Low Organic Carbon Research Articles

Impact of gas adsorption of nitrogen, argon, methane, and CO2 on gas permeability in nanoporous rocks

Gas adsorption on the surface of nanoporous rocks is an important process that occurs in many applied scenarios such as shale gas production or CO2 enhanced gas recovery or storage. While there are few theoretical considerations on the effect of gas adsorption on permeability, a systematic laboratory investigation of the impact of gas adsorption on gas flow and permeability is still lacking. In this paper, permeability of four adsorptive gases, i.e., nitrogen, argon, methane, and carbon dioxide, was measured, along with helium permeability, for two nanoporous rock samples that have high and low total organic carbon (TOC) content, respectively. The measurements were conducted at a range of pore pressures from 150 to 1500 psi (1.03–10.34 MPa). Gas adsorption isotherms were also measured at the same conditions. A mathematical model that considers adsorption with specific boundary conditions for the experimental setup was used for data analysis. The results show that gas adsorption causes larger drop in pressure decay and greater retardation in pressure equilibrium. However, the reduction of permeability relative to helium (25%–46%) is similar for gases with different levels of adsorption, indicating the occurrence of single-layer adsorption for these gases. Comparison between the two samples further supports the concept of single-layer adsorption and signifies the impact of pore size on the permeability reduction due to adsorption. These new findings deepen the fundamental understanding and provide important clarification on the effect of gas adsorption on gas flow and permeability in nanoporous rocks.

Field versus laboratory measurements of PFAS sorption by soils and sediments

Sorption by soils and sediments is an important process that influences the distribution, transport, and fate of per and polyfluoroalkyl substances (PFAS) in the environment. Many laboratory studies have been conducted to quantify magnitudes of PFAS sorption as a function of the properties of the PFAS, solutions, and porous media. A critical question is how representative are laboratory-measured sorption magnitudes for field applications. To address this question, log Koc data were compiled from the literature for a range of PFAS of different chain lengths and functional groups. The aggregated field-based data consisted of two types, in-situ measurements comprising paired soil/sediment and water samples and ex-situ measurements obtained from laboratory desorption experiments employing field-contaminated media. These two sets of field-based measurements were compared to a comprehensive data set of standard laboratory batch-type measurements. The compiled data sets represent an extremely wide range of soil and sediment properties. One important novel outcome is the observation that the enhanced sorption of short-chain PFAS observed in several prior laboratory studies is also observed for the field data. This differential enhanced sorption should be accounted for in site investigations and modeling studies. Another relevant outcome is the observation of consistency between measurements obtained with standard batch adsorption experiments and those from desorption studies employing either field-contaminated or artificially-contaminated media. The mean log Koc values determined for the in-situ measured field data were generally larger than the mean laboratory-determined values, particularly for the short-chain PFAS. Notably, however, values for subsets of the laboratory data representing measurements for lower aqueous concentrations or for soils with low organic-carbon contents (<1 %) compared well to the in-situ field data. Measurements compiled for anionic-polyfluoroalkyl, neutral, and cationic PFAS compared well to those for PFCAs and PFSAs. Overall, the results indicate that the laboratory measurements of PFAS sorption were generally representative of the field-derived magnitudes when compared on a consistent basis.

Revealing the optimal strategy for tree plantations on controlling soil erosion in China: A meta-analysis

Tree plantation has increased globally, driven by a desire to supply multiple ecosystem services including soil erosion control. However, how to plant trees can more effectively mitigate soil erosion still lacks systematic investigation. Therefore, we conducted a meta-analysis consisting of 412 paired observations from 80 studies to rigorously compare the effects of tree plantations on soil erosion control across different plantation approaches in China. The results showed that plantation age and ground cover type were the primary factors influencing the efficiency of tree plantations on runoff and sediment reduction. Mature plantations (>20 years) showed more efficiency in runoff (80.9 %) and sediment (97.2 %) reduction than young plantations (<10 years). The benefit of tree plantations with grass cover on runoff reduction was 70 %, while the capacity of plantations without ground cover was not significant. In addition, tree plantations in areas with steep slope, low mean annual precipitation, high soil sand content, and low soil organic carbon had better benefits on soil erosion control. Loess Plateau and Karst areas suffer the most severe water erosion in China, with distinct environmental conditions. This paper further revealed the targeted plantation strategy for these two regions: tree plantations in Karst areas should focus on the lithophyticity and drought tolerance of tree species, in the Loess Plateau should consider the trade-off between water consumption and soil erosion control.

