Wulf Amelung

University of Bonn & Forschungszentrum Jülich GmbH · Institute of Crop Science and Resource Conservation (Soil Science and Soil Ecology) & Agrosphere Institute (Terrestrial Biogeochemistry)

Lake sediments are unique archives of human environment interactions. Lake Prespa is one of the oldest lakes in Europe, lying in the southwestern Balkans and thus on a possible dispersal route of anatomically modern humans from Africa. In this study, we investigated the effects of climate, vegetation and human activity on fire over the last 92,000...

Aims Root exudates contain polymers that form crosslinks and can create a jelly like substance known as mucilage, which adheres to soil and thus promotes the formation of rhizosheaths, i.e. soil that remains attached to the roots after gentle shaking. We hypothesized that rhizosheath formation is optimal at an intermediate chia seed mucilage concen...

Background and aims Paddy management results in frequent redox cycles of the soil and thus changes in the terrestrial iron (Fe) cycle. We intended to test that the increasing duration of paddy management and the increasing frequency of soil redox cycles leave their fingerprint on Fe isotope composition of paddy systems, which could subsequently be...

Antibiotic resistance, along with its dynamics in different environments, has attracted increasing attention because of the potential for resistance gene transfer into human pathogens. Therefore, several researchers have focused on combating the increasing prevalence of antibiotic resistance genes (ARGs) in diverse environments, using various carbo...

Deep‐ploughing far beyond the common depth of 30 cm was used more than 50 years ago in Northern Germany with the aim to break root restricting layers and thereby improve access to subsoil water and nutrient resources . We hypothesized that effects of this earlier intervention on soil properties and yields prevailed after 50 years. Hence, we sampled...

Aims: Mucilage is vital for rhizosheath formation, the soil adhering to plant roots after gentle shaking. We hypothesized that alternating drying-wetting cycles affect mucilage's role in rhizosheath development and soil aggregation within the rhizosphere. To explore this, we employed flax cord as an artificial root model, subjecting it to soils wit...

Crop production often leads to soil organic carbon (SOC) losses. However, under good management practice it is possible to maintain and even re-accumulate SOC. We evaluated how different cropland management techniques affected SOC stocks in the topsoil (0-30 cm depth) of 10 long-term experiments (LTE) in Germany. We found that SOC stocks were parti...

The functions of soils are intimately linked to their three-dimensional pore space and the associated biogeochemical interfaces, mirrored in the complex structure that developed during pedogenesis. Under stress overload, soil disintegrates into smaller compound structures, conventionally named aggregates. Microaggregates (<250 μm) are recognized as...

As located in one of the oldest and driest deserts on Earth, soils in the Atacama Desert are greatly affected by atmospheric dust deposited on soil surface and the related fate of water-dispersible colloids (WDCs, <300 nm). We hypothesize that formation and content of these WDCs change with topography and age of natural soils. To highlight the proc...

Despite previous reports on European growing seasons lengthening due to global warming, evidence shows that this trend has been reversing in the past decade due to increased transpiration needs. To asses this, we used an innovative method along with space-based observations to determine the timing of greening and dormancy and then to determine exis...

Soil records information about past environmental and ecological conditions, yet little is known about mechanisms of memory, transmission of information across space and time, and potential consequences for ecosystem functioning. More systematic inclusion of soil memory in Earth system models can account for complex land surface responses to distur...

The sustainability of life on Earth is under increasing threat due to human-induced climate change. This perilous change in the Earth's climate is caused by increases in carbon dioxide and other greenhouse gases in the atmosphere, primarily due to emissions associated with burning fossil fuels. Over the next two to three decades, the effects of cli...

Agricultural management can influence soil organic carbon (SOC) stocks and thus may contribute to carbon sequestration and climate change mitigation. The soil depth to which agricultural management practices affect SOC is uncertain. Soil depth may have an important bearing on soil carbon dynamics, so it is important to consider depth effects to cap...

There is an urgent need for sustainable intensification and adaptation strategies for European agriculture to face future challenges of food supplies in the face of increased incidences of heat waves and drought conditions. In addition to the cultivation of plants better adapted to drought conditions, one possible strategy could be to use available...

Root restricting layers often hinder crops from accessing the large reservoir of bioavailable mineral nutrients situated in subsoil. This study aims to explore changes in the mean nutrient uptake depth of cereal crops when removing root restricting layers through subsoil management. Subsoil management was performed by deep loosening, cultivation o...

The use of urea as nitrogen (N) fertilizer in agriculture needs to consider environmental, economic and resource conservation aspects because of low N‐use efficiency (NUE). Polymer‐coated urea (PCU) offers an effective way to improve the NUE of urea and to reduce its environmental trade‐offs. However, we lack information on the impact of climate an...

