Organic Matter Content Research Articles

Ecological risk, source apportionment, and influencing factors of heavy metals in soil in a typical lead-zinc mining watershed, Guangxi, China

Soil contamination by heavy metals (HMs) leads to significant decreases in soil ecosystem quality, seriously threatening human survival and development. Studies on soil HMs have focused on the sources, distributions, and influencing factors. However, soil HM migration and speciation, which indirectly affect HM distributions and their ecological risks, have often been overlooked. In this study, we investigated the links between the sources, distributions, and influencing factors of soil HMs, as well as their ecological risks at several levels, by analyzing soil samples collected from a Pb-Zn mining area. Soil column experiments were also performed to assess Pb leaching in the soil. The results indicate that soil HMs accumulated in front of the mountain river outlets, at the entrance of the underground river, and at soil depths of 0–40cm. Cd and Pb were the main contributors to the high ecological risk in the soil, and As and Cr were the main contributors to cancer risk. The source analysis indicates that mining and smelting activities were the main sources of total soil HMs (32.55%), as well as the main sources of Sb (83.43%), Pb (68.65%), and Cu (45.37%). Mining activity and continuous riverine transport were the main sources of Cd (69.93%) and Zn (52.38%). These anthropogenic sources have major impacts on the ecological environment in the study area. Factors such as pH, clay and silt contents, soil organic matter content, and cation exchange capacity influenced the distributions and total amounts of Cu, Mn, Zn, and Pb species.

Stearate from Steel Wire Drawing Processes as a Resource

STAR (Stearato dai processi di Trafilatura del filo di Acciaio come Risorsa) project, funded by the Italian Ministry of the Environment, has the ambition of redesigning the use and life cycle of waste stearates from the steel wire drawing industry, promoting the circular life of such materials. Waste stearate is having a strong impact on the economic and environmental sustainability of the steel wire production processes, adding up to the increasing pressure that industry has been facing in the last years: the pandemic crisis, the raw material price increase, the commercial restrictions related to the Ukraine and other regional conflicts.The short-term goal of the project is to develop a technology to be applied on a local scale and the long-term one is expanding it internationally. The benefits are both environmental, due to the reduction of waste and related impact on the environment, and economic, due to stearate valorization.First, stearate waste from wire drawing process were characterized in order to valorize them in the production of new materials or as an energy source.Samples of stearate waste were provided by wire drawing industries and the analyses showed that the humidity content was always low (0.1 – 5 %), while the volatile solids (VS) content varied from 2 to 70%, covering a very wide range and thus indicating a variable organic matter content. The mean higher heating value was 26 MJ/kg and the Chemical Oxygen Demand (COD) 500 mg O2/g and correlated well with VS. pH was strongly basic (>11).Anaerobic digestion can surely have an important role in valorization, as it allows to recover energy and to produce a stabilized digestate for which a further use can be studied, according to its properties. Preliminary BMP tests (BMP = Biomethane Potential) determined a biomethane production in the range 500-900 L/kgVS, much higher than the production from animal waste (around 400 L/kgVS). The toxicity of the digestate was assessed by Microtox® assay and was negligible. This finding supports the hypothesis that recalcitrant compounds, which do not undergo degradation in anaerobic conditions, are not toxic.

Effect of Land Use Change on Molecular Composition and Concentration of Organic Matter in an Oxisol.

Land use change from native vegetation to cropping can significantly affect the quantity and quality of soil organic matter (SOM). However, it remains unclear how the chemical composition of SOM is affected by such changes. This study employed a sequential chemical extraction to partition SOM from an Oxisol into several distinct fractions: water-soluble fractions (ultrapure water (W)), organometal complexes (sodium pyrophosphate (PP)), short-range ordered (SRO) oxides (hydroxylamine-HCl (HH)), and well-crystalline oxides (dithionite-HCl (DH)). Coupled with Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR-MS), the impact of land use change on the molecular composition of different OM fractions was investigated. Greater amounts of OM were observed in the PP and HH fractions compared to other fractions, highlighting their importance in SOM stabilization. The composition of different OM fractions varied based on extracted phases, with lignin-like and tannin-like compounds being prevalent in the PP and HH fractions, while aliphatic-like compounds dominated in the DH fraction. Despite changes in the concentration of each OM fraction from native vegetation to cropping, there was little influence of land use change on the molecular composition of OM associated with different mineral phases. No significant selective loss or preservation of organic carbon compounds was observed, indicating the composition of SOM remained unchanged.