Shift of bacterial and fungal communities upon soil amelioration is driven by carbon degradability of organic amendments

The structural response of bacterial and fungal soil communities to four carbon-rich organic amendments of increasing recalcitrance was investigated. Wheat straw, green compost, a mixed product based on biogas residues, and a fermented biochar were applied to a sandy agricultural soil of low organic carbon content. After laboratory incubation for 6 months, the community structure was investigated via DNA sequencing. All amendments caused changes in the communities of bacteria and fungi, but to different extents, with the communities exposed to more recalcitrant amendments showing the least variation compared to the non-amended soil. Changes in species composition as well as their relative abundances were observed. While the straw had a pronounced effect on bacteria (e.g., the highest number of indicator species), effects of the composted, fermented, or pyrolyzed materials were minor. Hierarchical clustering showed that the fungal communities were more different from each other than the bacterial ones with the straw-soil being most different and the biochar-soil least different from the non-amended soil. While the abundant fungal species in biochar-soil and non-amended soil were very alike, especially rare fungal species shifted upon addition of biochar. An indicator species analysis identified specific taxonomic groups which were triggered by the different organic materials. We conclude that bacterial and fungal communities strongly change upon input of degradable carbon (straw), while fungi in particular respond to the application of processed organic materials. With this study, we report the consequences of applying organic materials for the microbial community in one soil. We provide these data for meta-analyses that are required to unravel all relevant interactions across different soils, organic materials, and time. This will allow to better understand and predict the effects of organic soil amelioration measures on soil microorganisms.

Natural and anthropogenically driven change of organic carbon burial rate in two alpine lakes from the southeastern margin of the Tibetan Plateau

The rate of organic carbon (OC) burial in lakes depends considerably on natural and anthropogenic factors. Delineating how and to what extent potential drivers shape a lake’s OC burial rate is crucial for anticipating OC sequestration under future environmental change scenarios. Alpine lakes provide valuable opportunities for studying the influence of climate warming and atmospheric nitrogen (N) deposition on OC burial in lakes, owing to the lack of human activities in their catchments; however, this aspect has not been sufficiently documented. Here, the OC burial rate was reconstructed in two alpine lakes (Heihai and Jiren) from the southeastern margin of the Tibetan Plateau over the past ∼ 160 years, and the associated drivers were identified by resolving the temporal trends in organic matter (OM) input from specific sources to lake sediments via paleolimnological methods. The results demonstrated a consistently low OC burial rate (6.21–10.86 g m−2 yr−1) in Lake Heihai. The low hydrogen index (HI), moderate Paq, and high long-chain n-alkane flux revealed that submerged macrophytes and terrestrial plants are major contributors to the sequestrated OC. The notable decrease in the OC burial rate after 1980 was hypothesized to be caused by regional climate warming during this period because a greater export of terrestrial materials under such a climate can inhibit light penetration, diminishing submerged macrophyte productivity and OM input. In contrast, the synchronous input of higher amounts of terrestrial plant OM was largely degraded owing to the increased water temperature and the intensification of water column stratification. In Lake Jiren, a notably high OC burial rate (13.82–46.75g m−2 yr−1) was observed. The high HI, Paq, and short-chain n-alkane flux showed that phytoplankton and submerged macrophytes were the major contributors to the sequestrated OC. The two-phase increase in the OC burial rate in this lake, including a slow increase after 1947 and a rapid increase after 1983, might have resulted from strengthening aquatic primary productivity and OM input, driven by anthropogenic intensification of nutrient emissions, especially reactive N, from highly urbanized areas and the subsequent long-term atmospheric transport and deposition of these materials over the lake basin. A comparative analysis of the results between the two lakes suggested that atmospheric N deposition has a stronger influence on the OC burial than climate warming. These drivers affect the OC burial rate by altering aquatic productivity rather than the terrestrial OM input. This study provides a basic for predicting future OC burial scenarios in warmer climates with more intense anthropogenic N emissions.