Soil phosphorus (P) is usually hardly present in soluble forms as most of it is strongly bound to minerals. Therefore, transformations of soil colloidal P can play a key role in enhancing soil fertility. Here, we examined water extracts from a chronosequence of soils with 2000 years of paddy rice and 700 years of non-paddy cropping, and fractionate...

Plant root traits play a crucial role in resource acquisition and crop performance when soil nutrient availability is low. However, the respective trait responses are complex, particularly at the field scale, and poorly understood due to difficulties in root phenotyping monitoring, inaccurate sampling, and environmental conditions. Here, we conduct...

Agricultural management can influence soil organic carbon (SOC) stocks and thus may contribute to carbon sequestration and climate change mitigation. The soil depth to which agricultural management practices affect SOC is uncertain. Soil depth may have an important bearing on soil carbon dynamics, so it is important to consider depth effects to cap...

The specific properties of nanoparticles can induce toxic or promoting effects on plant growth. We performed a meta-analysis of 173 studies to evaluate the uptake and accumulation of metallic nanoparticles (MNPs) by crops. Studies on the main cereal/vegetable crops (wheat, tomato, bean, maize, rice and cucumber) and Ag, Zn, Ce, Fe, Cu and Ti contai...

Soil water status, which refers to the wetness or dryness of soils, is crucial for the productivity of agroecosystems, as it determines nutrient cycling and uptake physically via transport, biologically via the moisture-dependent activity of soil flora, fauna and plants, and chemically via specific hydrolysis and redox reactions. Here, we focus on...

Although it has been shown that climate warming has steadily increased the length of the growing season (LGS) in Europe, we present new evidence that this trend reversed during last decade. Warmer European winter and spring weather combined with adequate soil moisture still results in early greening, albeit at slower rates than in the past. However...

Spatial patterns of trace isotope cesium-137 (¹³⁷Cs) can be strongly correlated with soil movement in a landscape, thereby allowing assessments of soil erosion and deposition processes, based on these patterns. Our study assessed how soil organic carbon (SOC) stocks were related to the redistribution of ¹³⁷Cs in prevalent forest and agricultural la...

Microaggregates (<250 µm) are key structural subunits of soils. However, their formation processes, rates, and transformation with time are poorly understood. We took advantage of multiple isotope labelling of potential organic gluing agents and inorganic building units to unravel their role in soil aggregation processes being initiated with and wi...

Rice cultivation requires high amounts of phosphorus (P). However, significant amounts of P fertilizer additions may be retained by iron (Fe) oxides and are thus unavailable for plants. At the same time, rice cultivation has a high demand for silicic acid (Si), reducing Si availability after short duration of rice cultivation. By studying a paddy c...

A sustainable use of soil resources is urgently required to cope with the increasing demand for agricultural products during climate change. To inspire farmers on new soil cultivation methods like subsoil management requires not only yield measures but also nutrient use efficiency measures for which analytical tools are still missing. Stable isotop...

Compost application is a widely recommended agricultural practice to improve soil fertility. As almost all compost is likely polluted with plastic we hypothesize that compost application is a major input pathway of microplastics (MPs) into agricultural soil. To attribute the plastic load of soil to compost application, we investigated MPs in topsoi...

Soil hydrological processes (SHP) support ecosystems, modulate the impact of climate change on terrestrial systems and control feedback mechanisms between water, energy and biogeochemical cycles. However, land-use changes and extreme events are increasingly impacting these processes. In this Review, we describe SHP across scales and examine their l...

Background Even with extensive root growth, plants may fail to access subsoil water and nutrients when root-restricting soil layers are present. Biopores, created from decaying roots or soil fauna, reduce penetration resistance and channel root growth into the deeper soil. Further positive effects on plants result from biopore traits, as the pore w...

Rice cultivation requires high amounts of phosphorus (P). However, significant amounts of P fertilizer additions may be retained by Fe oxides and are thus unavailable for plants. At the same time, rice cultivation has a high demand for Si, reducing Si availability after short duration of rice cultivation. By studying a paddy chronosequence with ric...

The oxygen isotopic composition of phosphate (δ18OP) in soils and surface water bodies has been used to trace terrestrial P inputs into aquatic ecosystems. However, enhanced biological activity in vegetated riparian buffer strips (VBSs) may lead to an alteration of δ18OP values. The objective of this study was to assess whether enhanced biological...

Sodmein Cave in Egypt is an exceptional archive for the study of past human behavior and anthropogenic fire history. Stratified remains of human occupation were excavated, ranging from the Middle Stone Age to the Neolithic. Hearths were repeatedly detected throughout the stratigraphy, with the lowest Pleistocene level having particularly large fire...

