Klaus Butterbach-Bahl

• Karlsruhe Institute of Technology

Tropical forests play an important role in the greenhouse gas exchange between the biosphere and atmosphere. Despite having the second largest tropical forest globally, the Congo Basin is generally understudied and ground-based greenhouse gas flux data are lacking. In this study, high-frequency measurements spanning 16 months from automated and man...

Machine learning (ML), especially deep learning (DL), is gaining popularity in the agroecosystem modelling community due to its ability to improve the efficiency of computationally intensive tasks. By reviewing previous modelling studies using the PRISMA technique, we present several examples of ML applications in this domain. The potential of usin...

The special issue summarises and highlights key findings of the research unit DASIM funded by the German Research Foundation (DFG) on the process of denitrification. Progress was made in several areas including the development of new and advanced methods to quantify N 2 fluxes such as a new ¹⁵ N gas flux method, enhanced Raman spectroscopy and a ne...

Conservation agriculture, which involves minimal soil disturbance, permanent soil cover, and crop rotation, has been widely adopted as a sustainable agricultural practice globally. However, the effects of conservation agriculture practices on soil N 2 O emissions and crop yield vary based on geography, management methods, and the duration of implem...

Pastoralism is a major way of life in the Sahelian and Sudanian (SaSu) zone of Africa, playing an important social-environmental role through food production and the use of suitable land for seasonal migrations (transhumance). Using Earth Observation (EO) data, we systematically analyze environmental factors—water access, soil properties, topograph...

Riverine CO2 and N2O concentrations have risen since pre-industrial times, but their biogeochemical interactions remain unclear. This study found a positive correlation between N2O and CO2 saturation in fluvial ecosystems, which was absent at high DOC:NO3 ratios. Low DOC:NO3 ratios and high CO2 saturation promote chemoautotrophic nitrification, sug...

Background and aims Organic amendments directly affect soil N transformations, while the direction and magnitude of these effects remain uncertain. Most previous studies through laboratory incubation experiments without plants likely neglected the feedback interactions of plant, thereby limiting the applicability in field conditions. This study aim...

Urease and nitrification inhibitors can reduce ammonia and greenhouse gas emissions from fertilizers and manure but their effectiveness depends on the conditions under which they are used. Consequently, it is essential for the credibility of emission reductions reported in regulatory emission inventories that their effectiveness is assessed under r...

Anthropogenic nitrogen (N) deposition has increased N availability in forests close to human settlements, potentially causing N-limited forests to become N saturated, and influencing forest productivity and future climate. However, the global patterns of N-saturated forests have remained unclear, hindering effective N management. In N-saturated for...

Food, feed, and fiber production needs to increase to support demands of the growing population in Sub‐Saharan Africa (SSA), while soil fertility continues to decline. Intercropping, the cultivation of two or more crop species on the same field, can provide yield benefits and is suggested to positively affect soil organic carbon (C) and nitrogen (N...

Interactions between plants and microorganisms are pivotal for plant growth and productivity. Several plant molecular mechanisms that shape these microbial communities have been identified. However, the importance of nitric oxide (NO) produced by plants for the associated microbiota remains elusive. Using Arabidopsis thaliana isogenic mutants overp...

Nitric oxide (NO) is a key substance in atmospheric chemistry, influencing the formation and destruction of tropospheric ozone and the atmosphere's oxidizing capacity. It also affects the physiological functions of organisms. NO is produced, consumed, and emitted by soils, the effects of soil NO concentrations on microbial C and N cycling and assoc...

Global fluvial ecosystems are important sources of greenhouse gases (CO 2 , CH 4, and 14 N 2 O) to the atmosphere, but their estimates are plagued by uncertainties due to unaccounted spatio-temporal variabilities in the fluxes. In this study, we tested the potential of modeling these variabilities using several machine learning models (ML) and thre...

Tropical forests play an important role in the greenhouse gas exchange between biosphere and atmosphere. Despite holding the second largest tropical forest globally, the Congo basin is generally understudied and ground based greenhouse gas flux data are lacking. In this study, high frequency measurements spanning of sixteen months from automated an...

Methane (CH4) is the second most important atmospheric greenhouse gas (GHG) and forest soils are a significant sink for atmospheric CH4. Uptake of CH4 by global forest soils is affected by nitrogen (N) deposition; clarifying the effect of N deposition helps to reduce uncertainties of the global CH4 budget. However, it remains an unsolved puzzle why...

Nitrogen oxides (NO x ) play an important role for atmospheric chemistry and radiative forcing. However, NO x emissions from the vast northern circumpolar permafrost regions have not been studied in situ due to limitations of measurement techniques. Our goals were to validate the offline analytical technique, and based on this, to widely quantify i...

