Acidic Soil pH Research Articles

Different Species and Cultivars of Broad Beans, Lupins, and Clovers Demonstrated Varying Environmental Adaptability and Nitrogen Fixation Potential When Cultivated as Green Manures in Northeastern Portugal

The success of growing legumes as green manure depends on their spatial and temporal integration within agroecosystems, which minimizes competition with cash crops, and on their nitrogen (N) fixation potential. This study evaluated seven legume species for biomass production, N fixation, and suitability for use in cropping systems in northern Portugal. Oats (Avena sativa L.) were grown to estimate the N fixation using the difference method, as a non-legume reference crop is required for this purpose, and oats are widely grown in the region. The study was conducted over four cropping cycles (2021–2024) in two climate zones across four land plots. The results indicated that the biomass production and N fixation varied by the species/cultivar and cropping cycle, which was significantly influenced by spring precipitation. Broad beans (Vicia faba L.) failed to develop in one cycle on highly acidic soil (pH 4.9), showing negative N fixation values when calculated by the difference method. Conversely, the lupins maintained a relatively high level of N fixation across all the conditions, demonstrating strong environmental adaptability. Thus, the N fixation values across the four cycles ranged from −5.4 to 419.4 kg ha−1 for broad bean (cv. Favel), while yellow lupin (Lupinus luteus L.) exhibited average values between 204.0 and 274.0 kg ha−1. The percentage of N derived from the atmosphere (%Ndfa) ranged from −13.3 to 91.6, −39.4 to 85.8, 83.8 to 94.7, 74.9 to 94.3, 72.8 to 92.2, 23.1 to 75.8, and 11.7 to 21.7 for these species/cultivars. Due to their environmental adaptability, biomass production, and N fixation capacity, these legumes could be used as green manure in inter-rows of woody crops or in summer annual crops like tomatoes and maize, grown in winter as an alternative to fallow land. The lupins showed strong promise due to their environmental resilience.

Influence of Annual Ryegrass (Lolium multiflorum) as Cover Crop on Soil Water Dynamics in Fragipan Soils of Southern Illinois, USA

Fragipans are dense subsurface soil layers that severely restrict root penetration and water movement. The presence of shallow fragipan horizons limits row crop production. We hypothesized that the roots of cover crop might improve soil physiochemical properties and biological activity, facilitating drainage and increasing effective soil depth for greater long-term soil water storage. To evaluate annual ryegrass as one component of a cover crop (CC) mix for promoting the characteristics and distribution of soil water, on-farm studies were conducted at Marion and Springerton in southern Illinois, USA. Soil samples were collected at 15 cm increments to 60 cm (Marion) and 90 cm (Springerton) depths during the fall of 2022. Both sites had low total soil carbon and nitrogen contents and acidic soil pH (≤6.4). A soil water retention curve was fitted using the van Genuchten equation. At Springerton, the CC treatment increased saturated (thetaS) and residual (thetaR) soil water contents above those of the no cover crop (NCC) at the 60–75 cm and 75–90 cm depths. Changes in volumetric soil water content were measured using a multi-depth soil water sensor for the Springerton site during late July to early August of the soybean growing phase of 2022; NCC had higher soil water than CC within the 0–15 cm depth, but CC had higher soil water than NCC at the 30–45 cm depth. These findings indicate that cover crop mix has the potential to improve soil water movement for soils with restrictive subsoil horizon, possibly through reducing the soil hydraulic gradient between the surface and restrictive subsurface soil layers.