Exploring Catalase Activity as A Biological Indicator in Degraded Soils

This study examines the relationship between catalase activity in degraded soils and soil properties, and addresses its potential as an indicator of soil health and productivity. Catalase, a key enzyme reflecting microbial activity and soil aeration, has been analyzed in 30 soil samples collected from the disturbed surface layer (0-15 cm depth) of erosion-prone areas characterized by rubble accumulation on hill slopes and soil compaction in foot slopes. The soil in the study area is classified as Typic Xerortent. Catalase enzyme activity in the soil samples varied between 10.4 and 48 µl O2 g-1 dry soil. In addition to catalase, the physicochemical properties of the soil were also assessed, including pH, electrical conductivity, organic matter content, and texture. Nutrient contents, including nitrogen (0.046-0.239 g N 100 g-1), phosphorus (1.77-20.05 µg P g-1), and potassium (0.01-3.31 meq K 100 g-1), were also measured. A positive correlation was observed between catalase activity and potassium and phosphorus levels, but the relationship with nitrogen was statistically insignificant. These findings suggest that catalase activity can serve as a biological indicator for the early detection of degradation in soils at risk of erosion. The study provides valuable insights into the impact of erosion on soil biochemistry and highlights the role of catalase in assessing soil health and guiding sustainable land management practices.

Life Cycle Assessment of Immobilised and Slurry Photocatalytic Systems for Removal of Natural Organic Matter in Water

This study investigates the environmental impacts caused by the scaling up of the photocatalytic purification of drinking water using ultraviolet light-emitting diode technology. The life cycle assessment methodology was utilised to estimate the environmental impacts of two different reactor setups commonly used in lab-scale studies: an immobilised and a suspended TiO2 catalytic system. The functional unit adopted was the treatment of 1 L of water with an initial 7.8 mg/L concentration of natural organic matter, achieving a final 1 mg/L concentration. The use of a suspended photocatalyst was found to have an environmental footprint that was 87% lower than that of the immobilised one. From the sensitivity analysis, the environmental hotspots of the treatment process were the electricity usage and immobilised catalyst production. Therefore, alternative scenarios investigating the use of a renewable electricity mix and recyclable materials were explored to enhance the environmental performance of the photocatalytic treatment process. Using a renewable electricity mix, a decrease of 55% and 15% for the suspended and immobilised catalyst, respectively, was observed. Additionally, the process of recycling the glass used to support the immobilised catalyst achieved a maximum reduction of 22% in the environmental impact from the original scenario, with 100 glass reuses appearing to provide diminishing returns on the environmental impact savings.

Crop Suggestive System through Soil Property Characterization using IoT

The emergence of Internet of Things (IoT) technology has brought about a significant transformation in multiple sectors, including agriculture, by facilitating data- driven decision-making and real-time monitoring. In this work, we present a novel Internet of Things (IoT) agricultural suggestion system that uses soil property characterization to enable accurate crop management and selection. Our technology seeks to help farmers optimize agricultural yields while minimizing resource usage and environmental impact by combining IoT sensors with modern data analytics. Our system's primary feature is the installation of Internet of Things (IoT) sensors throughout fields to continuously collect data on important soil attributes. These characteristics include salinity, pH values, temperature, moisture content, nutrient concentrations, and organic matter content. This data is wirelessly transmitted by the sensors to a cloud platform or centralized database, where it is thoroughly analyzed. One of the many difficulties facing modern agriculture is choosing crops optimally to maximize yields while minimizing environmental effect. Conventional crop selection techniques sometimes rely on manual soil testing or broad suggestions, which produces less than ideal results and inefficiencies. A novel method using the Internet of Things (IoT) is suggested to address this: a Crop Suggestive System using Soil Property Characterization (CSS-SPC). Using Internet of Things sensors, this system continuously monitors and analyzes soil parameters in real-time, giving farmers customized crop recommendations depending on the unique conditions of their property. Crop rotations, soil amendments, and irrigation schedule optimization are made possible for farmers through smooth planning and decision-making that ismade possible by integration with current farm management systems. Farmers' ongoing input on the effectiveness ofsuggested crops guarantees the system's accuracy and continued applicability

Concentration of heavy metals in soil and leaves of Conocarpus Erectus Tree: A Biomonitoring Study, Ahvaz, Iran.

