Soils are one of the major players in the global carbon (C) cycle and climate change by functioning as a sink or a source of atmospheric carbon dioxide (CO2). The largest terrestrial C reservoir in soils comprises two main pools: organic (SOC) and inorganic C (SIC), each having distinct fates and functions but with a large disparity in global research attention. This study quantified global soil C research trends and the proportional focus on SOC and SIC pools based on a bibliometric analysis. Research on soil C pools started in 1905 and has produced over 42,000 publications (> 1.6 million citations). Although the global C stocks down to 2 m depth are nearly the same for SOC and SIC, the research has dominantly examined SOC (> 96% of publications and citations) with a minimal share on SIC (< 4%). Approximately 39% of the soil C research was focused on climate change. Despite poor coverage and publications, the climate change-related research impact (citations per document) of SIC studies was higher than that of SOC. Machine learning, biochar, soil properties, and climate change were the recent top trend topics for SOC research (2018-2022), whereas soil acidification, organic C, climate change, and Holocene were recent trends for SIC. SOC research was contributed by 150 countries compared to 85 for SIC. As assessed by publications, soil C research was mainly concentrated in a few countries, with only 10 countries accounting for 75% of the research. China and the USA were the major producers (44%), collaborators (36%), and funders of soil C research. SIC is a long-lived soil C pool with a turnover rate of more than 1000 years in natural ecosystems but intensive agricultural practices have accelerated SIC losses, making SIC an important player in global C cycle and climate change. The lack of attention and investment towards SIC research could jeopardize the ongoing efforts to mitigate climate change impacts to meet the 1.5-2.0 oC targets under the Paris Climate Agreement of 2015. This study calls for expanding the research focus on SIC and including SIC fluxes in C budgets and models, without which the representation of the global C cycle is incomplete.

How to cite: Raza, S., Irshad, A., Margenot, A., Zamanian, K., Ullah, S., Kurganova, I., Zhao, X., and Kuzyakov, Y.: Inorganic carbon: an overlooked pool in global soil carbon research  , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2926, https://doi.org/10.5194/egusphere-egu24-2926, 2024.

Evaluating SOC biogeochemical stability is key to better predict the impact of SOC on both climate mitigation and soil health. This evaluation can be conducted using SOC partition schemes that allow us to quantify SOC fractions with different biogeochemical stability. However, most of these schemes are costly or time consuming and cannot be implemented on large sample sets. Two exceptions are  the widely used physical fractionation protocol allowing to separate particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) and the emerging thermal fractionation protocol distinguishing active SOC (C_a; MRT ~30 years) from stable SOC (C_s; stable at a centennial timescale).

Here, we use analyzes conducted on samples from the French soil monitoring network (RMQS) to compare the results of thermal fractionations (C_a/C_s) performed on ca. 2000 samples, and physical fractionations (POC/MAOC) performed on ca. 1000 samples. Our results show that MAOC and C_s from one side and POC and C_a from the other side have different sizes. The most biogeochemically stable fractions (C_s and MAOC) are mostly influenced by soil characteristics whereas land cover and climate influence more substantially POC and C_a. However, the more stable fractions provided by both fractionation schemes (respectively the more labile fractions) do not have the exact same environmental drivers. Our results therefore suggest that both fractionation scheme gives complementary results. The relative contribution of these fractionation schemes to the evaluation of soil functions and OC stock evolution remains to be evaluated on soil monitoring networks and constitutes a promising research avenue.

How to cite: Delahaie, A. and the Freacs team: Investigating the complementarity of thermal and physical soil organic carbon fractions, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1063, https://doi.org/10.5194/egusphere-egu24-1063, 2024.

Land-use changes affect soil organic carbon (SOC) stocks over decades. However, IPCC default for greenhouse gas emissions reporting suggests a simple linear SOC stock change over 20 years only. Using process-based modelling approaches such as RothC to describe SOC dynamics after land-use change requires model validation. However, there are only few long-term field experiments where SOC stocks have been observed long enough to get sufficient data for such a model validation. This lack of data makes validating models for large-scale use challenging.