Evaluating the Liming Potential of Mytilus galloprovincialis Shell Waste on Acidic Soils

The sustainable management of aquaculture by-products is crucial for advancing circular economy practices. Mediterranean mussel shell waste, rich in calcium carbonate, presents a sustainable alternative to conventional liming materials, especially for mitigating soil acidification, a very important and common issue that limits crop productivity. This study evaluated the effectiveness of processed mussel shell waste in enhancing soil pH, organic matter, and nutrient availability. A 180-day pot experiment using highly acidic soil (pH < 4.5) collected from a local field was conducted in a Completely Randomized Design. Treatments involved two grain sizes of mussel shell powder (Fine: <1 mm; Coarse: 1–2 mm) at rates between 0.1 and 6%. Treated soil pH was measured monthly, whereas organic matter, available phosphorus (P), and exchangeable potassium (K) were measured at the beginning and the end of the experiment. The results revealed significant improvements in pH, organic matter, available phosphorus (P), and exchangeable potassium (K), particularly in the Fine Powder treatments. However, total nitrogen (N) remained unaffected. These findings highlight the potential of mussel shells as an eco-friendly and cost-effective amendment, advancing sustainable agriculture and waste recycling, thus contributing to broader conservation efforts by reducing the environmental footprint of aquaculture waste and supporting biodiversity and ecosystem resilience through sustainable resource management.

Soil pH-dependent efficacy of DMPP in mitigating nitrous oxide under different land uses

The emission pathways and intensities of nitrous oxide (N2O) vary across land uses, and the efficacy of mitigation measures may also differ. To investigate the key factors influencing the effectiveness of the nitrification inhibitor 3,4-Dimethylpyrazole phosphate (DMPP) in mitigating N2O under various land use conditions, we collected ten pairs of soils from tea plantations and adjacent cultivated land for laboratory incubation. As a complementary study, we conducted a meta-analysis based on 261 pairs of observations from 40 incubation studies to investigate the determinants of soil N2O mitigation by DMPP and to validate our experimental results. Results of the incubation experiment showed that DMPP was significantly less effective in mitigating N2O in tea plantation soils (73%) than in cropland soils (82%). Soil pH is a key factor influencing DMPP efficiency under different land use conditions. The lower pH of acidic tea plantation soils resulted in lower abundance and activity of ammonia-oxidizing bacteria (AOB). Under these low pH conditions, heterotrophic nitrification became an important source of N2O emissions in acidic tea plantation soils. As DMPP primarily inhibits AOB, it was less effective against heterotrophic nitrification, which likely contributed to its reduced efficacy in tea plantation soils compared to cropland soils. Our meta-analysis further confirmed the critical role of soil pH in determining DMPP effectiveness. The effect of soil pH on DMPP efficacy was mainly attributed to its regulation of heterotrophic and AOB-derived nitrification. These findings suggest that the field efficacy of DMPP in N2O abatement in tea plantations requires further investigation. Given the significant contribution of heterotrophic nitrification to N2O emissions in strongly acidic tea plantation soils, alternative N2O mitigation strategies should be explored.

Application of selenium to reduce heavy metal(loid)s in plants based on meta-analysis

Agricultural soils are currently at risk of pollution from toxic heavy metal(loid)s (HMs) due to human activities, resulting in the excessive accumulation of arsenic (As), cadmium (Cd), chromium (Cr), copper (Cu), iron (Fe), mercury (Hg), manganese (Mn), lead (Pb) and zinc (Zn) in food plants. This poses significant risks to human health. Exogenous selenium (Se) has been proposed as a potential solution to reduce HMs accumulation in plants. However, there is currently a lack of comprehensive quantitative overview regarding its influence on the accumulation of HMs in plants. This study utilized meta-analysis to consolidate the existing knowledge on the impact of Se amendments on plant HMs accumulation from contaminated soil media. The present study conducted a comprehensive meta-analysis on literature published prior to December 2023, investigating the effects of different factors on HMs accumulation by meta-subgroup analysis and meta-regression model. Se application showed an inhibitory effect on plant uptake of Hg (28.9%), Cr (25.5%), Cd (25.2%), Pb (22.0%), As (18.3%) and Cu (6.00%) concentration. There was a significant difference in the levels of HMs between treatments with Se application and those without Se application in various plant organs. The percentage changes in the HMs contents of the organs varied from −13.0% to −22.0%. Compared with alkaline soil (pH > 8), Se application can reduce more HMs contents in plants in acidic soil (pH < 5.5) and neutral soil (pH = 5.5–8). For daily food plants(e.g. rice, wheat and corn), Se application can reduce HMs contents in Oryza sp., Triticum sp. and Zea sp., ranging from 14.0–20.0%. Our study emphasizes that the impact of Se on reducing HMs depends on the single or combined effects of Se concentration, plant organs, plant genera and soil pH condition.