Assessment of Different Nutrient Combination on the Performance of Maize (Zea mays L) in North Indian Plains

A field experiment was conducted during the kharif season of 2023 at the Agriculture Research Farm, Graphic Era Hill University, Uttarakhand. Surface soil (0-15 cm) of the experiment field was sandy loam in texture, low organic carbon (0.39%), medium in available nitrogen (157 kg h-1), medium in available phosphorus (15.5 kg ha-1) and medium in available potassium (112.6 kg ha-1) with neutral soil reaction (pH 7.4). The experiment consisted of eleven treatments viz., 100% NPK (T1), 100% N (T2), 100% P (T3), 100% K (T4), 100% NP (T5), 100% NK (T6), 100% PK (T7), 100% NPK + VC 5 t ha -1 (T8), 100% + Azotobactor (T9), 100% + VC 5 t ha -1 + Azotobactor (T10), Control (T11). Each treatment was replicated thrice and constituted total of 33 plots. The field experiment was laid out in a randomized block design (RBD). The variety used for the field experiment was K-55. The results of the field experiment reported that the effect of different treatments was significant on growth and productivity of maize. Significantly higher emergence count m-2 (9 m-2) of maize was obtained with the application of 100% NPK + VC @ 5t ha-1 + Azotobacter (T10). Maximum plant height (102.07 cm, 155.02 cm and 225.87 cm) was observed under treatment 100% NPK + VC @ 5t ha-1 + Azotobacter (T10) at 30, 45 and 60 days of sowing, respectively. It also produced highest dry matter m-2 (556.56 g, 1023.20 g, and 2062.00 g, respectively at 30 DAS, 45 DAS and 60 DAS). Application of vermicompost along with Azotobacter and chemical fertilizer produced maximum number of leaves per plant (4.05, 8.87 and 14.20 at 30 DAS, 45 DAS and 60 DAS, respectively). Application of 100% NPK + VC @ 5t ha-1 + Azotobacter (T10) resulted in significant improvement in yield attributes and yield of maize compared to other treatments. The maximum grain yield (59.93 q ha-1) and straw yield (69.90q ha-1) was produced under 100% NPK + VC @ 5t ha-1 + Azotobacter (T10). Moreover, adoption of different nutrient combinations resulted in improving the economic status of the farmer. Significantly higher B: C ratio of 1.90 was recorded for 100% NPK + VC @ 5t ha -1 + Azotobacter (T10) and it was 14.45 % higher than that for 100 % NPK (T1). Hence, it is concluded that application of 100% NPK + VC 5 t ha -1 + Azotobacter exhibited higher growth and yield along with B: C ratio.

Effects of temperature, relative humidity and soil organic carbon content on soil-air partitioning coefficients of volatile PFAS

Soil-air partitioning coefficient (KSA) values are often used to assess the environmental fate of organic contaminants in soil. Till now, sufficient KSA values have not yet been measured for many compounds of interest, including some emerging pollutants such as volatile PFAS. Moreover, the effects of environmental factors such as temperature, relative humidity and soil organic carbon content on KSA of volatile PFAS are also unclear. In this study, the KSA values of target volatile PFAS were measured under various temperature (20–40 °C), relative humidity (30–100 %) and soil organic carbon content (2.1 %–8.0 %) using a modified solid-phase fugacity meter. The results showed that higher temperatures, higher relative humidity and lower organic carbon content in soil may accelerate the diffusion of target volatile PFAS. Furthermore, the KSA measurements were used to derive a multiple linear regression model to depict the relationship between logKSA and temperature, relative humidity, soil organic carbon content and PFAS-specific logKOA. When compared with the predictions obtained from semi-empirical model, we argued that the multiple linear regression model is more robust and easier to implement for target volatile PFAS or other emerging volatile PFAS than the semi-empirical approach to help depict the diffusion process at target volatile PFAS contaminated sites.

Transect approach for assessing major and trace elemental contamination in agricultural soils of the palamaner division, chittoor district, andhra pradesh, india.