Based on empirical data from over 3000 sites from the German Agricultural Soil Inventory we selected 204 sites with land-use change history within the last 60 years and created an artificial data-set using a reciprocal modeling approach. This approach utilizes machine learning models trained on sites under permanent land use to predict SOC stocks for similar sites where the land use had been changed. In addition, we extracted further empirical data from over 30 sites with land-use change in the temperate zone from a comprehensive meta-analysis.

These two datasets were used to test the ability of the well-known SOC model RothC to simulate land-use change effects on SOC stocks. In these tests, we use the observed or predicted SOC stocks assumed at equilibrium to model the carbon input under permanent land use and corresponding SOC dynamics after land-use change. These modelled SOC dynamics are then compared with observed SOC stocks after land-use change.

We will discuss opportunities and challenges of using process-based models to describe SOC dynamics after land-use change on regional to national scale.

How to cite: Seitz, D., Dechow, R., Emde, D., Schneider, F., and Don, A.: Soil organic carbon dynamics after land-use change – combining process-based modelling with machine learning, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7661, https://doi.org/10.5194/egusphere-egu24-7661, 2024.

Drylands are important carbon pools and are highly vulnerable to climate change, particularly in the context of increasing aridity. However, there has been limited research on the effects of aridification on soil total carbon including soil organic carbon and soil inorganic carbon, which hinders comprehensive understanding and projection of soil carbon dynamics in drylands. To determine the response of soil total carbon to aridification, and to understand how aridification drives soil total carbon variation along the aridity gradient through different ecosystem attributes, we measured soil organic carbon, inorganic carbon and total carbon across a ~4000 km aridity gradient in the drylands of northern China. Distribution patterns of organic carbon, inorganic carbon, and total carbon at different sites along the aridity gradient were analyzed. Results showed that soil organic carbon and inorganic carbon had a complementary relationship, that is, an increase in soil inorganic carbon positively compensated for the decrease in organic carbon in semiarid to hyperarid regions. Soil total carbon exhibited a nonlinear change with increasing aridity, and the effect of aridity on total carbon shifted from negative to positive at an aridity level of 0.71. In less arid regions, aridification leads to a decrease in total carbon, mainly through a decrease in organic carbon, whereas in more arid regions, aridification promotes an increase in inorganic carbon and thus an increase in total carbon. Our study highlights the importance of soil inorganic carbon to total carbon and the different effects of aridity on soil carbon pools in drylands. Soil total carbon needs to be considered when developing measures to conserve the terrestrial carbon sink.

How to cite: Ren, Z., Li, C., Fu, B., Wang, S., and Stringer, L. C.: Effects of aridification on soil total carbon pools in China's drylands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2759, https://doi.org/10.5194/egusphere-egu24-2759, 2024.

Post mining ecosystems are severally degraded.  This is particularly true for soils which are either excavated or buried and replace by overburden which differ remarkably, from normal soils. Despite these severe degradation, post mining soils of numerals opportunities: they are valuable secondary habitat for rare and endangered species, and soils developing in these areas are able to sequester carbon in much higher rate than soils in surrounding landscape.. Here we compare effect of reclaimed and unreclaimed sites on provisioning ecosystem services in Sokolov (Czech Republic) and on climatic gradient across USA. In suitable substrates, the succession is driven mainly by site topography. In sites which were leveled grassy vegetation develops. In sites where original wave like topography was preserved the ecosystem develops towards shrubs and forest. Reclaimed and unrecaimed forest sites have similar development of canopy cover,   stems number gradually decreased with age in reclaimed sites and increased in succession, in 20 year both reaching the same density.  Tree biomass was higher in young reclaimed sites, in sites 30 years old or older tree biomass in succession sites was comparable or higher than in reclaimed sites.  Initial rate of soil carbon storage in reclaimed sites namely those planted by alder was faster than in succession sites but it decrease with plot age.  In unclaimed sites, the rate of C storage increase and peaked in site 20-30 years old. Amount of C stored in unreclaimed sites c 50 years old is comparable to alder plantations of the same age.  Alder plantation of intermediate age store more water than unreclaimed sites but water budget is similar due to higher water demand of alder.  In leveled sites where grassland establish, reclaimed sites are slightly higher in all studied parameters. In conclusion, development of key ecosystem process is fasted in reclaimed sites but latter on difference disappear. The reasons are, soil   leveling, promote soil compaction, which slows root growth. Focus on achieving a close cannopy often lead to dense three stand which limit a light availability for trees. This is even supported by leveling and homogenous pattern of planting which lead to one layer cannopy, compare to multi-layer cannopy in unreclaimed sites. Also planting N fixers, my contribute, to this slow down, as nitrogen fixing plant often fixed nitrogen even in conditions when nitrogen is already plentiful in soil. This cause additional energy expense for the trees.