Converse Responses of Biochar Application on N2O Emissions in Soils at Different pH Values in a Subtropical Citrus Orchard

The aim of this study was to explore the effect of biochar on N2O emissions in soils with different pH levels. Soils with five pH levels (4.0, 5.1, 5.8, 6.6, and 7.2) were incubated in two conditions, with 0% biochar (CK) and 1% biochar (BC), for 23 days. N2O emissions were measured at nine time points, and soil chemical properties, AOA-amoA, AOB-amoA, nirK, nirS, and nosZ, were analyzed. Partial least squares path modelling (PLS-PM) was used to assess the effect of nitrification and denitrification pathways on potential N2O emissions. The results showed that biochar reduced N2O emissions in highly acidic soil (pH 4.0) but increased emissions in soils with pH values ranging from 5.1 to 7.2. In highly acidic soils, decreased N2O emission was associated with increased soil pH (p &lt; 0.05) and decreased dissolved organic carbon content (p &lt; 0.05), leading to higher nosZ gene abundance (p &lt; 0.05). Meanwhile, in acidic to neutral soils, biochar application increased soil pH (6.6–11.7%), dissolved organic nitrogen (5.9–29.5%), dissolved organic carbon (8.6–41.0%), stimulated AOB-amoA, nirK, nirS gene abundance (p &lt; 0.05), and thus increased N2O emissions. The results verified the influence of nitrification and denitrification genes on N2O production in soils with different pH values. In conclusion, biochar had different effects on N2O emissions based on soil pH, highlighting the need to consider pH when using biochar to mitigate N2O emissions in subtropical citrus orchards.

Size and polarity fractions of mobile organic matter from manure affect the sorption of sulfadiazine, caffeine and atenolol in soil

Waste-derived organics introduced to soils along with pharmaceutical active compounds (PhAC) are a crude mixture of compounds occurring in various size and polarity fractions. They affect the sorption of PhACs to soil; however, the relevant knowledge is still insufficient. The effects of different size and polarity fractions of manure-derived mobile organic matter (<63 µm) on the sorption of sulfadiazine, caffeine and atenolol to five topsoils were investigated. Mobilization of the PhACs was strongest in the presence of dissolved organic matter (mDOM, <0.45 µm), with a reduction of Kd of sulfadiazine, caffeine and atenolol by mean factors of 0.66, 0.57 and 0.41, respectively. The mobilizing effects of colloidal organic matter (0.45–10 µm) were slightly smaller. Fine particulate organic matter (10–63 µm) reduced the sorption of the PhACs in slightly acidic soils (pH 6.0), but increased it in strongly acidic soil (pH 4.3). Furthermore, hydrophobic (HO-mDOM) and hydrophilic (HI-mDOM) fractions of mDOM reduced the sorption capacity but increased the sorption nonlinearity of PhACs in soils. Effects of HO-mDOM and HI-mDOM were PhAC specific. It is suggested to consider the varying impacts of mobile fractions in animal manure and/or treated wastewater in evaluating the fate and environmental relevance of associated PhACs.

Assessment of Management Practices to Prevent Soil Degradation Threats on Lithuanian Acid Soils