Intensive fertilization of grasslands with cattle slurry can cause high environmental nitrogen (N) losses in form of ammonia (NH3), nitrous oxide (N2O), and nitrate (NO3⁻) leaching. Still, knowledge on short-term fertilizer N partitioning between plants and dinitrogen (N2) emissions is lacking. Therefore, we applied highly ¹⁵N-enriched cattle slurr...

A complete understanding of the nexus between productivity and sustainability of agricultural production systems calls for a comprehensive assessment of the nitrogen budget (NB). In our study, data from the well-monitored Danish Agricultural Watershed Monitoring Program (LOOP-program; 2013–2019) is used for a quantitative inter-comparison of three...

Straw return to agricultural soils is considered as a key strategy to improve soil organic C (SOC) sequestration and crop production. However, changes in SOC can affect soil N-turnover and associated N2O and NO fluxes, as soil biogeochemical C- and N-cycles are strongly coupled. Understanding how and to what extent N-trace gas emissions per unit cr...

The assessment of cropland carbon and nitrogen (C and N) balances plays a key role in identifying cost-effective mitigation measures to combat climate change and reduce environmental pollution. In this paper, a biogeochemical modelling approach is adopted to assess all C and N fluxes in a regional cropland ecosystem of Thessaly, Greece. Additionall...

Restoration of drained peatlands through rewetting has recently emerged as a prevailing strategy to mitigate excessive greenhouse gas emissions and re-establish the vital carbon sequestration capacity of peatlands. Rewetting can help to restore vegetation communities and biodiversity, while still allowing for extensive agricultural management such...

Climate change poses a significant threat to agriculture, highlighting the need for adaptation strategies to reduce its impacts. Agronomic adaptation strategies, such as changes in planting dates, fertilization, and irrigation, might sustain crop yield. However, their impact on soil greenhouse gas (GHG) emission is unknown under future climate scen...

This study presents a novel plant-soil mesocosm system designed for cultivating plants over periods ranging from days to weeks while continuously measuring fluxes of N2, N2O and CO2. For proof of concept, we conducted a 33-day incubation experiment using six soil mesocosms, with three containing germinated wheat plants and three left plant-free. To...

The ¹⁵N gas flux (¹⁵NGF) method allows for direct in situ quantification of dinitrogen (N2) emissions from soils, but a successful cross-comparison with another method is missing. The objectives of this study were to quantify N2 emissions of a wheat rotation using the ¹⁵NGF method, to compare these N2 emissions with those obtained from a lysimeter-...

Maintaining or even increasing crop yields while reducing nitrous oxide (N 2 O) emissions is necessary to reconcile food security and climate change, while the metric of yield‐scaled N 2 O emission (i.e., N 2 O emissions per unit of crop yield) is at present poorly understood. Here we conducted a global meta‐analysis with more than 6000 observation...

Denitrification plays a critical role in soil nitrogen (N) cycling, affecting N availability in agroecosystems. However, the challenges in direct measurement of denitrification products (NO, N 2 O, and N 2 ) hinder our understanding of denitrification N losses patterns across the spatial scale. To address this gap, we constructed a data‐model fusio...

Methane (CH4) is the second most important atmospheric greenhouse gas (GHG) and forest soils are a significant sink for atmospheric CH4. Uptake of CH4 by global forest soils is affected by nitrogen (N) deposition; clarifying the effect of N deposition helps to reduce uncertainties of the global CH4 budget. However, it remains an unsolved puzzle why...

Global food production faces challenges in balancing the need for increased yields with environmental sustainability. This study presents a six-year field experiment in the North China Plain, demonstrating the benefits of diversifying traditional cereal monoculture (wheat–maize) with cash crops (sweet potato) and legumes (peanut and soybean). The d...

Soil microbial nitrate (NO 3 −) immobilization plays a vital role in enhancing the nitrogen (N) retention in the subtropical montane agricultural landscapes. However, how and why the potential microbial NO 3 − immobilization and the relative contribution of fungi and bacteria vary across different land use types remain still unclear in the subtropi...

Upscaling chamber measurements of soil greenhouse gas (GHG) fluxes from point scale to landscape scale remain challenging due to the high variability in the fluxes in space and time. This study measured GHG fluxes and soil parameters at selected point locations (n=268), thereby implementing a stratified sampling approach on a mixed-land-use landsca...

Since the industrial revolution, accelerated atmospheric nitrogen (N) deposition by human activities have increased N availability in forest ecosystems close to human settlements, potentially causing many nitrogen-limited forests to become nitrogen-saturated, with significant effects on productivity, biodiversity, and biogeochemical cycles. Four de...

Plain Language Summary Biogeochemical models calculate the entire N balance to describe soil N turnover. However, when findings are published, they often focus solely on environmentally harmful N losses like N2O fluxes and NO3− ${{\text{NO}}_{3}}^{-}$ leaching. We argue that it is crucial to publish and communicate the complete N cycle as calculate...

