Soil Content Research Articles

Morfologi Terung (Solanum melongena L.) Pada Berbagai Dosis Biochar Sekam Padi dan Penambahan Pupuk Organik Cair

Eggplant production in Indonesia remains relatively low and has not been able to meet market demands. Long-term use of inorganic fertilizers has led to declining organic matter content in soil, soil degradation, and environmental pollution. To address these issues, agricultural waste such as rice husk can be converted into charcoal or biochar to improve soil quality degraded by excessive use of chemical fertilizers. In addition to biochar as organic material, other organic inputs like liquid organic fertilizer can potentially improve soil physical properties. This research aims to determine the effect of giving rice husk biochar and the correct dose, to find out the effect of applying liquid organic fertilizer and the right concentration and to find out the interaction between giving rice husk biochar and liquid organic fertilizer on eggplant growth and production.The study employs a Randomized Block Design (RBD) factorial with 2 treatment factors. The first factor involves rice husk biochar application at 4 levels (A0: control, A1: 0.6 tons/ha or approximately 30 g/plant, A2: 1.2 tons/ha or approximately 60 g/plant, and A3: 1.8 tons/ha or approximately 90 g/plant). The second factor is liquid organic fertilizer application at 4 levels (B0: control, B1: 0.1 mg/l, B2: 0.3 mg/l, and B3: 0.5 mg/l). The results of the study indicate that rice husk biochar application can increase plant height and leaf number, the best dose for rice husk biochar is 90 g/plant.Application of liquid organic fertilizer has not been able to affect plant height and number of eggplant leaves. Keywords : eggplant, rice husk biochar, liquid organic fertilizer

Exopolysaccharide-Producing Bacteria Regulate Soil Aggregates and Bacterial Communities to Inhibit the Uptake of Cadmium and Lead by Lettuce

The accumulation of heavy metals in the soil not only causes serious damage to the soil ecosystem, but also threatens human health through the food chain. Exopolysaccharides have the functions of adsorbing and chelating heavy metals and reducing their bioavailability in the soil. In our study, exopolysaccharide-producing bacteria with a high efficiency in adsorbing cadmium (Cd) and lead (Pb) were screened from heavy metal-contaminated farmland. Through pot experiments, the influence of functional strains on the size distribution, heavy metal content, and bacterial community structure of soil aggregates in lettuce was studied using high-throughput sequencing technology. The results show that 11 strains secreting exopolysaccharides were initially screened from heavy metal-contaminated soil. Among them, strain Z23 had a removal rate of 88.6% for Cd and 93.2% for Pb. The rate at which Cd was removed by strain Z39 was 92.3%, and the rate at which Pb was removed was 94.4%. Both strains belong to Bacillus sp. Strains Z23 and Z39 induced the formation of Fe2Pb(PO4)2, Cd2(PO4)2, and Pb2O3 in the solution. The pot experiments showed that strains Z23 and Z39 increased (19.1~23.9%) the dry weight and antioxidant enzyme activity of lettuce roots and leaves, while reducing (40.1~61.7%) the content of Cd and Pb. Strains Z23 and Z39 increased the proportion of microaggregates (<0.25 mm) and the content of exopolysaccharides in rhizosphere soil and reduced (38.4–59.7%) the contents of available Cd and Pb in microaggregates, thus inhibiting the absorption of heavy metals by lettuce. In addition, the exopolysaccharide content and the bacterial community associated with heavy metal resistance and nitrogen (N) cycling (Patescibacteria, Saccharimonadales, Microvirga, and Pseudomonas) in microaggregates were key factors affecting the available heavy metal content in soil. These results show that the exopolysaccharide-producing bacteria Z23 and Z39 reduced the absorption of Cd and Pb by lettuce tissues, thus providing strain resources for the safe utilization of soils that exceed heavy metal standards for farmland and for reducing the heavy metal content in vegetables.