An assessment of soil characteristics pertaining to their suitability for agricultural use in general is necessary to reverse the declining trend of soil quality and to ensure sustainable agriculture. The aim of this study was to determine the soil resistance (SRI) and degradation indices (SDI) under different agrotechniques and to find out whether management-induced changes are large enough to reduce soil degradation. The study was based on the comparison of physicochemical data of 3 long-term experiments conducted in the western part of Lithuania. Changes in soil properties over the past 20 years (1999–2019) have been determined. The most commonly used measures in Lithuania, such as soil liming, manuring, residue maintenance, and tillage, were selected for the analysis. The analysis carried out showed that the soil, which was fertilized with manure, had a higher value of soil quality parameters compared to natural Retisol: organic matter (by 0.53 percentage points), total nitrogen (by 0.04 percentage points), and the available amounts of phosphorus (by 69 mg/kg) and potassium (by 6.6 mg/kg). The assessment of the relative annual change in SOC content revealed that long-term soil manuring has significant SOC sequestration capability. Among the soil management techniques examined, it appeared that the greatest relative annual change (0.47 g kg−1yr−1) in SOC content was noted in manured soil. The results indicate that the higher degradation, and resistance values were observed in acid soil (pH 4.2), where liming was applied, indicating greater sensitivity to degradation. Based on analyzed indices, the agricultural practices ranked as: manuring &gt; residue management &gt; reduced tillage &gt; liming. The lowest SRI values were obtained for low level of nutrients (from −0.11 to 0.89), organic carbon (from −0.72 to −0.49), and pH (from −0.25 to –0.1), indicating that these properties are more sensitive to applied agricultural practices compared to others. All these findings provide information for promoting better soil management, soil protection, land use planning, and the planning of remedial measures, especially in the most afflicted areas.

Pengaruh Pemberian Kompos Campuran Ampas Tebu dan Kotoran Ayam terhadap Kesuburan Ultisol dan Hasil Produksi Kedelai (Glycine max (L.) merril)

Ultisol is a soil that contains low nutrients N, P and K and has the potential for Al-poisoning. Ultisol also has a low Cation Exchange Capacity, acidic soil pH and is sensitive to erosion. Improvements need to be made to increase Ultisol productivity, one of which is by adding organic ingredients. In addition to sugarcane bagasse compost, chicken manure contains many benefits because it contains a lot of organic materials that are good for the soil and plants. Increasing soybean yield is one of the priorities and can be done by utilizing Ultisol land. The purpose of this study is to determine the effect of composting a mixture of bagasse and chicken manure on ultisol fertility and soybean crop production. The research method carried out is experimental by conducting initial analysis of soil samples, compost application, maintenance, harvesting, soil analysis after compost application, calculation of height and crop yield. The results obtained were that the application of mixed compost of bagasse and chicken manure did not have a real effect on soil pH, P-available and Aldd, but could increase soil pH and P-available and lower Aldd in the soil. The application of mixed compost of bagasse and chicken manure was significantly different from plant height and was very different for soybean yield with the highest crop P3 (average plant height of 84.678 cm) and the highest yield of P3 3.938 tons/ha. The recommended treatment for soybean plants is P3 treatment with a dose of 15 tons/ha.

EVALUASI KESESUAIAN LAHAN UNTUK TANAMAN WORTEL (Daucus carota L.) DI KECAMATAN SIRAMPOG KABUPATEN BREBES JAWA TENGAH

The characteristics and quality of soil can affect the suitability of a land for a certain type of land use. The quality of the soil itself has a close relationship with the characteristics of the land because it has a score weight that affects the suitability of the land. Land characteristics such as slope and land cover affect soil quality such as nutrient content. Erosion calculations using the USLE method show that slope and land cover affect the rate of erosion, where erosion can leach nutrients that result in decreased soil quality. This study aims to determine the suitability of land for carrot plants in Sirampog District. Sirampog District has suitable marginal to suitable temperature, suitable humidity and rainfall, suitable soil texture (loam, sandy loam, and silty loam) relatively low cation exchange capacity (CEC) with very high base saturation, acidic soil pH, medium C-organic, medium N-total, very low P2O5 and very low K2O. This study provided an evaluation of land suitability so that farmers use effective and efficient techniques in cultivating carrot plants, so that carrot crop productivity can be optimal.