Three soil transects located in the granitic regions of Palamaner mandal, Andhra Pradesh, India, were examined to assess the pollution levels of both primary and secondary metals (Si, Al, Fe, Ca, Mg, Na, K, Cu, Mn, P, and Zn) and to ascertain the degree of soil pollution in agricultural areas. The soils along these transects are slightly acid to neutral, with dark brown to red rubified argillic clay-rich B horizons alongside a moderate cation exchange capacity. The A horizon soils display low organic carbon levels with a moderate variability and contain over 70% SiO2, exhibiting low variability due to limited leaching in a semiarid climate. The findings suggest that iron (Fe) and manganese (Mn) oxides play a role in reducing contamination levels through oxidation and precipitation processes. Furthermore, the soils show low to moderate cation exchange capacity, which restricts the retention of absorbed heavy metals, thus lessening their negative impacts. A two-way ANOVA revealed significant differences in CEC, organic carbon, and total zinc content across different horizons and landscape positions. Si, Al, and Cu had small increases and negative geoaccumulation indices in all soil profiles, suggesting no pollution. However, the Nemerow and mean contamination degree over 6 point to slight to moderate pollution. The analysis identified three distinct clusters with significant variations in contamination factors for SiO2 and Cu. Five principal components were determined, explaining 76% of the total variance, primarily derived from geogenic sources and remaining within acceptable limits. This research on soil transects in granitic regions contributes to a better understanding of the distribution, movement, and concentration of elemental oxides based on slope position, which is essential for pollution assessment and soil quality enhancement.

Organic Carbon Reaction Kinetics in Bioturbated Sediments

AbstractMost organic carbon delivered to the seafloor is degraded within the bioturbated layer. Theory and empirical evidence have shown that organic carbon reactivity relates to the age of a particle. However, due to particle mixing, the age‐depth linear relation induced by sediment accretion is obfuscated. Here we combine a Lagrangian particle tracking model that resolves the age distribution of particles in the bioturbated zone and couple it to age‐dependent organic carbon degradation. Depth profiles for organic carbon concentration, reactivity and degradation rate are presented for sediments receiving low and high reactivity organic carbon in coastal, continental slope and deep‐sea environments. Our results show that a simple first‐order kinetics model suffices for well‐mixed sediments and systems receiving pre‐processed materials. A reactive continuum approach is needed for poorly mixed sediments receiving highly reactive organic carbon and for sediments below the bioturbated layer.

Behavioral and toxicological impacts of bio-derived oils in aqueous spills

There is an increasing global demand for, and transportation of, goods classified as Hazardous and Noxious Substances (HNS), including bio-derived oils and chemicals. With the increasing variety of bio-feedstocks and the development of processing technologies, the physical and chemical properties of commercially available and transported bio-derived oils vary significantly. The objective of this work was to analyze and compare the physical and chemical characteristics, behaviour, and risks of several bio-derived oils (four vegetable oils, one biodiesel, and two pyrolysis oils) and one petrol diesel when spilled into both fresh and salt water system. The laboratory results indicated that the vegetable oils and biodiesel remained buoyant and resulted in low total organic carbon (TOC) in water when spilled, similar behaviour to petrol diesel. However, the two pyrolysis oils exhibited remarkably different behaviours. The two oils sunk directly in the water and then rapidly dissolved the organic components into the water when mixed. This resulted in a high TOC (100 times higher than other types of oil) and an altered water chemistry, leaving a large portion of water-insoluble portion (35.0 wt% of pyrolysis oils) remaining at the water bottom. Initial Microtox findings indicated that water samples contaminated with pyrolysis oils and biodiesel (similar to petrol diesel) exhibited increased aqueous toxicity towards Vibrio fischeri. Further biological tests are required to understand their ecological risks. This work provides insights to the challenges and knowledge gaps on the fate, behaviour and risk of emerging bio-derived oils in water, while supporting HNS emergency response and remediation measures.