The Jyndevad Experiment: Revealing long-term interactions between liming and phosphorus fertilization in a coarse sand soil

The Jyndevad field experiment, initiated in 1942 on a coarse sand soil in South of Denmark, explores the effect of four liming levels (0, 4, 8 and 12 Mg lime ha−1). These were in 1944 combined with two levels of mineral phosphorus (P) fertilizer (0 and 15.6 kg P ha−1 year−1), with or without a high initial dose of 156 kg mineral P ha−1. This study assesses interactions between liming and P fertilization on soil pH, Olsen-P contents and barley yields covering the last three decades. Annual P application improved barley yield regardless of liming, but the optimal liming level differed from year to year. This emphasizes the need for long-term field experiments to detect the complex interactions between liming and P availability on crop performance. The initial high P dose in 1944 and annual P fertilization increased Olsen-P contents in soil. The unlimed soil with pH(CaCl2) values below 4 had the highest Olsen-P content. The Jyndevad Experiment now harbors wide gradients in soil P (Olsen-P contents: 9–82 mg P kg−1 soil) and pH (3.6–6.9), providing a unique research platform for future studies on interactions between liming and P fertilization on coarse sand soils. We present a selection of studies that have used the Jyndevad Experiment to illustrate the research potential of the experiment.

Improvement of Salt Leaching Efficiency and Water Content of Soil through Irrigation with Electro-Magnetized Saline Water

While the advantageous effects of using magnetic and electromagnetic treatment (ET) of brackish and saline waters on soil salinity reduction in the root zone were largely reported, more studies are needed to answer questions about the soil salt leaching efficiency and the effect of the duration of the exposure to ET. For this aim, pot experiments were conducted using an Aqua-4DR physical water treatment device. The first experiment included two trials. The first trial considered five concentrations: C0:1.0; C1:4.5; C2:9; C3:13.5; and C4:18 dS m−1. The results revealed that the volume and the salt concentrations of the drained waters were significantly higher under irrigation with ET saline waters than those provided by untreated waters. The drained fraction of water varied from 20 to 26% under irrigation with untreated water and increased from 33 to 56% under irrigation with electro-magnetized water, indicating an improvement in the salt leaching. The second trial was carried out with different irrigation doses. The results showed that the higher the dose, the more obvious and significant the ET effect. The different treatment durations of water exposure revealed that the volume and salinity of drained water significantly increase as the ET duration increases. An increase in the ET duration also induces an increase in the soil water content of around 2.5%. Based on the experimental findings, we may conclude that the ET of saline water can reduce the adverse effect of salinity on the top soil, but these leached salts are carried away in depth and there is no concentration limit of water to the effect of the ET.

Innovative Design and Optimization of High-Quality Peanut Digging-Inverter

To rapidly dry peanut pods and effectively address mold issues resulting from rainy weather, this article provides an analysis of the current research status of global peanut digging, inverting, and harvesting technologies. Based on a two-stage peanut harvesting model, the operating principles of a high-quality peanut digging-inverter are elaborated upon, and the design of key machine components is discussed. The evaluation metrics for the operation of a high-quality peanut digging-inverter include the rate of vine inverting, the soil content rate, the rate of fallen pods, and the rate of buried pods. Utilizing theoretical analysis, the Box–Behnken experimental design is employed to investigate the operating parameters of these machines, with the tractor’s running speed, the linear speed of the inverting roller, and the linear speed of the conveyor chain serving as the experimental factors in a three-factor, three-level experimental study. A regression model is established to analyze the impact of each factor on operational quality and to comprehensively optimize the influencing factors. The experimental results indicate that all factors significantly affect the rate of vine inverting. The tractor’s running speed (X1) and the linear speed of the inverting roller (X3) significantly influence the rate of buried pods, while the linear speed of the conveyor chain (X2) does not have a significant effect on this rate. Similarly, the tractor’s running speed (X1) and the linear speed of the inverting roller (X3) significantly affect the rate of fallen pods, whereas the linear speed of the conveyor chain (X2) does not. Furthermore, the linear speed of the conveyor chain (X2) and the linear speed of the inverting roller (X3) significantly impact the soil content rate, while the tractor’s running speed (X1) does not. The optimal combination of operating parameters is a tractor running speed of 1 m/s, a conveyor chain linear speed of 1.3 m/s, and an inverting roller linear speed of 2.1 m/s. Under these conditions, the high-quality peanut digging-inverter achieves a vine inverting rate of 89.29%, a buried pod rate of 0.31%, a fallen pod rate of 0.74%, and a soil content rate of 8.11%. The experimental values for each evaluation index exhibit relative errors of 1.14%, 6.45%, 1.35%, and 0.13% compared to the optimized values provided by the Design-Expert software. The findings of this research will facilitate the development of hardware conditions for the future intelligent and information-based harvesting of peanuts, thereby establishing a solid foundation for the high-quality initial processing of oilseeds.