DURIAN STEM CANKER STATUS AND RELATIVE SOIL PROPERTIES IN PENINSULAR MALAYSIA

The arising stem canker issues can be devastating when new durian orchards are developed without proper disease management strategies. Hence, this study aims to obtain the current durian stem canker incident rates in Peninsular Malaysia including soil properties. 15 plots (2,500 m2 per plot) of durian orchards were evaluated and composite soil samples were analysed. Results showed that the greatest disease incidence (100%) was in old orchards (&gt; 10 years), with a severity of 63% whereas young orchards (&lt; 10 years) are at risk of severe stem canker with 71% of incidence and 43% of severity. There was a negative correlation (r = –0.220) between the incidence of stem canker and soil pH which indicated that durian trees grown in acidic soil (pH &lt; 5.0) were more prone to disease dispersion in the orchards. Moreover, severely infected trees were observed more in durian orchards with a higher proportion of finer sand particles in the soil (DI/ r = 0.199 &amp; DSI/r = 0.206) compared to coarse particles of clay and silt. Our work will play a crucial role in advancing real-time monitoring of durian stem cankers and enabling the prediction of potential disease outbreaks for the implementation of preventive measures.

Impact of Abiotic and Biotic Environmental Conditions on the Development and Infectivity of Entomopathogenic Nematodes in Agricultural Soils.

Many organisms, including beneficial entomopathogenic nematodes (EPNs), are commonly found in the soil environment. EPNs are used as biopesticides for pest control. They have many positive characteristics and are able to survive at sites of application for a long time, producing new generations of individuals. The occurrence of populations depends on many environmental parameters, such as temperature, moisture, soil texture, and pH. Extreme temperatures result in a decrease in the survival rate and infectivity of EPNs. Both high humidity and acidic soil pH reduce populations and disrupt the biological activity of EPNs. Nematodes are also exposed to anthropogenic agents, such as heavy metals, oil, gasoline, and even essential oils. These limit their ability to move in the soil, thereby reducing their chances of successfully finding a host. Commonly used fertilizers and chemical pesticides are also a challenge. They reduce the pathogenicity of EPNs and negatively affect their reproduction, which reduces the population size. Biotic factors also influence nematode biology. Fungi and competition limit the reproduction and survival of EPNs in the soil. Host availability enables survival and affects infectivity. Knowledge of the influence of environmental factors on the biology of EPNs will allow more effective use of the insecticidal capacity of these organisms.

Investigating the role of geochemistry and geotechnical properties in landslide characterization and triggering mechanisms: A case study from Dir Upper, Khyber Pakhtunkhwa Pakistan

The 83.5 km Chukyatan-Kumrat Upper Dir road plays a crucial role in transportation and tourism in North Pakistan. Despite its significance, the area faces frequent landslides due to hydrometeorological hazards, posing a threat to its stability. This study conducts the first extensive investigation of landslide susceptibility in the region, considering geological features, geotechnical properties, and rock weathering. The road traverses diverse rock formations, including meta-volcanics, andesites, meta-rhyolites, ignimbrites, volcanic ash, granodiorites, and spotted slates, overlain by residual soils. The presence of the Dir fault has led to significant accumulations of loose, weathered rock debris (>100 m deep). Exposed slopes exhibit polygonal stress fractures, joints, and fissures with steep inclinations (>40°), further enhancing instability. Geotechnical analysis reveals a low internal friction angle (28.5°–31.9°) and cohesion (4.1–5.9 kPa) of slope materials, indicating poor shear resistance compared to stable slopes. The unconfined compressive strength of bedrock (10.7–41.5 MPa) ranges from weak to moderate-strong, emphasizing the contribution of weaker rock formations to instability. Acidic soil pH (3.1–4.2) and clay minerals support the prevalence of weathering conditions promoting landslides. Thin section analysis and X-ray diffraction reveal hydrothermal alteration during low-grade metamorphism, leading to the formation of chlorite, smectite, montmorillonite, and zeolites. Additionally, physical weathering has increased quartz content, potentially impacting slope stability. The combined effect of factors such as steep slope geometry, low shear strength with strain-softening properties, rainfall, snowmelt, freeze-thaw activity, slope base cutting for road development, and massive loading from houses contributes to numerous landslides in the region. The study aids effective mitigation and preparedness in the Chukyatan-Kumrat area and offers insights for landslide susceptibility mapping in similar geological settings.