Devastation of the cerrado of mato grosso do sul and the advance of arenization in the pardo river watershed

Despite the significant biodiversity in the Cerrado, the process of occupation, subsequent economic cycles, and intensification of agriculture in a predatory manner have caused profound alterations in this biome. This study analyzed changes in land use and land cover in the Cerrado of Mato Grosso do Sul between 1985 and 2022 by mapping and also investigating the formation and dynamics of sand dunes in the Bauru sedimentary basin, focusing on the Pardo River watershed. MapBiomas Network data, collection 8, were used for land use and land cover analysis. Arenization foci cartography was conducted using brightness index 2 based on Sentinel-2 satellite images in Sentinel Application Platform software. The historical analysis of land use and cover in the Cerrado of Mato Grosso do Sul revealed a rapid transformation of the landscape, with a drastic reduction of native vegetation and an intensification of large-scale monocultures. Between 1985 and 2022, the Cerrado of Mato Grosso Sul lost 4.6 million hectares of native vegetation (forest formations, savannahs, grasslands, and wetlands), representing 24.54% of this territory. Recent changes in land use include pasture-soybean and pasture-eucalyptus. In the Pardo River watershed, arenization foci cover an area of 17,834.34 hectares, with varying dimensions ranging from less than 1 hectare to 376.41 hectares. The arenization process occurs in different slope compartments, such as the base, slope, and interfluves. The physical and chemical characteristics of Quartzipsamments, such as low organic carbon content in soil, are associated with high rates of surface exposure and weakened load-dependent structures, leading to degradation. Arenization occurs where natural vegetation has been suppressed and soil has been depleted by poorly managed production processes.

A 14,000‐Year Sediment Record of Mercury Accumulation and Isotopic Signatures From Lake Malaya Chabyda (Siberia)

AbstractEurasian permafrost soils contain large amounts of organic carbon (OC) and mercury (Hg), sequestered by vegetation during past and present interglacial periods. Lake sediment archives may help understand past OC and Hg dynamics and how they interact with climate‐related variables. We investigated Hg accumulation, OC dynamics, and Hg and OC stable isotopes in a 14,000‐year sediment record from Lake Malaya Chabyda (Central Yakutia, Russia). Sediment Hg was correlated to OC (p value &lt; 0.01), with lower OC and Hg accumulation rates (OCAR, HgAR) during the cold Younger Dryas (YD, 12,900–11,700 cal BP), when the lake level was low. Elevated sediment Δ200Hg (0.05‰ ± 0.11‰), representing dominant HgII deposition, and low δ13C, indicates low lake primary productivity during the YD. During the early Holocene, Δ200Hg and Δ199Hg decreased, while δ13C, δ202Hg, OCAR, and HgAR increased, suggesting enhanced algal primary productivity in deeper, more turbid waters. From 4,100 cal BP to present, Hg/OC ratios and HgAR increased at constant OCAR, indicating an additional Hg source to the lake. Analysis of Hg isotopes suggests direct Hg0 uptake into lake waters, potentially driven by primary production and efficient Hg burial. Our observations suggest that the gradual climate warming since the Last Glacial Termination and into the early Holocene led to enhanced OC and Hg burial in northern lakes and watersheds. Late Holocene enhanced Hg burial, but not OC, is possibly related to a renewed increase in lake primary productivity. Continued global warming may lead to further Hg sequestration in northern aquatic ecosystems.

Biostability assessment of ultrapure water piping materials in the semiconductor industry and their susceptibility to Ralstonia growth

The pipes used for ultrapure water (UPW) distribution are constructed using high-quality materials to ensure purity. However, there remains a risk of contamination based on the pipe type. This study is the first to comprehensively evaluate the biological implications of various UPW pipe materials used in the semiconductor industry. The results showed that Polyvinylidene fluoride (PVDF) exhibited lower organic carbon leaching (0.08 mg/L) and a reduced biomass formation potential (BFP) (approximately 5 × 105 cells/cm2) compared to chlorinated polyvinyl chloride (CPVC) pipes. In particular, Ralstonia, an oligotrophic bacterium commonly found in UPW systems, formed a significant biofilm on pipe surfaces, notably in stainless steel (SUS) and CPVC pipes. Furthermore, particle contamination, a critical concern in semiconductor manufacturing, was investigated, focusing on potential contamination sources generated by pipe leaching and the presence of bacteria. The bacterial composition of the selected UPW was investigated, revealing Herbaspirillum, a nitrogen-fixing bacterium, as the dominant species, account for 66.15 %. Notably, the composition of the feedwater was different from that of the UPW. This study also highlights the limitations of culture-based methods, particularly in detecting bacteria under oligotrophic conditions, which are often unculturable. Flow cytometry (FCM) shows promise for the quick detection of bacterial contamination by providing total cell counts. Moreover, cytometric fingerprinting analysis revealed phenotypic differences between the communities. Nevertheless, further development of a simplified and widely applicable cell counting protocol is required for its effective integration into UPW production.