Amelioration of Soil Fertility by the Application of Different Fruit Waste Composts

The soil health status of Bangladesh decreased day by day, particularly organic matter and major nutrient content. The organic matter content in most of the agricultural soil in Bangladesh is <2%, which indicates poor soil health condition. In Bangladesh, almost every day, an enormous amount of waste material is produced from different kinds of seasonal and unseasonal fruit’s peels. Lack of proper recycling methods, most of these wastes are thrown away in drains, cannels, rivers, etc. which indicates a major threat to environmental safety. Composts derived from the wastes of different fruit’s peels can be an excellent source of organic matter and essential nutrients for soil health improvement. Therefore, the present study was carried out to evaluate the changes in physicochemical properties and nutrient contents of experimental soil treated with compost prepared from different types of fruit’s waste. The compost was prepared accordingly using different types of fruits waste and then the collected compost was thoroughly mixed with the soil and kept for six months. The experimental treatment consisted of three organic composts (jackfruit peel compost, mango peel compost, and banana peel compost) and three rates of application (1000, 1500, and 2000 kg ha-1). The experiment was arranged in a factorial completely randomized design and replicated thrice. The analyzed data showed that, the physicochemical properties and nutrient contents of experimental soil varied significantly with the use of different types of fruit’s wastes compared to no waste added soil, except in the case of particle size. Soil mixed with mango peel compost at a rate of 2000 kg ha-1 resulted in a higher available N content (2520 mg kg-1) and available P content (42.56 mg kg-1), whereas the available K content (219.88 mg kg-1), EC (1.55 dS m-1) and CEC (1209.56 meq 100g-1) were found higher in soil treated with banana peel compost of 2000 kg ha-1. On the other hand, soil treated with jackfruit peel compost of 1500 kg ha-1 showed the higher available Ca content (1533.33 mg kg-1) and the jackfruit peel compost of 2000 kg ha-1 resulted in the higher organic carbon (1.98%) and organic matter (3.41%). The findings of this experiment revealed that, compost prepared from different types of fruit peels can be an excellent source of organic matter and nutrients and among the tested composts, mango peel compost was better to improve the physiochemical properties of soil and supply sufficient nutrients for plant growth.

Evaluating soil quality and carbon storage in Western Ghats Forests, Karnataka, India, for sustainable forest management.

Monitoring soil quality index (SQI) and soil organic carbon (SOC) stock status of the Western Ghats (WG) forests in India is crucial for providing vital ecosystem services alongside sustainable forest management practices. However, comprehensive profile data on SQI and SOC stock across different forest types under WG forests are limited. The study evaluated SQI and SOC stock under three forest types, i.e. tropical wet evergreen (TWE), tropical semi-evergreen (TSE), and tropical moist deciduous (TMD) across WG in Karnataka. SQI was assessed using principal component analysis with two indexing approaches and scoring methodologies, with weightage indexing through nonlinear scoring functions (NLSF) showing superiority over other methodologies. TMD forests exhibited the highest SQI, followed by TWE and TSE, while the lowest was observed in Rippon Pet RF (0.36 surface, 0.28 control section), primarily due to limitations in organic carbon and clay content. SOC stock mirrored SQI trends (TMD > TWE > TSE), with the highest values in Kollegal RF (339.3 MG ha-1) and lowest in Rippon Pet RF (102.5 MG ha-1). Although SOC and SQI were established to be ideal indicators for dynamic ecosystem services (ESs), high OC content in surface soils of Poomale NF induces pedogenic acidification and Al toxicities, indicating potential forest soil degradation. Significant correlation with control section SQI and SOC (p < 0.05) emphasises monitoring subsurface soil status to identify soil degradation, sustainable forestry practices, and complex ESs in forest systems.

Soil Analysis by Mobile Multinuclear NMR: Quantification of Phosphorus, Aluminum, and Sodium.