Anthropogenic nitrogen (N) loading alters soil ammonia-oxidizing archaea (AOA) and bacteria (AOB) abundances, likely leading to substantial changes in soil nitrification. However, the factors and mechanisms determining the responses of soil AOA:AOB and nitrification to N loading are still unclear, making it difficult to predict future changes in so...

The Middle East and North Africa (MENA) region has seen remarkable population growth over the last century, outpacing other global regions and resulting in an over-reliance on food imports. In consequence, it has become heavily dependent on grain imports, making it vulnerable to trade disruptions (e.g., due to the Russia-Ukraine War). Here, we quan...

Crop residues are important inputs of carbon (C) and nitrogen (N) to soils and thus directly and indirectly affect nitrous oxide (N2O) emissions. As the current inventory methodology considers N inputs by crop residues as the sole determining factor for N2O emissions, it fails to consider other underlying factors and processes. There is compelling...

The dataset contains yearlong monthly measurements (June 2020 to April 2022) of water quality parameters, CO2, CH4 and N2O concentrations from 23 streams, 3 drainage ditches and 2 wastewater effluent sites within within the Loisach, Schwingbach and Neckar catchments in Germany. The study sites covered various upstream land uses (croplands, wetlands...

The dataset contains yearlong monthly measurements (January 2019 to Febuary 2020) of water quality parameters, CO2, CH4 and N2O concentrations from 59 stream sites within the Kenyan part of the Mara River basin. The study sites covered various upstream land uses (croplands, savanah grasslands and forests) as well as stream orders (1-8). Measurement...

A major societal challenge is to produce sufficient food for a growing global population while simultaneously reducing agricultural nitrogen pollution to within safe environmental boundaries. Here we use spatially-resolved, process-based simulations of cereal cropping systems (at 0.5° resolution) to show how redistribution of nitrogen fertiliser us...

Anthropogenic activities increase the contributions of inland waters to global greenhouse gas (GHG; CO2, CH4, and N2O) budgets, yet the mechanisms driving these increases are still not well constrained. In this study, we quantified year-long GHG concentrations, fluxes, and water physico-chemical variables from 28 sites contrasted by land use across...

Greenhouse gas emissions from headwater streams are linked to multiple sources influenced by terrestrial land use and hydrology, yet partitioning these sources at catchment scales remains highly unexplored. To address this gap, we sampled year-long stable water isotopes (δ18O and δ2H) from 17 headwater streams differing in catchment agricultural ar...

Upscaling chamber measurements of soil greenhouse gas (GHG) fluxes from points to landscape scales remain challenging due to high variability of fluxes in space and time. This study measured GHG fluxes and soil parameters at selected point locations (n=268), thereby implementing a stratified sampling approach on a mixed land-use landscape (~5.8 km2...

Purpose This study presents three contrasting applications using calculation tools for greenhouse gas (GHG) emissions and carbon footprints (C-footprint) that were specifically developed for rice production. This includes a new digital information system for labeling, tracking, and optional auditing of product-specific C-footprints that complements...

High N-fertilizer applications to conventional vegetable production systems are associated with substantial emissions of NH3, a key substance that triggers haze pollution and ecosystem eutrophication and thus, causing considerable damage to human and ecosystem health. While N fertilization effects on NH3 volatilization from cereal crops have been r...

Arable soil continues to be the dominant anthropogenic source of nitrous oxide (N2 O) emissions owing to application of nitrogen (N) fertilizers and manures across the world. Using laboratory and in situ studies to elucidate the key factors controlling soil N2 O emissions remains challenging due to the potential importance of multiple complex proce...

Overuse of fertilizers and irrigation and continuous monocropping is increasingly jeopardizing vegetable production in solar greenhouses as it causes serious soil degradation and the spread of soil-borne diseases. As a countermeasure, the practice of anaerobic soil disinfestation (ASD) has been recently introduced, which is carried out during the s...

Drainage and reduction in precipitation due to climate change have led to global declines in the water table (WT) of pristine peatlands, which have increased ecosystem releases of carbon dioxide (CO 2 ) and nitrous oxide (N 2 O) and decreased emissions of methane (CH 4 ). However, the trade-offs in these changes on net greenhouse gas (GHG) balances...

Anthropogenic activities increase the contributions of inland waters to global greenhouse gas (GHG; CO2, CH4, and N2O) budgets, yet the mechanisms driving these increases are still not well constrained. In this study, we quantified year-long GHG concentrations and fluxes, as well as water physico-chemical variables from 23 streams, 3 ditches, and 2...

The assessment of cropland carbon and nitrogen (C & N) balances play a key role to identify cost effective mitigation measures to combat climate change and reduce environmental pollution. In this paper, a biogeochemical modelling approach is adopted to assess all C & N fluxes in a regional cropland ecosystem of Thessaly, Greece. Additionally, the e...