Comparison of benefits of reclamation and spontaneous ecosystem development vary depending on climatic conditions and target ecosystem. For example, in dry cold conditions when target is grassy vegetation such as short grass prairie in Wyoming (USA), to reclamation practices show often much better results than unassisted ecosystem development. In contrary in wet warm climate, when broadleaf forest is a target (e.g. in Eastern USA), unassisted ecosystem development often shows better results in many parameters namely in long run.  These results show that we should try to better understood naturel processes of ecosystem development so we can implement them in improvement of reclamation technologies.

How to cite: Bartuška, M. and Frouz, J.: Natural regeneration as restoration strategy to restore functional soils and ecosystems in post mining sites, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-3229, https://doi.org/10.5194/egusphere-egu24-3229, 2024.

We studied the effect of grazing on carbon sequestration in semi-natural grasslands.  The study was conducted on three farms with known history of land use in W Iceland. On each farm, we located an intensively (IG) and an extensively (EG) grazed site, which both had been constantly grazed for centuries, and a parallel site were grazing had been excluded (NG) for over 50 years. We measured net ecosystem exchange (NEE), ecosystem respiration and normalized difference vegetation index (NDVI) on a regular basis over the growing season. Samples were taken from 60 cm deep soil profiles for analysis of soil organic carbon (SOC). The grazed sites showed significantly more negative NEE than the NG sites, indicating more carbon dioxide uptake on the grazed sites compared to the NG sites. NDVI was also significantly higher on the grazed sites. On all farms, the total SOC content was higher in the grazed sites than in the parallel NG sites. The study indicates that cessation of grazing decreases productivity and carbon dioxide uptake in a semi-natural grassland in Iceland, as well as SOC content in the soil. Historically, all the NG sites in the study had the same grazing history as the continuously grazed sites until grazing exclusion. The measured lower SOC on the NG sites seems to indicate that, without grazing, SOC is lost with time and/or grazing is needed to maintain SOC in these grasslands.

How to cite: Thorhallsdottir, A. G. and Gudmundsson, J.: Carbon dioxide fluxes and soil carbon storage in relation to long-term grazing and grazing exclusion in Icelandic semi-natural grasslands, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-8473, https://doi.org/10.5194/egusphere-egu24-8473, 2024.

Dissolved organic carbon (DOC) is a highly active carbon pool which can easily be utilized by soil microbes and is thereby a crucial fraction of the soil carbon cycle. Occlusion within soil aggregates is one important stabilization mechanism of DOC in the soil and is affected by various factors including soil management and site-specific conditions. However, details about this mechanism and its regulating factors are still largely unclear. Thus, this study aims to investigate the stabilization mechanism of DOC in soil aggregates under different soil managements across varying soil textures (fine, medium, and coarse). In the study, the soil managements were categorized into three different systems depending on the degree of conservation measures implemented on the farms: state-of-the-art system (standard), conservation systems (pioneer) which were primarily characterized by intensive use of cover cropping together with crop diversification and rotation, and semi-natural grassland (reference). We employed a combination of ultrasonication and online UV-visible spectroscopy to examine the concentration of DOC released from soil aggregates decayed. The experimental setup followed the theory that the duration of low-amplitude ultrasonication energy correlates with higher aggregate stability (resistant to decay), which in return affects the stability of DOC. Influential factors were assessed from relationships with soil physico-chemical and biological characteristics. Based on the observed release pattern, the study deduced that DOC was stabilized within soil aggregates across three different stability levels: low, moderate, and high. 