Soil analyses are essential to ensure economically and environmentally sustainable crop production while maintaining the soil fertile for future use. Unfortunately, common soil analyses may be highly demanding in terms of time, chemicals, and costs. This applies, in particular, when total quantities of elements are desired. As an easy and fast alternative without consumption of chemicals, we here present mobile 31P, 27Al, 23Na, and 1H NMR for quantification of phosphorus, aluminum, and sodium contents in soil. This enables accurate on-site analysis and is suitable for direct measurement on fresh, undried soil samples since the water content is quantified as well. For demonstration, 40 various Danish agricultural soil samples were analyzed using a mobile NMR sensor, and the results were compared with external laboratory analyses for P, Al, and Na. The laboratory analyses were conducted with ICP-OES after four-acid digestion, which additionally were compared with aqua regia digestion, showing inadequacies in the performance of the latter. Good agreement between NMR and laboratory analyses (correlation coefficients 0.91 for P, 0.98 for Al, and 0.90 for Na, in the concentration ranges 250-1200 ppm P, 1.4-5% Al, and 0.3-1% Na) were obtained with high accuracy using NMR measuring times of 20 min to 1 h for P, 4-12 min for Al, and 6-20 min for Na. Additionally, the NMR measurements provide information on the amount of P associated with paramagnetic centers (e.g., Fe3+). Good correlations were also observed to other parameters such as the clay content, which is predictable from the intensity of the more fast-relaxing of three 27Al NMR components.

The Degradation of Polyethylene by Trichoderma and Its Impact on Soil Organic Carbon

Polyethylene mulching film, which is widely utilized in arid and semi-arid agriculture, leaves residual pollution. A novel approach to addressing this issue is microbial degradation. To screen the strains that degrade polyethylene efficiently and clarify the effect of degrading strains on the turnover of soil organic carbon, a polyethylene-degrading fungus PF2, identified as Trichoderma asperellum, was isolated from long-time polyethylene-covered soil. Strain PF2 induced surface damage and ether bonds, ketone groups and other active functional groups in polyethylene, with 4.15% weight loss after 30 days, where laccase plays a key role in the degradation of polyethylene. When applied to soil, the Trichoderma-to-soil weight ratios were the following: B1: 1:100; B2: 1:200; B3: 1:300 and B4: 1:400. Trichoderma asperellum significantly increased the cumulative CO2 mineralization and soil organic carbon mineralization in the B1 and B2 treatments compared with the control (B0). The treatments B1, B3 and B4 increased the stable organic carbon content in soil. An increase in the soil organic carbon content was observed with the application of Trichoderma asperellum, ranging from 27.87% to 58.38%. A positive correlation between CO2 emissions and soil organic carbon was observed, with the soil carbon pool management index (CPMI) being most correlated with active organic carbon. Trichoderma treatments improved the CPMI, with B3 showing the most favorable carbon retention value. Thus, Trichoderma asperellum not only degrades polyethylene but also contributes to carbon sequestration and soil fertility when applied appropriately.

Plant growth promoting bacteria promote rice growth cultivated in two different sandy soils subjected distinct climates conditions.

Sandy soils contain around 70% sand in their composition, making them highly fragile and susceptible to land degradation. Practices such as no-tillage cultivation, the use of bioinoculants, and the application of organic amendments can restore the organic matter in these soils, ensuring sustainable production. In this context, this work aimed to study the microbiological aspects of two sandy soil areas (Brazilian Northeast and South) under contrasting climatic conditions (tropical and temperate). With this purpose, prokaryotic communities were evaluated, and the plant growth-promoting potential of isolated bacteria was assessed by rice inoculation in sandy soil. Despite the high sand content in both soils, soil from the NE was related to the highest phosphorous, calcium, potassium, copper, sodium, zinc, magnesium, and manganese contents, organic matter percentage, and pH. The Shannon diversity index indicated that prokaryotic communities in NE were more diverse than in SU, and PCA revealed that microbial composition exhibited distinct patterns. The rice inoculation experiments were executed to verify if the bacterial isolates displayed a similar growth promotion potential when inoculated in sandy soil areas subjected to different climatic conditions. When all PGP characteristics evaluated were pooled in a PCA, a similar pattern was observed for SU and NE. Burkholderia sp. SU94 was related to highest PGP characteristics evaluated. Paraburkholderia sp. NE32 showed similar results to those of the non-inoculated control. This similar effect of rice growth in the Northeast and South of Brazil suggests that isolate SU94 adapts to different environmental conditions.