Nitrogen (N) cycling in rangeland soils could potentially be controlled by water supply, stocking rates, or a range of other variables, such as ecosystem N stocks. To gauge the relative importance and elucidate possible interactions among these factors, we measured many abiotic variables to identify first‐order controls of δ15N for Patagonia's rang...

The extreme environmental conditions and lack of water on the soil surface in hyperarid deserts hamper microbial life, allowing only highly specialized microbial communities to the establish colonies and survive. Until now, the microbial communities that inhabit or have inhabited soils of hyperarid environments at greater depths have been poorly st...

Sustainable forest management requires understanding of ecosystem phosphorus (P) cycling. Lang et al. (2017) [Biogeochemistry, https://doi.org/10.1007/s10533-017-0375-0] introduced the concept of P-acquiring vs. P-recycling nutrition strategies for European beech (Fagus sylvatica L.) forests on silicate parent material, and demonstrated a change fr...

The application of phosphorus (P) fertilizers inevitably contributes to the accumulation of trace elements, such as uranium (U), in agricultural soils. The fertilizer-derived U accumulation was first reported in Rothamsted Research in 1979. In the present study, we expand this key early research by evaluating the fertilizer-derived U accumulation i...

Organic soils (Histosols) are formed by accumulation of incompletely decomposed organic matter. This chapter introduces the classification, genesis and properties of organic soils and potential management. Organic soils comprise histosols with folic horizons formed in cold climates as well as fens and bogs with or without contact with minerotrophic...

Microaggregates (<250 μm) are key structural subunits of soils. However, their formation processes, rates, and transformation with time are poorly understood. We took advantage of multiple isotope labelling of potential organic gluing agents and inorganic building units to unravel their role in soil aggregation processes being initiated with and wi...

Specific aspects of human life only become visible at specific spatial and temporal scales, while remaining invisible at others. Observations at the global scale tend to overlook regional developments and vice versa. Scales of time as well as scales of space are nested, and as a matter of necessity, observations always have a temporal, spatial, and...

Mycotoxins are secondary metabolites produced by specific fungi that have harmful effects on animals and humans. Worldwide more than 300 different mycotoxins are already known, frequently with concentrations in harvest products exceeding acceptable limits. Nevertheless, although these compounds have extensively been studied in food and feed, only l...

Livestock integrated land use systems are considered as viable options for enhancing soil organic carbon (SOC) sequestration in a changing climate. This study assessed the influence of water deficit and livestock stocking density on soil carbon stocks. A total of 101 matching data were extracted from map layers of water deficit and livestock stocki...

Amazonian Dark Earths (or terra preta de índico) are known as highly fertile soils that can maintain elevated crop yields for centuries. While this fertility was frequently ascribed to the presence of black carbon, the availability and colloidal binding of major nutrients received limited attention. We examined the size distribution and the element...

Nature conservation and restoration in terrestrial ecosystems is often focused on increasing the numbers of megafauna, expecting them to have positive impacts on ecological self-regulation processes, and biodiversity. In sub-Saharan Africa, conservation efforts also aspire to protect and enhance biodiversity with particular focus on elephants. Howe...

The Atacama Desert (Chile) is one of driest places on Earth, with a hyper-arid climate and less than 2mm yr⁻¹ precipitation; nevertheless, it has experienced rare periods of sporadic rainfall. These periods shortly enhanced vegetation growth and microbial activity, which must have utilized major nutrients such as phosphorus (P). However, any biolog...

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 Ama...

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 th...

Soil aggregates may stabilize carbon at mineral surfaces and in the interior, but resolving such micro-scale carbon (C) turnover at a scale of soil aggregates <2mm is challenged by C contaminations during sample preparation such as from resin embedding. Here we introduce a novel C-free embedding method using silica gel for water glass formation, an...

Aims Agricultural soils in Germany store 2.54 Pg of organic carbon (C). However, information about how and when this C entered the soils is limited. This study illustrates how depth profiles of organic matter can shed light on different entry paths of organic C. Methods Machine learning was used to explain total organic C (TOC), C:N, particulate o...

The physical arrangement of compounds in soil microaggregates is controlling many ecosystem functions such as soil stability and C sequestration. However, little is known about the spatial arrangement of organic and inorganic compounds in soil microaggregates, due to the lack of in-situ analyses of undisturbed material. We hypothesized that microag...

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 labelling, but the degree to which plants preserve the δ18OP value of the P source is unclear. We hypothesised that the source signal will be preserved in roots rather than shoo...

Soil organic matter (SOM) accumulation is different in certain soil groups with differences in parent material, degree of weathering and mineral composition. These differences are modulated by climatic factors, but also by pedogenesis, in particular by the formation of reactive mineral surfaces, by soil aggregation, as well as by translocation proc...

