore effects on phosphorus acquisition by wheat roots – a rhizotron study. Plant and Soil. 2017; 416 (1):67-82.
Chicago/Turabian StyleSara Louise Bauke; K. A. Nagel; Nina Siebers; Andrea Schnepf; W. Amelung; M. Koch; Magdalena Landl; D. Hofmann. 2017. "Macropore effects on phosphorus acquisition by wheat roots – a rhizotron study." Plant and Soil 416, no. 1: 67-82.
Lacking knowledge about the spatial heterogeneity of heterotrophic soil respiration (Rh) hampers the prediction of larger-scale soil CO2 efflux in patchy landscapes. The aim of this study was to establish a cost-efficient method for the rapid and simultaneous assessment of cumulative heterotrophic soil respiration (CO2) at different sample spots. For this purpose, we adapted the laboratory-based, fully-automated Respicond VIII respirometer (Respicond) to detect CO2 emission under field condition, installed the device in two temperate grasslands, and compared the Rh flux data with those obtained using the so-called dynamic chamber method with infrared gas analyzers (IRGA). The results revealed good agreement between both Rh measurements (Slope = 0.89, R2 = 0.99). We conclude that adapting the Respicond for detection of CO2 under field conditions is principally feasible, thus providing a new tool for the simultaneous assessment of CO2 fluxes from different soil ecosystems.
H. Schiedung; S. Bauke; L. Bornemann; G. Welp; N. Borchard; W. Amelung. A simple method for in-situ assessment of soil respiration using alkali absorption. Applied Soil Ecology 2016, 106, 33 -36.
AMA StyleH. Schiedung, S. Bauke, L. Bornemann, G. Welp, N. Borchard, W. Amelung. A simple method for in-situ assessment of soil respiration using alkali absorption. Applied Soil Ecology. 2016; 106 ():33-36.
Chicago/Turabian StyleH. Schiedung; S. Bauke; L. Bornemann; G. Welp; N. Borchard; W. Amelung. 2016. "A simple method for in-situ assessment of soil respiration using alkali absorption." Applied Soil Ecology 106, no. : 33-36.