Rational Nitrogen Reduction Helps Mitigate the Nitrogen Pollution Risk While Ensuring Rice Growth in a Tropical Rice–Crayfish Coculture System

The incorporation of aquaculture feed within a rice–crayfish coculture system significantly enhances nitrogen cycling, thereby diminishing the reliance on chemical fertilizers. However, this benefit is often overlooked in practice, and farmers continue to use large quantities of chemical fertilizers to maximize production, resulting in excessive soil fertility and water nitrogen pollution. Thus, avoiding nitrogen pollution in rice–crayfish coculture systems has become a pressing issue. In this study, we conducted a two-year experiment with two rice cultivars, and a 33.3% reduction in nitrogen fertilizer in a rice–crayfish coculture system (RC), to systematically analyze the overall nitrogen balance, rice nitrogen nutrition, and soil fertility, as compared with a rice monoculture system (RM). Our findings revealed the following: (1) Under the 33.3% reduction in nitrogen fertilizer, the nitrogen surplus in the rice–crayfish coculture system was comparable to that in the rice monoculture, and was controlled at an environmental safety level. (2) Nitrogen utilization efficiency and the accumulation of nitrogen in the rice–crayfish coculture were comparable to those in the rice monoculture. The nitrogen cycle in this system was able to provide the nitrogen required for rice growth after nitrogen fertilizer reduction. (3) The rice–crayfish coculture significantly improved the overall soil fertility and the effectiveness of soil nitrogen nutrition. Furthermore, cutting off the application of nitrogen fertilizer after the mid-tillering stage effectively controlled the total nitrogen content in soil after rice maturity. In conclusion, reducing nitrogen fertilizer in a rice–crayfish coculture system is feasible and beneficial. It ensures rice production, reduces the risk of excessive nitrogen surplus and surface pollution, and promotes a greener, more environmentally friendly paddy field ecosystem.

Effect of Fertigation of Water-Soluble Fertilizers on Growth, Yield of Cowpea and Nutrients Availability in Soil under Rice-cowpea Cropping Sequence

A investigation was carried out to study the Growth and yield of cowpea and primary nutrients availability in soil as influenced by fertigation of water-soluble fertilizers under rice-cowpea cropping sequence. Hybrid rice was tested under aerobic condition during Kharif 2015-16 and 2016-17 with 16 treatments replicated thrice in randomized block design. The results indicated that, the treatment, 100% RDF through water soluble fertilizer at 8 DI was recorded significantly higher growth and yield determinants, higher seed yield (12.94 q ha-1) and haulm yield (26.17 q ha-1) of cowpea. Significant higher organic carbon (0.57 %) was recorded with the application 100% STCR dose with WSF through fertigation at 8 DI and higher available N (146.38 kg N ha-1 ), P2O5 (122.67 kg P2O5 ha-1 ) and K2O (130.17 kg K2O ha-1 ) content in soil recorded 100% water soluble fertilizers (WSF) applied at 4 DI. However, exchangeable calcium [3.51 cmol (p+) kg-1], magnesium [2.55 cmol (p+) kg-1], available sulphur [12.50 ppm] in soil were recorded with 100% conventional fertilizers applied plots through PoP. Significantly higher DTPA extractable Fe (18.45 mg kg-1) noticed with 100% STCR of WSF at 8 DI. However, significantly higher DTPA extractable Zn (1.44 mg kg-1) and Cu (0.57 mg kg-1) was recorded with the application of 100% RDF with WSF at 4 DI. Significantly higher DTPA extractable Mn (22.78 mg kg-1) noticed with 100% STCR of WSF at 4 DI.

Restoring degraded lands: the role of sewage sludge in modulating soil carbon and nitrogen dynamics

Sewage sludge presents significant amounts of organic matter and nutrients and is frequently considered an alternative input for recovering degraded soils. In this scenario, this study aimed to evaluate the impacts of disposing of increasing doses of sewage sludge on the dynamics of C and N in the soil of a degraded area. After the application of five doses of sewage sludge (0, 50, 100, 200, and 400 t ha-1) were evaluated over time (30, 90, 180, 270, and 360 days), the contents of soil C and N, microbial biomass, light organic matter, and humic fractions of soil organic matter. The results showed that sewage sludge contributed to the quality and recovery of degraded soil by providing increases in soil organic C, total N, nitrate, and ammonia contents, microbial biomass C and N, light organic matter, as well as in the C and N stocks in humic substances, especially in humin. Most of the increases in these variables associated with C and N dynamics remained even one year after the application of sewage sludge. The soil quality improvement demonstrates the potential of using sewage sludge in projects to recover degraded areas as an alternative for its final disposal.