Heavy metals biomonitoring was performed using the Conocarpus erectus tree in Ahvaz city. Composite leaf and soil samples were collected from 23 selected stations. The concentrations of heavy metals (Pb, Zn, Cd, Cu, Fe and Mn) in leaf and soil samples, and bioavailability of metals in soil samples were determined. Examination of soil physicochemical parameters proved neutral to slightly alkaline nature, and low organic matter content in the soil samples. The mean concentration of heavy metals in soil was: Fe > Mn > Zn > Pb > Cu. Ecological risk assessment of heavy metals was in the range of safe to low risk (RI < 150). Although the concentration of metals in the more polluted areas was higher in both leaf and soil samples, there was no significant relationship between the concentrations of metals in the leaf and soil samples. This relationship is even lower between the bioavailable component of metals in the soil and the concentration of metals in the leaves. Transfer factor values based on total contents of metals in soil samples indicated that Conocarpus erectus is mostly contaminated with Zn and Cu. The results of Accumulation factor of plant revealed that Pb, Zn, and Fe were mostly enriched in the plant by anthropogenic activities. MAI values in heavy and light traffic, and industrial areas were 11.88, 8.01 and 8.15, respectively. In general, it is evident that the Conocarpus erectus leaves accumulate heavy metals in polluted areas, so it can be used as a bioindicator of air pollution with heavy metals in regions with similar conditions.

Significant impact of urban tree biogenic emissions on air quality estimated by a bottom-up inventory and chemistry transport modeling

Abstract. Biogenic volatile organic compounds (BVOCs) are emitted by vegetation and react with other compounds to form ozone and secondary organic matter (OM). In regional air quality models, biogenic emissions are often calculated using a plant functional type approach, which depends on the land use category. However, over cities, the land use is urban, so trees and their emissions are not represented. Here, we develop a bottom-up inventory of urban tree biogenic emissions in which the location of trees and their characteristics are derived from the tree database of the Paris city combined with allometric equations. Biogenic emissions are then computed for each tree based on their leaf dry biomass, tree-species-dependent emission factors, and activity factors representing the effects of light and temperature. Emissions are integrated in WRF-CHIMERE air quality simulations performed over June–July 2022. Over Paris city, the urban tree emissions have a significant impact on OM, inducing an average increase in the OM of about 5 %, reaching 14 % locally during the heatwaves. Ozone concentrations increase by 1.0 % on average and by 2.4 % during heatwaves, with a local increase of up to 6 %. The concentration increase remains spatially localized over Paris, extending to the Paris suburbs in the case of ozone during heatwaves. The inclusion of urban tree emissions improves the estimation of OM concentrations compared to in situ measurements, but they are still underestimated as trees are still missing from the inventory. OM concentrations are sensitive to terpene emissions, highlighting the importance of favoring urban tree species with low-terpene emissions.

Uptake and Transport of Selenium in a Soil–Tea Plant–Tea Infusion System: A Study of Typical Tea Plantations in a Selenium-Rich Area of China