Background and aims: Phosphorus (P) is an essential element for crop growth. However, while links of P turnover in soils to carbon (C) and nitrogen (N) availability have been described, it remains to be clarified how combinations of fertilizer C and N additions affect stocks and cycling of distinct P fractions at different soil depths. The objectiv...

Peatlands comprise major global stocks of soil organic carbon (SOC). Many degraded peatlands are currently being restored, but little is known to which degree former disturbances leave a ‘legacy’ in such restored peatlands, and subsequently how this impacts their response to global change. Our aims were to investigate if after 20 years of restorati...

31P nuclear magnetic resonance (NMR) spectra can be biased due to the hydrolysis of labile P species during sample treatment and NMR analysis. This paper offers an approach to circumvent this problem by performing sample preparation and analysis in 18O-enriched medium. Heavy 18O isotope atoms were introduced into the resulting artificial hydrolysis...

The global decline in invertebrate diversity requires urgent conservation interventions. However, identifying priority conservation areas for invertebrates remains a significant challenge. We hypothesized that aligning the conservation of invertebrate biodiversity with climate change mitigation offers a solution. As both soil carbon storage and inv...

Although the Atacama is the oldest and most continuous dry desert on Earth, organic matter (OM) is ubiquitous in its surface sediments. Today, vegetation growth is restricted to the Coastal Cordillera and the Andean foothills, which are predominantly supplied by fog or rainfall. The sources of OM in topsoils of hyperarid regions and deep sediments...

To maintain and improve soil fertility, compost application is a widely recommended practice. We hypothesized that this practice is, however, also a main entry path for plastic into soil. Hence, we i) quantified the prevalence of plastic in eight composts from different composting plants and hardware stores to derive estimations about related plast...

Lake sediments can provide useful archives to reconstruct past vegetation changes or fire history. To comprehend how vegetation and fire history have correlated during the last 130,000 years, we used two lake sediment records with known patterns of pollen and botanical macro remains and supplemented this data by analyses of lignin-derived phenols a...

Information on the bioavailability and -accessibility of subsoil phosphorus (P) and how soil moisture affects its utilization by plants is scarce. The current study examined whether and to which degree wheat acquires P from subsoil allocated hydroxyapatite and how this could be affected by soil moisture. We investigated the 33P uptake by growing wh...

Dissolved and colloidal phosphorus (P) represent the mobile P fractions in soils, but their role in P cycling in forests is still largely unclear. In this study of four calcareous forest soil profiles, the elemental compositions of different size fractions of water dispersible colloids (WDC) were investigated by asymmetric field flow fractionation....

Aims Magnesium (Mg) deficiency is detrimental to plant growth. However, how plants respond to Mg deficiency via regulation of Mg uptake and allocation is yet not fully understood. In this study, we tested whether Mg isotope compositions (δ26Mg) associated with Mg mass balance of the plants could be used as an indicator to trace Mg uptake and subseq...

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 G...

Sustainable soil carbon sequestration practices need to be rapidly scaled up and implemented to contribute to climate change mitigation. We highlight that the major potential for carbon sequestration is in cropland soils, especially those with large yield gaps and/or large historic soil organic carbon losses. The implementation of soil carbon seque...

Background: In search for more sustainable crop production, the subsoil has recently come into focus as considerable reservoir of nutrients and water. Aims: Dimensions of subsoil phosphorus (P) reserves are yet largely unknown but crucial for identifying regions suitable to include subsoil into sustainable management strategies. Methods: We analyze...

The data herein were used to trace the source and depth of nutrient uptake in two mountainous temperate forest ecosystems in southern Germany (Conventwald/Black Forest and Mitterfels/Bavarian Forest). Presented are phosphorus (P) concentrations from various P fractions of soil, saprolite, weathered bedrock and unweathered bedrock samples from drill...

Primary productivity of forest ecosystems depends on the availability of plant‐essential mineral nutrients. Because nutrient demand of trees often exceeds nutrient supply from rock, tree nutrition is sustained by efficient reutilization of organic‐bound nutrients. These nutrients are continuously returned from trees to the forest floor in litterfal...

River deltas are frequently facing salinity intrusion, thus challenging agricultural production in these areas. One adaption strategy to increasing salinity is shrimp production, which however, heavily relies on antibiotic usage. This study was performed to evaluate the effect of increasing salinity on the dissipation rates of antibiotics in tropic...

Woody encroachment is increasingly threatening savanna ecosystems, but it remains unclear how this is driven by different land tenures and management systems. In South Africa, communal land is mainly managed under continuous grazing, while commercial land is under rotational grazing. We hypothesize that woody encroachment has increased since the en...