Use of organo-mineral amendments and Lupinus angustifolius to enhance mine tailings rehabilitation

Uncontrolled mine waste disposal globally poses severe environmental and health risks due to high concentrations of toxic substances like heavy metals and organic pollutants. This jeopardizes soil fertility and ecological balance. In this study, we adopted a novel approach based on the use of low-cost amendments that can be used in small to tailing sites for better plant growth and reducing health risks. On a 37-ha-old abandoned pyrrhotite mine site (Kettara) which was operated for 34 years near Marrakesh a high amount of tailing material low in organic C, high in salt contents, and contaminated by various heavy metals still exists. This material is low in fertility and is only patchily discovered by vegetation which should hinder the material of aeolian erosion. To increase the fertility of the material and improve vegetation growth, the soil material has to be improved by different organo-mineral amendments and their combinations as Marble waste (Mw), Clay (Cy), and Compost (Cp). To determine the impact of these amendments on plant growth the fast-growing Lupinus angustifolius L. a legume plant found close to the mining site, identified with the Regional Herbarium 'MARK' code: MARK-14861. This plant serves as a pivotal component in the comprehensive approach aimed at rehabilitating the soils surrounding the mining site. To identify the most effective organo-mineral amendment, we examined 65 combinations by mixing mine tailing soils with varying proportions (2.5%, 5%, 7.5%, or 10%) of the three distinct amendments and its combinations (Com), to identify the optimal rate for effective seeds germination and plant growth. Preliminary results on the germination index of L. angustifolius seeds revealed that four combinations (Com1: Cy2.5-Cp2.5-Mw10; Com2: Cy2.5-Cp5-Mw5; Com3: Cy7.5-Cp2.5-Mw7.5; and Com4: Cy10-Cp10-Mw10) maintained a high index due to improved soil properties. These combinations were used as the soil substrate material for a greenhouse experiment where plant growth, heavy metals accumulation, soil characteristics, and available metal content were determined. Our findings demonstrated that incorporating these four organo-mineral soil amendments into Kettara mine tailings led to a significant enhancement in plant growth. Notably, L. angustifolius plants exhibited a preferential accumulation of heavy metals in the root’s biomass (Cu: 565.60, Zn: 433.52, and Pb: 301.44 mg kg−1) with limited translocation to shoot parts (Cu: 37.44, Zn: 28.40, and Pb: 19.36 mg kg−1), particularly following the application of Com4. Furthermore, the properties of the mine soil were improved, including both neutralization of acidic soil pH (3 to ∼ 7) and reduction of metal elements bioavailability. Specifically, Com1, Com3, and Com4 effectively decreased the mobile fraction of metals in the tested mine tailings to exceptionally low levels achieving a reduction of 99% for copper, lead, and zinc, and 95% for arsenic. Our findings from this study indicated that our amendment holds promising potential for enhancing both plant growth and soil fertility, while simultaneously mitigating the mobility of heavy metals in heavy metal-contaminated acidic mine soils.

Entirely Biodegradable Wireless pH Sensor with Split‐Ring Resonators for Soil pH Monitoring

AbstractThis paper describes a wireless and battery‐free soil pH sensor made entirely of degradable materials. Soil pH monitoring is significant for precision agriculture and environmental conservation because soil health can be estimated by measuring soil pH. Soil pH can be measured by collecting soil samples and analyzing them in a laboratory environment or by inserting an electrode‐type sensor into the soil and measuring soil pH on site. However, neither method is suitable for wide‐area soil pH sensing for precision agriculture or environmental conservation. Herein, a fully biodegradable wireless pH sensor is presented that can be dispersed to outdoor environment to detect soil acidity. The sensor is operated wirelessly through split‐ring resonators (SRRs) that consist of patterned octacalcium phosphate (OCP)‐coated magnesium (Mg) on a poly‐lactic acid (PLA) sheet. At acidic soil pH, the degradation of each SRR results in a change in the electromagnetic response of the sensor. The operation of the sensor in six different types of acidic soils is demonstrated to distinguish the acidic soil wirelessly. It is expected that the biodegradable sensor can be applied to low‐cost, easy‐to‐use, and environmentally friendly monitoring of soil pH.