Excessive water and fertiliser inputs, as well as long-term monocropping, not only cause resource waste and environmental pollution but also drive soil degradation and the occurrence of soil-borne diseases. Anaerobic soil disinfestation (ASD) is a widely used technique in greenhouse vegetable production to replace the use of agrochemicals in disinf...

Anthropogenic activities increase the contributions of inland waters to global greenhouse gas (GHG; CO 2 , CH 4, and N 2 O) budgets, yet the mechanisms driving these increases are still not well constrained. In this study, we quantified year-long GHG concentrations and fluxes, as well as water physico-chemical variables from 23 streams, three ditch...

Urban land use change has the potential to affect local to global biogeochemical carbon (C) and nitrogen (N) cycles and associated greenhouse gas (GHG) fluxes. We conducted a meta-analysis to 1) assess the effects of urbanization-induced land-use conversion on soil nitrous oxide (N2 O) and methane (CH4 ) fluxes, 2) quantify direct N2 O emission fac...

Tropical montane forests store high amounts of soil organic carbon (SOC). However, global warming may affect these stocks via enhanced soil respiration. Improved insight into the temperature response of SOC respiration can be obtained from in and ex situ warming studies. In situ warming via the translocation of intact soil mesocosms was carried out...

Agricultural food production is a main driver of global greenhouse gas emissions, with unclear pathways towards carbon neutrality. Here, through a comprehensive life-cycle assessment using data from China, we show that an integrated biomass pyrolysis and electricity generation system coupled with commonly applied methane and nitrogen mitigation mea...

Globally, organic soils of natural and semi-natural ecosystems have been considered as an important source of atmospheric nitrous oxide (N2O), a powerful greenhouse gas. However, we have little understanding of how and to what extent the magnitude of N2O emissions from such soils is mediated by variation in environmental controls. This knowledge is...

Background Globally, rice systems are a major source of atmospheric CH 4 and for major rice‐producing countries, such as Vietnam, CH 4 as well as N 2 O emissions from agricultural land used for rice production may represent about one‐fourth of total national anthropogenic greenhouse gas (GHG) emissions. However, national‐scale estimates of GHG emis...

Context Accurate reporting of livestock greenhouse-gas (GHG) emissions is important in developing effective mitigation strategies, but the cost and labour requirements associated with on-farm data collection often prevent this effort in low- and middle-income countries. Aim The aim of this study was to investigate the precision and accuracy of sim...

Context Planted grasses are becoming an increasingly important feed resource for tropical smallholder ruminant production; yet, limited research has been conducted to quantify productivity or enteric methane (CH4) production of animals consuming these grasses. Aim An experiment was conducted to assess yields and nutritional attributes of the follo...

Accurate quantification of landscape soil greenhouse gas (GHG) exchange from chamber measurements is challenging due to the high spatial‐temporal variability of fluxes, which results in large uncertainties in upscaled regional and global flux estimates. We quantified landscape‐scale (6 km² in central Germany) soil/ecosystem respiration (SR/ER‐CO2),...

Crop straw application in combination with fertilizer nitrogen (N) dose reduction is recommended to improve crop yields and carbon sequestration in soil. This practice may also promote soil nitrous oxide (N2O) emission, thus partially counterbalancing the expected benefits. However, the full straw return effect on the reduction of soil N2O to dinit...

Livestock are an important source of livelihoods in agricultural systems in sub-Saharan Africa (SSA), while also being the largest source of national greenhouse gas (GHG) emissions in most African countries. As a consequence, there is a critical need for data on livestock GHG sources and sinks to develop national inventories, as well as conduct bas...

Drip fertigation with reduced fertilizer and water inputs has been widely used in greenhouse vegetable production in China. However, farmers usually do not apply additional organic material with a high carbon content, although soil organic carbon (SOC) concentrations are mostly below the optimum level for vegetable production. Returning straw or bi...

Climate change is increasingly putting milk production from cattle-based dairy systems in north sub-Saharan Africa (NSSA) under stress, threatening livelihoods and food security. Here we combine livestock heat stress frequency, dry matter feed production and water accessibility data to understand where environmental changes in NSSA’s drylands are j...

Greenhouse gas fluxes (CO 2 , CH 4 , and N 2 O) from African streams and rivers are under-represented in global datasets, resulting in uncertainties in their contributions to regional and global budgets. We conducted year-long sampling of 59 sites in a nested-catchment design in the Mara River, Kenya in which fluxes were quantified and their underl...

The use of night-time livestock enclosures, often referred to as "bomas", "corrals", or "kraals", is a common practice across African rangelands. Bomas protect livestock from predation by wildlife and potential theft. Due to the concentration of animal faeces inside bomas, they not only become nutrient-rich patches that can add to biodiversity, but...