Smart-Agri Advisor: Data-Driven Crop Recommendations for Enhanced Productivity and Sustainability

In today's farming, it's important to grow crops well and use methods that are good for the environment to meet the rising need for food worldwide. This paper introduces "Smart-Agri Advisor," a system that helps farmers choose the right crops by analysing real-time data about the environment, soil, and market trends. It looks at factors like Soil contents, temperature, humidity and rainfall, along with market demand, to help farmers make smart decisions. The system also uses IoT sensors to automate watering, manage resources better, and make farming more sustainable. This study looks at how well the Smart-Agri Advisor helps improve farming efficiency and matches farming methods with market needs. Keywords: Machine Learning, NumPy, scikit- Learn, TensorFlow, Keras, etc.

Physiological and biochemical responses in a cadmium accumulator of traditional Chinese medicine Ligusticum sinense cv. Chuanxiong under cadmium condition

Ligusticum sinense cv. Chuanxiong (L. Chuanxiong), one of the widely used traditional Chinese medicines (TCM), is currently facing the problem of excessive cadmium (Cd) content. This problem has significantly affected the quality and safety of L. Chuanxiong and become a vital factor restricting its clinical application and international trade development. Currently, to solve the problem of excessive Cd, it is essential to research the response mechanisms of L. Chuanxiong to Cd stress. However, there are few reports on its physiological and biochemical responses under Cd stress. In this study, we conducted the hydroponic experiment under 25 μM Cd stress, based on the Cd content of the genuine producing areas soil. The results showed that 25 μM Cd stress not only had no significant inhibitory effect on the growth of L. Chuanxiong seedlings but also significantly increased the chlorophyll a content (11.79%) and root activity (51.82%) compared with that of the control, which might be a hormesis effect. Further results showed that the absorption and assimilation of NH4+ increased in seedlings under 25 μM Cd stress, which was associated with high photosynthetic pigments. Here, we initially hypothesized and confirmed that Cd exceedance in the root system of L. Chuanxiong was due to the thickening of the root cell wall, changes in the content of the cell wall components, and chelation of Cd by GSH. There was an increase in cell wall thickness (57.64 %) and a significant increase in cellulose (25.48%) content of roots under 25 μM Cd stress. In addition, L. Chuanxiong reduced oxidative stress caused by 25 μM Cd stress mainly through the GSH/GSSG cycle. Among them, GSH-Px (48.26%) and GR (42.64%) activities were significantly increased, thereby maintaining a high GSH/GSSG ratio. This study preliminarily reveals the response of L. Chuanxiong to Cd stress and the mechanism of Cd enrichment. It provides a theoretical basis for solving the problem of Cd excessive in L. Chuanxiong.Graphical Physiological and biochemical mechanisms of L. Chuanxiong seedlings under Cd stress.

Arsenic content in tissues, Fungus combs, Herbs, Termite mounds and Soils of termites of the genus Macrotermes and assessment of the health risk associated with their food use in the industrial zone of the Societe Nouvelle Des phosphates du Togo (SNPT)