The results revealed that soil management systems exerted a significant effect on DOC in moderately and highly stable aggregates. Standard systems exhibited the lowest DOC concentration, while reference systems demonstrated the highest concentration. A significant effect of soil texture was found only at the moderate aggregate stability level where coarse soil displayed the lowest DOC concentration. Contrastingly, neither soil management systems nor soil texture had a significant effect on DOC concentration at the low aggregate stability level. The stabilized DOC within moderately stable aggregates, as evidenced by DOC concentration at the moderate level of aggregate stability, exhibited more pronounced correlations with soil microbial variables (i.e., microbial biomass C and ergosterol) than with soil texture as identified through particle size distribution. Therefore, our results suggest that changes induced by soil management, particularly in microbiological attributes, have a more crucial role on the stabilization of DOC in highly stable aggregates than site-specific conditions such as soil texture. Furthermore, the application of low-energy ultrasonication in this study enables the differentiation of soil managements, even within arable systems, in an on-farm setting.

How to cite: Sae-Tun, O., Rosinger, C., Bodner, G., Mentler, A., Mayer, H., Huber, S., and Keiblinger, K.: On-farm soil management distinctly influences the stabilization of dissolved organic carbon within soil aggregates, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-15383, https://doi.org/10.5194/egusphere-egu24-15383, 2024.

In Northeast China, conventional tillage practices involve removal of crop residue after harvest and prior to moldboard plowing; this has been shown to cause a decline of soil organic carbon (SOC) and degradation of Black soils (Mollisols). Conservation tillage, particularly no tillage (NT), has been suggested to be an effective practice to control soil erosion and increase the SOC content. Hence, we established an experiment (since 2001) to evaluate how a combination of different tillage and cropping systems could improve SOC in black soils. The total SOC storage, SOC fractions (physical and chemical), SOC stability were assessed to evaluate the effects of tillage and cropping system. Our results shows that: 1) different tillage and cropping system combinations had different effects on SOC storage; NT combined with continuous maize had the highest SOC storage among all treatments; 2) The effects of tillage on aggregate size and OC concentration mainly occurred in the surface layer (0–5 cm) while the effect of cropping system on aggregate size and OC concentration mainly occurred at deeper depths; 3) NT increased the recalcitrant carbon pool in surface layer showing the critical need for returning crop residues to maintain long-term SOC storage; 4) SOC mineralization (biological stability) appears to be related to the SOC proportion in the light fraction; 5) More than half of the increase in SOC storage due to NT existed as microbial necromass carbon storage under continuous maize which was higher than maize-soybean rotation. Our study shows that in black soils (Northeast China), NT and appropriate cropping systems can not only halt soil degradation caused by poor management but can induce substantial increases in SOC which is beneficial for SOC long-term sequestration.

How to cite: Zhang, Y., Liang, A., Zhang, X., Li, X., Gregorich, E., and McLaughlin, N.: Effects of conservation tillage on soil organic carbon storage, fractions and stability in Black soil, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-54, https://doi.org/10.5194/egusphere-egu24-54, 2024.

Phosphorus (P) is a crucial nutrient for plant growth, its limitation reduces plant and microbial biomass, affecting soil organic carbon (SOC) sequestration. Changes in soil P content may influence microbial composition, shaping pathways in the carbon (C) and nitrogen (N) cycles and impacting greenhouse gas emissions. In this lab incubation experiment we investigate the impact of different P fertilisation levels in three European long-term experiments (LTE) on N and C transformation processes and greenhouse gas fluxes in agricultural soils using stable isotope techniques (¹⁵N and ¹³C). The study is part of the EJP SOIL project “ICONICA” (Impact of long-term P additions on C sequestration and N cycling in agricultural soils).