Carbonaceous aerosol emissions from secondary lighting sources: Emission factors and optical properties

India is shifting towards cleaner residential fuels, but this transition does not fully address household lighting challenges. Power disruptions, especially in rural areas, lead to the use of secondary lighting sources such as kerosene lamps, edible oil lamps, and candles. Our previous work identified kerosene wick and hurricane lamps as major secondary lighting sources in Indian households. This study presents the emission factors (EF) and optical properties of carbonaceous aerosols from five major secondary lighting devices in India, measured using a laboratory extractor hood system. Dominant secondary lighting devices, such as simple wick lamps (61.4 ± 9.8 g kg⁻1) and hurricane lamps (17.2 ± 4.8 g kg⁻1), exhibit higher elemental carbon (EC) EFs than typical residential biomass burning. Sesame oil lamps, primarily used in India during the Diwali festival, also have significant EC emission potential, with an EC EF of 71.6 ± 16.9 g kg⁻1. The low absorption Angstrom exponent (AAE) of ∼1 at near-UV wavelengths indicates a dominance of black carbon (BC) and negligible brown carbon absorption, corroborated by very low organic carbon concentrations. India-wide EC emissions (12.5 Gg year⁻1) from residential kerosene lighting show a higher (∼50%) contribution from eastern India. Additionally, the use of oil lamps during the Diwali festival could emit ∼3 Gg of EC in two days, with a potential reduction of ∼90% if wax-based lamps replace oil lamps. These measured EFs, aerosol optical properties, and estimated emissions will help future studies derive more accurate climate and health impacts from these otherwise overlooked lighting devices.

Drought impairs detritivore feeding activity more strongly in northern than in southern European latitudes

Soil detritivores play key roles in decomposition processes closely related to ecosystem services. Drought and soil organic carbon depletion due to agricultural management are detrimental to soil biodiversity, but their interactive effects on soil biota and associated processes have not been thoroughly investigated. In 2018, we used rain-out shelters to experimentally induce drought in wheat fields of contrasting levels of organic carbon in Sweden, Germany and Spain. That year Europe experienced a climatic dipole, with exceptionally severe droughts in northern latitudes. We assessed the feeding activity of soil detritivores by bait-lamina tests, and measured several abiotic and biotic soil parameters. In the peak of the dipole drought (summer) southern fields had the driest soils. Nonetheless, detritivore feeding activity responded to the experimental drought by shifting to deeper soil layers there. Low soil organic carbon (SOC) levels exacerbated the latter effect. However, in this same period, feeding activity in northern and central Europe was two orders of magnitude lower than in the south, and failed to respond to either the experimental treatment and/or SOC levels. Using mixed-effects longitudinal random forests, we detected various candidate drivers of detritivore feeding activity: soil moisture, phosphorus content, bacteria and nematodes. Different bacterial taxa were associated to detritivory in each country, but their potential influence was pervasive. Thus, our results suggest that drought had adverse effects on detritivore feeding, which were exacerbated northwards due to the climatic dipole. Increased SOC levels mitigated drought effects only in southern soils. Regional adaptation of soil biota to aridity could explain the response of detritivores in southern Europe to drought. Machine learning algorithms arise as useful tools for exploring potential drivers relating biodiversity to soil processes. Overall, future research on the effects of drought on soil biodiversity and processes will be key for tackling climate change impacts in terrestrial ecosystems.