Selenium is an important indicator for the evaluation of tea quality. However, the relationship between selenium uptake by tea plants (Camellia sinensis) and soil properties, as well as selenium transport and distribution in a tea plantation soil–tea plant–tea infusion production system, remain unclear. In this study, 12 tea plantations situated in a typical selenium-rich area of China were selected, and the characteristics and crucial factors influencing the uptake and transport of selenium were analyzed using a plantation soil–tea plant–tea infusion production system. The soil total selenium content ranged from 1.12 to 6.67 mg kg−1, with an average of 2.57 mg kg−1. The average available selenium content was 53.56 µg kg−1, and the activation rate of soil selenium was 2.27%. Soil-available selenium was significantly positively correlated with total selenium, available potassium, and soil organic matter contents, and was significantly negatively correlated with soil pH. The selenium content in old leaves ranged from 0.29 to 2.73 mg kg−1, which met the standard for selenium-rich tea, whereas only 33% of young leaves met this standard. The selenium enrichment factor was highest in the fibrous root and lowest in the young leaves. The average selenium transport factors from fibrous roots to main roots, from main roots to main stems, from main stems to lateral stems, from lateral stems to young leaves, and from lateral stems to old leaves were 0.53, 0.92, 0.67, 0.97, and 2.30, respectively. The selenium concentration of tea infusion ranged from 1.88 to 12.49 μg L−1, and the average selenium dissolution rate was 22.62% after one brewing. This study identified critical factors that influence soil-selenium availability. The selenium content in tea plant organs is indicated to be strongly associated with the selenium content in the main roots.

Those That Remain Caught in the “Organic Matter Trap”: Sorption/Desorption Study for Levelling the Fate of Selected Neonicotinoids

With projections suggesting an increase in the global use of neonicotinoids, contemporary farmers can get caught on the “pesticide treadmill”, thus creating ecosystem side effects. The aim of this study was to investigate the sorption/desorption behavior of acetamiprid, imidacloprid, and thiacloprid that controls their availability to other fate-determining processes and thus could be useful in leveling the risk these insecticides or their structural analogues pose to the environment, animals, and human health. Sorption/desorption isotherms in four soils with different organic matter (OC) content were modelled by nonlinear equilibrium models: Freundlich’s, Langmuir’s, and Temkin’s. Sorption/desorption parameters obtained by Freundlich’s model were correlated to soil physico-chemical characteristics. Even though the OC content had the dominant role in the sorption of the three insecticides, the role of its nature as well as the chemical structure of neonicotinoids cannot be discarded. Insecticides sorbed in the glassy OC phase will be poorly available unlike those in the rubbery regions. Imidacloprid will fill the sorption sites equally in the rubbery and glassy phases irrespective of its concentration. The sorption of thiacloprid at low concentrations and acetamiprid at high concentrations is controlled by hydrophilic aromatic structures, “trapping” the insecticides in the pores of the glassy phase of OC.

Validation and Application of the Diffusive Gradients in Thin-Films Technique for In Situ Measurement of β-Blocker Drugs in Waters and Sediments

The occurrence of β-blocker drugs in aquatic environments worldwide has caused increasing attention to their threat to human health in recent years. It is essential to monitor these widely prescribed pharmaceuticals in natural waters and sediments, helping us investigate their potential risk to humans and ecosystems. In this study, a passive sampling technique, diffusive gradients in thin-films (DGT), was systematically developed for eight frequently detected β-blockers. The effective capacities of target compounds were large enough for the devices to deploy for several weeks. The uptake of all compounds was linearly correlated with deployment times during the 7-day laboratory experiment and agreed well with the theoretical line, except for several compounds (e.g., ATL) due to their relatively slow uptake rate. The performance of most compounds was independent of varying pH values and organic matter contents; only a few compounds were affected, while the application in high-salinity environments needs to be conducted with caution. Field deployments of DGT to detect β-blockers in situ in rivers and sediments proved that DGT is an effective tool to monitor β-blocker drugs and their fate in the natural aquatic environment, while DGT probes can provide information for us to investigate the biogeochemical processes occurred in sediment, especially at the sediment–water interface. This novel approach will help us understand the behaviour of β-blocker drugs in the aquatic environment, assess their risks, finally protect human health and maintain the sustainable development of the ecosystem.

Petroleum Potential Prospectivity of Muglad Basin, South Sudan: A Case of Source Rocks Characterisation in the Drilled Kaikang West-1 Well