Arsenic is present in different environmental matrices of the phosphate mining and processing area of the Société Nouvelle des Phosphates du Togo; including termite tissues, termite waste, termite mounds, termite Fungus combs, soils and nearby herbs. Arsenic levels vary across matrices, with termite waste having the highest concentration (approximately 27.01 mg/kg) compared to the outside herbs, which have the lowest. Phosphate mining sites, including Hahotoé-Kpogamé and Akoumapé, have higher levels of As contamination in soils and termite tissues compared to the phosphate processing site. A positive correlation is observed between As levels in termite tissues and termite waste; suggesting an ability of termites to eliminate arsenic via their waste. Regarding health risks, the hazard quotient (HQ) for arsenic in termites exceeds 1, and for non-threshold effects, the excess individual risk (EIR) assessment gives EIR &gt; 10-4 in both adults and children; which would mean that termite consumption poses a significant health risk, including cancer risks for human populations, particularly children. However, it should be noted that the estimation in this study includes total As (organic and inorganic). Since the toxicological reference values were calculated on the basis of inorganic arsenic, which presents more hazard and whose fraction represents 10% of total As, the daily exposure dose values for adults and children represent 1.40.10-4 mg/kg/d and 1.02.10-4 mg/kg/d of inorganic arsenic, respectively. These doses will then become lower than the toxicological reference value (TRV) with the consequence of hazard quotient (HQ) lower than 1 and resulting in low risks of carcinogenic effects. It is therefore necessary to specifically determine the inorganic fraction to refine the risk assessment and to extend this study to other trace elements in the prospected area.

Effect of Plow Pan on the Redistribution Dynamics of Water and Nutrient Transport in Soils

Plow pans are an essential part of the agricultural soil structure. By adjusting the soil bulk density and plow pan height, the water and nutrient transport are dynamically redistributed. Plow pans play a crucial role in promoting crop growth, increasing yields, and supporting sustainable land management. In this study, a column experiment was conducted to investigate the effects of plow pan height (10 cm and 15 cm) and bulk density (1.2, 1.4, and 1.6 g cm⁻3) on soil nutrient and water leaching under high-volume (HV) and low-volume (LV) fertilizer applications. The results reveal that the leachate volume decreased by 61.9% at a plow pan height of 10 cm and by 96.2% at a plow pan height of 15 cm when the bulk density was increased from 1.2 to 1.4 g cm⁻3 under HV conditions. There was no leachate when the plow pan bulk density was 1.6 g cm−3. The reserved concentration of alkali-hydrolyzable N in the plow pan soils was the highest when the plow pan had a bulk density of 1.4 g cm−3 and a height of 15 cm. However, when the plow pan height was 15 cm, the available P content in the plow pan soils decreased by 27.0% and 21.0% at bulk densities of 1.4 g cm⁻3 and 1.6 g cm⁻3, respectively, when compared with 1.2 g cm⁻3. Furthermore, the available P concentrations in the plow pan and subsoil layers decreased with an increase in the plow pan height. The available K concentrations in the topsoil decreased by 26.8% and 24.0% when the plow pan bulk density was increased from 1.2 to 1.4 g cm−3 at heights of 10 and 15 cm, respectively. Thus, the optimal plow pan height and bulk density are closely related to the types of soil nutrients. However, it is clear that excessively high bulk densities (e.g., 1.6 g cm−3) negatively impact soil properties. For different nutrient requirements, a bulk density of 1.2 or 1.4 g cm−3 can be chosen, with each providing suitable options based on the specific nutrient needs. This research offers practical insights into changes in nutrient adsorption and fixation in agricultural production associated with alterations in plow pan bulk density.

Investigating the Spatial Patterns of Heavy Metals in Topsoil and Asthma in the Western Salt Lake Valley, Utah

Mining activities, particularly in large excavations like the Bingham Canyon Copper Mine in Utah, have been increasingly linked to respiratory conditions due to heavy-metal-enriched waste and dust. Operating continuously since 1906, the Bingham Canyon Copper Mine contributes 4.4% of the Salt Lake Valley PM2.5 pollution. However, the extent of its contributions to larger-sized particulate matter (PM10) dust, soil and water contamination, and human health impacts is largely unknown. Aerosol optical depth data from Sentinel-2 imagery revealed discernible dust clouds downwind of the mine and smelter on non-prevailing-wind days, suggesting potential heavy metal dispersion from this fugitive dust and subsequent deposition to nearby surface soils. Our analysis of topsoils from across the western Salt Lake Valley found mean arsenic, copper, lead, and zinc concentrations to be well above global background concentrations. Also, the minimum values for arsenic and maximum values for lead were well above the US EPA regional screening levels for residential soils. Thus, arsenic is the metal of greatest concern for impacts on human health. Elevated concentrations of all metals were most notable near the mine, smelter, and tailings pond. Our study linked these elevated heavy metal levels to regional asthma outcomes through cluster analysis and distance-related comparison tests. Significant clusters of high asthma rates were observed in regions with elevated topsoil heavy metal concentrations, impacting both low- and high-income neighborhoods. The findings of this preliminary study suggest that the mine, smelter, and recent construction activities, especially on lands reclaimed from former tailings ponds, could be contributing to atmospheric dust containing high levels of heavy metals and exacerbating asthma outcomes for residents. However, the methods used in the study with aggregated health outcome data cannot determine causal links between the heavy metal contents of soil and health outcomes; they can only point to potential links and a need for further investigation. Such further investigation should involve individual-level data and control for potential confounding factors, such as socioeconomic status, access to healthcare, and lifestyle factors, to isolate the effect of metal exposures on asthma outcomes. This study focused on atmospheric deposition as a source of heavy metal enrichment of topsoil. However, future research is also essential to assess levels of heavy metals in subsoil parent materials and local surface and groundwaters to be able to assess the links between the sources or methods of soil contamination and health outcomes.