Effects of farmyard manure and chemical fertilizer application rates on soil biology, cotton and fiber yield

Organic and inorganic fertilizers have significant effect on plant physiology, yield per unit area, available plant nutrient contents and extracellular enzyme activities of soils. This study was carried out in field conditions in arid and semi-arid regions between 2020-2021 years, May 01. The effects of farmyard manure (FM) (20, 40, 60 Mg ha-1) and chemical (CF) (350 kg urea ha-1, 100, 200, 300 kg DAP ha-1) fertilizers applied at different rates on plant nutrient (N, P, K, Ca, Mg, Fe, Cu, Zn and Mn) contents, SPAD value and NDVI of cotton plants, seed cotton yield and soil enzymes (urease, catalase, dehydrogenase, alkaline phosphatase) were investigated. The results showed that FM applications significantly (p&lt;0.01) increased the plant macro and micronutrients compared to CF applications, except for N (200 + 150 kg urea ha-1), Zn and Cu (300 kg DAP + 200 + 150 kg urea ha-1) in the 2021 cotton growing season. Mineralization of FM is slow under natural conditions; therefore, the use of FM alone is not sufficient to meet the nutrient needs of high yielding varieties. Urease and dehydrogenase activities increased significantly in FM treated soils compared to CF, while no significant (p&lt;0.01) increase was recorded in alkaline phosphatase and catalase activities. Farmyard manure is a useful management practice for increasing soil biological activity. Physiological parameters of NDVI, SPAD and seed cotton yield significantly increased in FM treated soils compared to CF applications. The increase in cotton yield was 29.15%, in NDVI value was 22.38% and in SPAD value was 121.7%. The main issues with cotton in the area are the low organic carbon content of the soils, high clay content, arid and semi-arid soils, and their detrimental impact on the uptake of particular nutrients (N, P and B).

Soil Fertility Status of Paddy (Oryza Sativa L.) Growing Soils of Different Agro-climatic Zones, Telangana, India

The main occupation of Telangana State, India, is agriculture. Achieving food security requires intelligent management to increase land use productivity and production per unit area because of the expanding population and decreasing amount of agricultural land per capita. In this sense, assessing the productivity and fertility of the soil is a necessary step toward sustainable agricultural development. In the current study, paddy grown different soils in the districts of Telangana State were assessed for soil fertility using random sampling approach. This study was conducted to analyze the fertility characteristics of paddy cultivated soils in different districts of Telangana State. Collected 275 soil samples at 0-15cm depth under paddy crop grown during 2018-19 and 2019-20. The samples were found to be slightly acidic to alkaline in nature and low amount of soil organic matter. Soil nutrients such as available nitrogen (N), phosphorous (P) and potassium (K) ranged from 50-401 kg ha-1, 17-147 kg ha-1 and 60-842 kg ha-1 in red soil, 63-314 kg ha-1, 33-126 kg ha-1 and 95-460 kg ha-1 in black soil and 73-312 kg ha-1, 25-158 kg ha-1 and 153-458 kg ha-1 in alluvial soil, respectively. The paddy cultivated soil survey results conclusively indicate that the soil samples reveals normal soil reaction, electrical conductivity and low organic carbon (0.48% average) and widespread low nitrogen levels (91% of samples). Conversely, phosphorus availability is high (82% of samples) with an average content of 82 kg P2O5 ha-1, and potassium levels are notably elevated (57%).

Vineyard cover crop management strategies and their effect on soil properties across Europe

AbstractVineyard soils are often of inherently poor quality with low organic carbon content. Management can improve soil properties and thus soil fertility. In European wine‐growing regions, a broad range of inter‐row management strategies evolved based on specific local site conditions and the varying effects of management intensities on soil, water balance, yield and grape quality. Accordingly, there is a need to investigate the effects of locally common cover crop management strategies and tillage intensity on soil organic carbon content and soil physical parameters. In this study, we investigated the impact of the most common inter‐row management practices in Austria, France, Romania and Spain. In all countries, we compared paired sites. Each site with cover crops and inter‐row management of low intensity was compared with one site with (temporarily) bare soil and high management intensity. All studied sites with cover crops and low management intensity, except those in Spain, had higher organic carbon contents than the paired more intensively managed vineyards. However, the highly water‐limited Spanish vineyards with temporary cover crops had lower organic carbon contents than the paired sites with bare soil. Sites with more organic carbon had better results for bulk density, percolation stability (PS), hydraulic conductivity and available soil water, with soil hydraulic parameters being less pronounced than others. Country comparison of inter‐row weed control systems showed that PS was particularly low in sampled vineyards in Romania and Spain, where weed control is based on intensive mechanical tillage. Alternating management systems with tillage every second inter‐row showed a decrease in soil structure compared with permanent green cover. Thus, inter‐row management with cover crops and reduced tillage increases soil organic carbon content and improves soil structure compared with bare soil management. If local constraints, such as water scarcity, do not allow year‐round planting, alternating inter‐row management with several years of alternating periods may be an option to mitigate those adverse effects. However, negative impact on the soil structure occurs with the very first tillage operation, whereas negative effects on the carbon balance only appear after long‐term use of tillage.