This study focuses on Prospectivity of Petroleum Potential of Muglad basin, South Sudan, with the help of petroleum source rocks characterisation in the drilled Kaikang West-1 Well based on the organic matter quantity, quality, and the thermal maturation generation capability of the organic matter disseminated in the analysed rock samples. Muglad basin is a major petroliferous Western and Central African Rifts System (WCARS) member, with estimated reserves of 2,053 mm bbl. Muglad Basin comprises thick sandstones of Aradeiba and Bentiu Formations, considered to be the main petroleum prospectivity targets, with trapping mechanism being structural faults and lithological anticlines. The organic matter contents were determined directly from laboratory analyses of the source rock samples with the help of seismic and gamma ray profiles, total organic carbon (TOC wt %), maturity indices (OI, HI and PI), temperature maximum (Tmax °C), porosities and other sedimentological parameters. This study involved a series of analytical geochemistry and petro-physical studies to ascertain a number of effective source rock samples from the well cores which were then analysed in terms of TOC, OI, PI, HI, S2, S1 and Tmax to determine oil/gas prone samples (resource areas). These were then distinguished from strata with very high organic matter samples as well as very high TOC to help identify for possible source rock characterizations within the lithology pertaining to the well in terms of potential source-reservoir-seals combinations. The Rock-Eval pyrolysis data were useful in assessing and evaluating the type of organic matter, thermal maturity, and the generation capability of source rocks for hydrocarbon exploration rationale. The analyses revealed that some strata, within the sampled well data, have high hydrocarbon generation potential with the existence of commercial hydrocarbon production

Practical applications of spent mushroom compost in cultivation and disease control of selected vegetables species

AbstractMushroom cultivation is an important branch of the agricultural industry, and global mushrooms production has increased more than sixfold in the last decade. This industry uses large amounts of agricultural, forestry, livestock, and industrial wastes and their by-products. However, it also generates millions of tons of spent mushroom compost (SMC) (approximately 100 million tons per year) which has emerged as a significant issue that hinders the growth of the mushroom business and impacts the environment. Many crop diseases, which cause significant economic losses, are introduced by soil-borne plant pathogens. Spreading spent mushroom compost (SMC) to agricultural soils is a natural way to control plant diseases. Using organic waste material instead of chemicals, which is the most widely used method in agriculture today, is also a more environmentally responsible option. The generated SMC can potentially be used as a soil conditioner, an organic fertilizer, and suitable medium for growing various vegetable crops. The application of SMC has been found to be beneficial in the control of crop diseases by inducing microbiostasis, direct toxicity, or by inducing systemic resistance of the host plant. In the current review, the practical application of SMC in the cultivation of tomato, pepper, lettuce, cucumber, and eggplant was addressed. The application of SMC as a soil amendment showed a significant improvement in soil properties, including soil NPK, organic matter content, and soil beneficial microorganisms. Our review indicated that SMC could be used as a low-cost, alternative growing medium in vegetable production or as a soil amendment to add nutrients and restore soil fertility in agricultural lands. The SMC may be able to replace peat, a non-renewable natural resource, and thereby mitigating the adverse effects of excessive peat extraction in wetlands, bogs, marshes, and peatlands. This review uses unique data on the effective use of SMC in agricultural disease management, reducing the need for chemical pesticides that have adverse effects on both the environment and human health. It also provides a safe method for reusing, recycling, and integrating SMC into a circular economy that reduces its negative environmental effects and carbon footprint impacts. This work also offers a novel application of SMC as a low-cost substitute for peat or other growing media that pose environmental risks. Graphical abstract

Optimization Study of Soil Organic Matter Mapping Model in Complex Terrain Areas: A Case Study of Mingguang City, China

Traditional soil organic matter mapping is mostly polygonal drawing, which is even more difficult to accurately depict in complex terrain areas. The spatial distribution of soil organic matter is closely related to agricultural production, natural resources, environmental governance, and socio-economic development. Efficiently, economically, and accurately obtaining information on changes in soil organic matter in areas with diverse topography is an urgent problem to be solved. Mingguang City has a high research value because of its unique topography and natural landscape. To solve the problem of soil organic matter mapping in this area, this study will construct an excellent organic matter prediction model. Using 173 soil survey samples (123 for training and 50 for testing), the optimal feature variable subsets selected from 31 environmental variables through Pearson correlation, stepwise regression-variance inflation factor, and recursive feature elimination models based on different algorithms were employed. Each selected feature subset was then used to construct organic matter prediction models using multiple advanced machine learning algorithms. By comparing accuracy validation and model performance, the organic matter prediction model suitable for Mingguang City (RFE-RF_SVM) was obtained, that is, the prediction model of organic matter based on support vector machines with the feature variables screened by the feature recursive elimination algorithm of random forest with RMSE = 3.504, VSI = 0.036, and R-squared = 0.730. Furthermore, the analysis focused on assessing the significance of the predictive factors. The mapping results of this study show that the soil organic matter content in the central and northwestern parts of the study area is low, and the reasons for this situation are different. The central part is mainly caused by the change of land use and topography, while the northwestern part is caused by the loose soil structure caused by the parent material. The government can take targeted measures to improve the soil in the areas with poor organic matter.