How do reactive aluminum and iron phases control soil organic carbon and phosphate adsorption capacity in agricultural topsoils across Japan?

ABSTRACT The growing number of studies suggests that the prediction of soil organic carbon (SOC) storage and persistence can be improved by accounting for variations in soil reactive metal phases. Nevertheless, the dataset on reactive metals is often limited at a national scale. In Japan, the phosphate adsorption coefficient (PAC) has been measured for agricultural soils nationwide. PAC is known to be strongly controlled by reactive metals, and hence, it can be used as a surrogate for reactive metal content. However, the relationships between SOC, reactive metals and PAC across a wide range of agricultural soils remain unclear. We thus examined these relationships using agricultural topsoils taken from 115 sites across Japan, covering two major soil great groups, Andosols and Lowland soils, as well as various land uses and soil temperature regimes (7.2–19.1°C). For the whole dataset, PAC was strongly correlated with oxalate-extractable metals (Alox + 0.5Feox: Metalox, r = 0.83) and moderately with pyrophosphate-extractable metals (Alp + 0.5Fep: Metalp, r = 0.68). These results suggest a stronger contribution of short-range-order (SRO) minerals to PAC as the former parameter reflects the content of both SRO minerals and organically complexed metals, while the latter reflects only that of organo-metal complexes. Moreover, Metalp was the best predictor of SOC contents in both Andosols (r = 0.79) and Lowland soils (r = 0.65). When only soils at near neutral soil pH range were considered, the exchangeable Ca content also co-varied with SOC in Lowland soils (n = 17). Of the two metallic elements, reactive Al phases better explained the variation of SOC and PAC in Andosols, whereas reactive Fe phases also showed similar explanatory power for PAC in Lowland soils. Our analyses also suggested that soil group (esp. erosion intensity) and land use likely impacted the SOC-Metalox relationship in Andosols, whereas environmental factors such as soil temperature and soil redox regime affected those relationships in Lowland soils. Overall, we showed that PAC is a useful surrogate for SRO minerals and organo-metal complexes and, with careful considerations of the environmental and pedogenic factors, it is potentially useful to estimate the amounts of SOC stabilized by reactive metal phases in agricultural soils across Japan.

Penerapan Metode Enhanced Phytoremediation pada Lahan Bekas Tambang Emas Desa Tirta Kencana Kecamatan Bengkayang

Community gold mining activities using the amalgamation method cause soil pollution due to the use of mercury (Hg) to extract gold content which causes a decrease in soil quality and environmental damage. Enhanced phytoremediation is a method that can be applied to remove mercury levels with using the Cyperus kyllingia plant and adding supporting elements in the form of bacterial isolates that are resistant to mercury. This research aimed to determine the effectiveness of Cyperus kyllingia plants and bacterial isolates for removing mercury levels in mercury-contaminated soil, as well as observing the bacterial population and plant morphology during the research. Based on the research results, it is known that the best efficiency value for removing mercury levels is found in phytoremediation with the addition of bacterial isolates, namely 86.88%. The largest bacterial population was found in the phytoremediation reactor with the addition of bacterial isolates, namely 73.3 × 106 CFU/mL. The mercury content in polluted soil causes changes in plant morphology, namely the color of green plants changes to yellow, but plants can reproduce as indicated by an increase in the number of leaves and plant stems