The soil samples derived from Johnstown Castle, JC (grassland soil, Ireland), Lanna Skara, LS (arable soil, Sweden) and Jyndevad, JY (arable soil, Denmark). Two P levels were examined from each LTE: low P (0 kg P/ha and year) and high P additions (different P application rates among LTEs). The soils were mixed with ¹³C- and ¹³C¹⁵N- labelled maize biomass, respectively, and received ammonium nitrate (NH₄NO₃) in the ¹³C treatment as ¹⁵NH₄NO₃ and NH₄¹⁵NO₃, respectively, and unlabelled NH₄NO₃ in the ¹³C¹⁵N treatment. Soil and gas samples were taken 0, 1, 3, 7 and 10 days after addition of NH₄NO₃ and were analysed for ⁽¹⁵⁾NH₄⁺-N, ⁽¹⁵⁾NO₃^--N, organic ⁽¹⁵⁾N, organic ⁽¹³⁾C contents as well as for nitrous oxide (⁽¹⁵⁾N₂O), carbon dioxide (⁽¹³⁾CO₂), and methane (CH₄) fluxes.

Preliminary findings display clear differences among the three LTEs as well as the two P levels. Regarding the impact of P fertilisation history: JC soil exhibited elevated CO₂ emissions at high P compared to low P level. Significantly, high P levels showed higher CH₄ uptake rates in JC and JY soils compared to the respective low P levels. JY had the highest N₂O emissions, while JC had the lowest. JC had higher NH₄-N values than LS. The highest NO₃-N values were measured in JC, and the lowest in JY. In JC, higher NO₃-N values were measured in high P compared to low P.

The results so far underscore the complex interactions within the carbon-nitrogen-phosphorus cycles under varying P inputs. Further analyses and interpretations are in progress.

How to cite: Dannenberg, L., Eckhardt, C., Müller, C., and Kleineidam, K.: Long-Term Phosphorus Fertilisation: Effects on Nitrogen and Carbon Cycle Dynamics and Greenhouse Gas Fluxes in European Agricultural Soils , EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-1422, https://doi.org/10.5194/egusphere-egu24-1422, 2024.

The Ntrace tool was developed as a flexible ¹⁵N analysis tool to determine gross nitrogen (N) transformations. Since the development of the tool, it has been applied to many ecosystems world-wide as documented in more than 190 peer-reviewed publications. Over time, the tool has evolved to become much more flexible including different pools and determining more transformation rates. Up until now, the focus has been on the N cycle. However, the N and carbon (C) cycle are closely connected. Considering both cycles concomitantly provides a more comprehensive understanding of how elements move through the system. Thus, the next step in the development of the Ntrace tool includes connecting the N and C pools (CNtrace) in order to simultaneously quantify gross N and C transformations based on the observed ¹⁵N and ¹³C dynamics. Data from specifically designed experiments, using either labelled organic matter or C₄ plants in a C₃ soil, with the addition of differentially ¹⁵N labelled mineral fertilizer will be used for the development of the CNtrace tool. The theoretical background and the various development steps will be presented.

How to cite: Jansen-Willems, A., Kleineidam, K., Clough, T., Dannenberg, L., and Müller, C.: Development CNtrace tool, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-2093, https://doi.org/10.5194/egusphere-egu24-2093, 2024.

Grasslands are a major sink of organic carbon and for that reason are interesting as a means to achieve national and international climate goals. Grassland renovation (reseeding or conversion to arable land) is a common measure to counteract yield declines in intensively managed agricultural grasslands. The destruction of the sod that accompanies this practice induces a strong increase in mineralization of soil organic carbon and can therefore be a major source of nitrate (NO₃) leaching and emissions of carbon dioxide (CO₂) and nitrous oxide (N₂O).

Most farmers prefer reseeding in autumn instead of spring because of better establishment of the sward and low weed infestation. However, limited crop nitrogen (N) demand during autumn increases the risk of NO₃ leaching and N₂O emissions. Potentially, such N losses could be mitigated by measures such as reducing tillage intensity, reducing fertilizer N application, or applying nitrification inhibitors. In 7 different experiments, we studied the effect of various grassland renovation practices on soil N cycling, greenhouse gas emissions, and nitrate leaching. We hypothesized (i) that conversion to arable land leads to greater CO₂ and N₂O losses than the reseeding of grassland; (ii) that reseeding in autumn causes enhanced risk of NO₃ leaching during winter; and (iii) that these losses can be mitigated by reducing tillage and/or N application rates.