Application of Panchagavya, a Cow-based Liquid Formulation, as a Lever for Sustainable and Enhanced Vegetable Crop Production: A Review

Panchagavya, a fermented liquid bio-formulation derived from cow-based products such as dung, urine, milk, curd and ghee, has recently gained importance in agricultural practices due to its reported effectiveness in enhancing vegetable crop production. Its formulation involves a fermentation process that harnesses the diverse microbial communities present in cow-derived substances, resulting in a potent nutrient-rich solution that is believed to possess plant growth-promoting properties. One of the primary mechanisms underlying its efficacy lies in the diverse array of microorganisms present in the formulation. These microorganisms, including beneficial bacteria, fungi and actinomycetes, play crucial roles in nutrient cycling, disease suppression and soil conditioning. Additionally, Panchagavya contains plant growth-promoting substances such as hormones, enzymes, vitamins and amino acids, which contribute to enhanced nutrient uptake, root development and overall plant vigour. Furthermore, application of Panchagavya has been shown to improve soil health by enhancing microbial activity, increasing organic matter content and improving soil properties. These soil improvements not only benefit the current crop but also have long-term positive implications for soil fertility and sustainability. This multifaceted approach to crop management offers a holistic solution to enhance crop productivity while reducing reliance on synthetic inputs. This review aims to comprehensively analyse the literature on the effects of Panchagavya on vegetable crops, highlighting its mechanisms of action and potential benefits for increased vegetable crop production.

Ecological Studies on the Soil and Vegetation of Krusadi Group of Islands in the Gulf of Manaar

The account presents the plant ecology with a description of soils and other related features of the Krusadi group of islands situated in the Gulf of Manaar approximately between 9°14'-9°15'N and 79°10.5'-79°14.5' E. Data on pH, organic matter contents, total soluble salts, sodium chloride contents and calcium carbonate contents in the soils of different habitats are presented in tabular form and an attempt made to correlate vegetation with the soil features. A classification of vegetation situations rather than strictly vegetation type has been brought out and comparison made with the main neighbouring island of Rameswaram with similar climate. The paper includes a vegetation map of the area prepared during the field work.

Biofertilization with Liquid Vermicompost-Activated Biochar Enhances Microbial Activity and Soil Properties

Biochar (Bc) and liquid vermicompost extracts (LVEs) are increasingly being used as biofertilizers in agriculture to promote soil-microbe-crop interactions. However, although both these products can potentially act synergistically due to their complementary characteristics, their co-application in different soils has not yet been investigated. Therefore, firstly, an LVE-activated biochar (BLVE) was experimentally formulated and the persistence of LVE bacteria over a 60-day storage period was determined. The total number of LVE bacteria increased by 10-fold after 7 days and was stable throughout the entire biochar storage period. In addition, changes in the composition of the bacterial community were observed after 30 days of storage, indicating that taxa less represented in pure LVE may be advantaged upon biochar colonization. Secondly, a microcosm experiment was performed to evaluate whether the biological fertility and enzyme activities of two soils, differing in organic matter content, could be enhanced by the addition of LVE-activated biochar. In this experiment, three different doses of Bc, LVE, and BLVE against the carbon-related biological fertility index (i.e., biological fertility index, BFI) and three enzyme activities over a 21-day incubation period were tested. The BLVE treatment yielded the best results (i.e., BFI +32%, enzyme activities +38%). This indicates that Bc and LVEs can act synergistically to promote soil fertility, quality, and microbial activity. By integrating LVE-activated biochar into their soil management practices, farmers could achieve higher crop yields and healthier products.