Hydrocarbons, Hydrogen, and Organic Acids Generation by Ball Milling and Batch Incubation of Sedimentary Rocks

Pulverized rock samples are widely used in laboratory experiments, e.g., to assess microbial or abiotic processes in batch incubation tests. However, it is unclear if ball-milled samples accurately reflect in-situ conditions and if observed processes are affected by by-products artificially generated during the sample preparation procedure. As such, this study examined the effects of dry ball milling on the release of gases, which include C1-C4 hydrocarbons, carbon dioxide (CO2), hydrogen (H2), and low molecular weight organic acids (LMWOAs) from different sedimentary rocks. The experiments involved pulverization using a gas-tight zirconium oxide planetary ball mill followed by wet and dry batch incubation and thermal desorption up to 200 o C. During milling, all sedimentary rocks, except a low organic carbon sandstone sample, yielded methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), H2, CO2, and unsaturated hydrocarbons, e.g., ethene (C2H4). Sandstones only yielded H2, CH4, and CO2. Stable carbon isotope signatures of these products are similar to thermogenic gases. The gases were also detected in subsequent wet incubation experiments (after gases from milling had been removed). Additionally, formate, acetate, and citrate, were detected in all samples except for sandstone. Pyruvate, malate, and succinate were also detected in some samples. Thermal desorption products of powdered limestone, shale, and pyrite concretion samples included organic acids, such as acetate and formate, which were higher in milled samples than in crushed particles (∼1 mm). The original geological thermal maturity of the studied sedimentary rock samples was low (below “oil window”) and, thus, considerably below “gas window”, suggesting that most of the detected gases were generated during ball milling. H2 generated during ball milling may be derived from the reduction of water from fluid inclusion or phyllosilicates, involving the formation of reactive mineral surfaces or radicals. Notably, the concentrations of gaseous hydrocarbons derived from milling are relatively high and comparable to “wet” gases. At the same time, these data indicate that substantial amounts of gases and LWMOAs might be artificially generated during laboratory batch experiments with milled samples. Hence, ball milled rock samples must be used with caution if assessing (bio-)geochemical processes for natural environments.

Partitioning denitrification pathways in N2O emissions from re-flooded dry paddy soils

In flooded paddy fields, peak greenhouse gas nitrous oxide (N2O) emission after rewetting the dry soils is widely recognised. However, the relative contribution of biotic and abiotic factors to this emission remains uncertain. In this study, we used the isotope technique (δ18O and δ15NSP) and molecular-based microbial analysis in an anoxic incubation experiment to evaluate the contributions of bacterial, fungal, and chemical denitrification to N2O emissions. We collected eight representative paddy soils across southern China for an incubation experiment. Results show that during the 10-day incubation period, the net N2O emissions were mainly produced by fungal denitrification, which accounted for 58–77% in six of the eight investigated flooded paddy soils. In contrast, bacterial denitrification contributed 6–15% of the net N2O emissions. Moreover, around 11–35% of the total N2O emissions were derived from chemical denitrification in all soil types. Variation partitioning analysis (VPA) and principal component analysis (PCA) demonstrated that initial soil organic carbon (OC) concentrations were the primary regulator of N2O source patterns. Soils with relatively lower OC concentration (7–15 mg g−1) tend to be dominated by fungal denitrification, which accounted for the net N2O production at the end of the incubation period. Overall, these findings highlight the dominance of the fungal denitrification pathway for N2O production in flooded paddy soils, which predominates in soils with relatively lower OC content. This suggests that fungal contribution should be considered when optimizing agricultural management system timing to control N2O emissions in flooded paddy soil ecosystems, and for the relevant establishment of predictive numerical models in the future.