Results show that NO₃ concentrations in groundwater after harvest were higher for observed after autumn reseeding combined with mitigation strategies than for reseeding in spring. This implies that confining the renewal of grassland to spring season could be a viable strategy to mitigate NO₃ leaching. Emissions of N₂O varied between experiments and could generally be linked to precipitation events and agricultural management (fertilization and renovation). Grassland renovation led to higher N₂O (and CO₂) emissions, but the effects of mitigation practices were inconsistent. The results from these experiments will be discussed in more detail. Mitigation strategies for N₂O are less straightforward than those for nitrate leaching.

How to cite: Ros, M., van 't Hull, J., and Velthof, G.: Greenhouse gas emissions and nitrate leaching as a result of grassland renovation practices, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-18694, https://doi.org/10.5194/egusphere-egu24-18694, 2024.

Land degradation appears today as a major issue for feeding humans, whose population on Earth is still increasing. Such issues are particularly acute in semi-arid regions like the Sahel, where, in addition, soils are already poor in nutrients and carbon. Wind erosion is one of the processes likely to cause soil depletion of nutrients and carbon in this region, thus potentially leading to land degradation. However, there is little scientific literature providing quantitative estimates of soil losses of nutrients and carbon through the windblown sediments, particularly for the Sahel.

We monitored the horizontal flux of windblown sediments (collected every 2 weeks in MWAC sand-traps) for the main land use types of Western Sahel in the Peanut Basin of Senegal: a field (bare, then cropped with groundnut) (2020-2021), 4 fallows (2022/2023), and 4 millet fields (2023/2024) to characterize differences in windblown sediment fluxes due to land management (e.g. management of crop residues, grazing pressure, …). Each plot was about 1 ha, and had 5 masts of 5 MWAC each, from 5 cm to 80 cm above ground level. During these experiments, we also monitored vegetation characteristics (every week) and meteorological variables (at 5-minutes resolution).

We then carried out analyses on the windblown sediments collected in the sand traps for the bare/groundnut field (the amounts of sediments collected in the fallows were too low to perform such analyses, and the erosive period, which extends from January to April in Western Senegal, just started in early 2024 for the millet fields experiment).

Our first results show that the horizontal flux of windblown sediments is much larger for a bare/groundnut field (around 40 t/ha/year) than for fallows (0.03 to 0.80 t/ha/year). The results also suggest that differences in land management among fallows (e.g. age, woody cover) may have an impact on this horizontal flux.

Additionally, the orders of magnitude of the organic C, total N and available (Olsen) P concentrations of the horizontal (saltation) flux from the bare/groundnut field are respectively approximately 0.22%, 0.02%, and 8 ppm, thus larger than the concentrations of the topsoil, that are respectively 0.15 %, 0.01 % and 7 ppm. These values compare well with those existing in the literature (e.g. for Niger), and confirm an enrichment of the horizontal flux (by a factor of 1.1 to 1.8) in soil carbon and nutrients compared to the topsoil. A rough estimate of organic C losses from the monitored field of 1 ha would be about 80 kg/year, and 8 kg/ha and 0.32 kg/ha for N and available P, respectively.

To better characterize the composition of windblown sediments, we also plan to carry out microbiological analyzes to determine the composition of the microbial communities (bacteria and fungi) they contain. Indeed, these microbial communities play a role in the biogeochemical cycle of nutrients and in the storage of carbon in the soil, thus potentially impacting their fertility.

We thank the IMAGO/LAMA analytical laboratory of Dakar for the analyses of the composition of the sediment samples.

How to cite: Pierre, C., Rajot, J. L., Bonneval, P.-M., Raynal, P.-A., Tall, A., Faye, I., Fall, D., and Tine, A.: Nutrients and carbon losses due to wind erosion in Sahelian Senegal, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7793, https://doi.org/10.5194/egusphere-egu24-7793, 2024.