Nematode community structure in sugarcane fields under continuous vinasse fertigation

Sugarcane vinasse is a residue from ethanol production, which has high content of nutrients and organic matter, improving chemical, physical and biological changes in the soil. This study evaluated nematode community structure, food web, metabolic footprint, and soil quality in sugarcane fields under continuous vinasse fertigation. Soil samples were collected from four sugarcane fields in Pernambuco State, Brazil, under continuous vinasse fertigation for nematode identification at the genus (plant parasites) and family (free-living) level, physical and chemical analyses of the soil. Nine genera of plant-parasitic nematodes and five families of free-living nematodes were identified in sugarcane fields. Plant-parasitic nematodes were dominant, except in the field with five years of continuous vinasse application. The genera Mesocriconema, Meloidogyne, Helicotylenchus and Pratylenchus were frequent in all fields. Predators and fungivores nematodes were few abundant, although, according to the soil food web, all sugarcane fields were low to moderately disturbed environments. A positive correlation was observed between the microbial respiration and Rhabdtidae in fields with five years of vinasse application, and between the electrical conductivity of the soil and Meloidogyne in fields without vinasse application. We highlight those alterations in the structure and composition of the nematode community, and soil characteristics that can occur due to vinasse fertigation in sugarcane fields.

The Impact of 9 Years of Swine Wastewater Application on the Mineral and Organic Quality of Soil in Various Agricultural Crops

This study evaluates the long-term effects of swine wastewater (SWW) on relevant parameters for soil fertility, including calcium (Ca), magnesium (Mg), potassium (K) cations, cation exchange capacity (CEC), and organic matter (OM) in an agricultural area with 9 years of crop cultivation. Three types of SWW (raw, after leaving the biodigester, and after the manure plant) were analyzed with four application rates of SWW (0, 100, 200, and 300 m3.ha−1), associated or not with mineral fertilization, resulting in eight treatments. The study found that the long-term use of SWW had significant effects on soil parameters. Principal component analysis (PCA) was used to summarize the data. The soil’s calcium (Ca), magnesium (Mg), and cation exchange capacity (CEC) levels were higher in soybean compared to other crops and natural soil. Similarly, the treatment with 0 m3.ha−1 of pig manure and without mineral fertilization showed higher levels of these nutrients. In contrast, potassium (K) was found in greater quantities in oats, SWW from the biodigester, higher doses of manure, and with mineral fertilization. The crops had a higher organic matter (OM) content compared to the natural soil, with corn and raw SWW showing the most significant increase.

Palm Oil Mill Effluent Disposal and Its Utilization in Agricultural Soil

In the study, soil samples were impacted with 10%, 50% and 100% (v/w) of the palm oil mill effluents. Soil physicochemical properties, soil stress marker enzymes, soil bacteria populations were studied using standard methods. Analysis of the physicochemical properties of the Palm oil mill effluent (POME) showed that POME in the presence of the reference showed the following: pH, conductivity, BOD5, TDS, TSS, TS at 5.67 ±0.014a , 610±0.023c , 4.87±0.025b, 372.1±0.015c , 539.55±0.04a, 911.6±0.032b mg/ml, respectively dissolved mineral such as Magnessium (Mg), potassium (K), calcium (Ca) and phosphate (PO3) were recorded at 9.82±0.05b , 14.52±0.05a, 13.23±0.04c and 8.69±0.01bc mg/ml respectively. Total organic carbon and organic matter contents were recorded at 81.87±0.01a and 100.7±0.02c mg/ml respectively. Organismal proliferation increase as the percentage of the POME per gram of the soil increase from 10-50% (v/w) while a downturn in the organismal counts decreases significantly at 100% (v/w). There was a noticeable decrease in the coliform counts/g of the organisms as the incubation days increases from day 0-14. Enzyme activity relatively decreases as the contaminant concentrations increases from 0-100 v/w. Lipases activity was seen relatively low in all the soil at low concentrations of the effluents (0-50 v/w). At high concentrations of the effluents, there was a significant increase in the enzyme activity. POME can be utilized as sustainable source of organic agro fertilizer when quantified; however poor incentive by peasant farmers may lead to abysmal utilization of the waste water and its negative impact in the soil with aftermath of low soil fertility and poor agricultural productivity.