Improved tillage practice plays a positive role in restoring degraded cropland, maintaining crop productivity, and mitigating climate change, which has been proposed as a sustainable agricultural technology. Based on a long-term experiment in black soil area of Northeast China, effects of different tillage practices on soil organic carbon (SOC) and nutrient content were explored, and ecological and economic benefits were also evaluated. Three tillage practices were included: conventional tillage with complete removal of residue (CT), moldboard plowing with residue return (MP) and no-tillage with residue return (NT). As the trial period increased, the SOC content of the CK decreased in the 0-20 cm soil layer, while the total nitrogen (TN) content remained. Residue return treatments (MP and NT) increased SOC and TN content. The SOC and TN were uniformly distributed in the 0-20 cm soil layer of MP, whereas the SOC and TN increased significantly in the 0-5 cm soil layer of NT, especially during the 5-8 years of the experiment. The total phosphorus (TP) and total potassium (TK) contents of all treatments slowly increased over time, and there was no significant difference among treatments. Compared with CT, NT could reduce N₂O emissions and absorb more CH₄, whereas MP significantly increased CO₂ emissions from soil. Moreover, NT led to both the lowest GHG emissions from soil (GWP_GHG) and agricultural inputs (AIGHG), thus reduced approximately 40% carbon footprint (CF) compared to CT. However, no significant difference in maize yield and net ecosystem ecological benefit (NEEB) were observed among three tillage practices, although MP and NT showed lower investments during maize production than CK. In conclusion, NT could not only enhance the SOC and nutrient content but also minimize CF while ensuring economic benefit from a long-term perspective. Long-term NT can be implemented in Northeast China and similar agro-eco-regions around the world.

How to cite: Zhang, Y. and Liang, A.: Effects of long-term residue return on nutrient content, ecological and economic benefits of black soil in Northeast China, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-6534, https://doi.org/10.5194/egusphere-egu24-6534, 2024.

There is scarce information about toxic effects, environmental dynamics and even toxic levels or regulations, mainly in soils, of several elements widely used in agriculture and industry. These so called elements “of emerging concern” have not been studied, mainly regarding their environmental effects or relationships. By the other hand, tons of pharmaceuticals are liberated by effluents of the wastewater treatment plants to the environment and agricultural fields daily. As study case, we have selected an important area in Spain that is affected by high anthropogenic pressures.

The target area of study the alluvial plain between the rivers Turia and Jucar (Valencia, SPAIN), with an extension of 486 km², which is characterized by its dense network of channels and ravines for irrigation one of the most productive agricultural areas of Spain. This area includes a wide zone of rice farming and a Natural Park (L’Albufera). In this study area, 33 sampling zones were selected covering the different water sources and agricultural types, to monitor the distribution of the levels of 15 hazardous metals.

Total concentrations of the selected metals (Al, As, B, Be, Bi, Co, Fe, Li, Mo, Se, Rb, Sr, Ti, Tl and V) were determined. Standard analytical methods were used to measure soil physical and chemical properties. Total content of the twelve heavy metals, in soil samples, were extracted by microwave acid digestion and determined by ICP-OES. In the same zones, 32 pharmaceuticals were also studied. soil samples were extracted by pressurized liquid extraction (SPE). and determined by liquid-chromatography tandem mass spectrometry (LC-MS/MS).

Maximum average values were determined for Ti, Sr and Rb with 466.36, 263.16 and 63.62 mg/kg, respectively. Highest values for B, Li and Tl were 76.05, 70.91 and 56.37 mg/kg, respectively. The Northern part of the Albufera lake, devoted to rice farming, concentrated the highest values of almost all the selected elements. From the 32 studied pharmaceuticals, 29 were detected being the most frequents Bisphenol A, Caffeine and Tramadol. Maximum values were observed for Alprazolam (67.28 ng/g), Ibuprofen (76.11 ng/g) and Lorazepam (62.02 ng/g).

The interactions between metals and pharmaceuticals, and from both with soil characteristics and the influence of environmental factors were also studied.

More research is needed to stablish their toxic levels and effects, or even their average concentrations in soils of these elements, very scarcely studied in the majority of them.

Acknowledgements

This work has been supported by the Generalitat Valenciana (Regional Autonomous Government) through the project CIPROM/2021/032.

How to cite: Andreu, V., Gimeno-Garcia, E., Sadutto, D., and Picó, Y.: Possible interactions of hazardous elements with pharmaceuticals in soils of a Mediterranean wetland (L’Albufera, Valencia, Spain), EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7763, https://doi.org/10.5194/egusphere-egu24-7763, 2024.