Selenobacteria-mediated Se transformation and uptake involving the unique genetic code.

Selenium (Se) is a crucial micronutrient for human health. Plants are the primary source of Se for humans. Selenium in the soil serves as the primary source of Se for plants. The soil contains high total Se content in large areas in Guangxi, China. However, the available Se is low, hindering Se uptake by plants. Microorganisms play a pivotal role in the activation of Se in the soil, thereby enhancing its uptake by plants. In this study, selenobacteria were isolated from Se-rich soils in Guangxi. Then two selenobacteria strains, YLB1-6 and YLB2-1, representing the highest (30,000 μg/mL) and lowest (10,000 μg/mL) Se tolerance levels among the Se-tolerant bacteria, were selected for subsequent analysis. Although the two selenobacteria exhibited distinct effects, they can significantly transform Se species, resulting in a decrease in the soil residual Se (RES-Se) content while concurrently increasing the available Se (AVA-Se) content. Selenobacteria also enhance the transformation of Se valencies, with a significant increase observed in soluble Se6+ (SOL-Se6+). Additionally, selenobacteria can elevate the pH of acidic soil. Selenobacteria also promote the uptake of Se into plants. After treatment with YLB1-6 and YLB2-1, the Se content in the aboveground part of Chinese flowering cabbage increased by 1.96 times and 1.77 times, respectively, while the Se accumulation in the aboveground part of the plant significantly increased by 104.36% and 81.69%, respectively, compared to the control. Further whole-genome sequencing revealed the genetic difference between the two selenobacteria. Additionally, 46 and 38 candidate genes related to selenium utilization were identified from YLB1-6 and YLB2-1, respectively. This work accelerates our understanding of the potential molecular mechanism of Se biofortification by selenobacteria. It also provides microorganisms and gene targets for improving crop varieties or microorganisms to exploit the rich Se source in soil.

Deciphering silver nanoparticles perturbation effects and risks for soil enzymes worldwide: Insights from machine learning and soil property integration

Globally extensive research into how silver nanoparticles (AgNPs) affect enzyme activity in soils with differing properties has been limited by cost-prohibitive sampling. In this study, customized machine learning (ML) was used to extract data patterns from complex research, with a hit rate of Random Forest > Multiple Imputation by Chained Equations > Decision Tree > K-Nearest Neighbors. Results showed that soil properties played a pivotal role in determining AgNPs’ effect on soil enzymes, with the order being pH > organic matter (OM) > soil texture ≈ cation exchange capacity (CEC). Notably, soil enzyme activity was more sensitive to AgNPs in acidic soil (pH < 5.5), while elevated OM content (>1.9 %) attenuated AgNPs toxicity. Compared to soil acidification, reducing soil OM content is more detrimental in exacerbating AgNPs’ toxicity and it emerged that clay particles were deemed effective in curbing their toxicity. Meanwhile sand particles played a very different role, and a sandy soil sample at > 40 % of the water holding capacity (WHC), amplified the toxicity of AgNPs. Perturbation mapping of how soil texture alters enzyme activity under AgNPs exposure was generated, where soils with sand (45–65 %), silt (< 22 %), and clay (35–55 %) exhibited even higher probability of positive effects of AgNPs. The average calculation results indicate the sandy clay loam (75.6 %), clay (74.8 %), silt clay (65.8 %), and sandy clay (55.9 %) texture soil demonstrate less AgNPs inhibition effect. The results herein advance the prediction of the effect of AgNPs on soil enzymes globally and determine the soil types that are more sensitive to AgNPs worldwide.

Identification of maize genotypes tolerance to acid soil stress using multiple criteria

This study aims to select maize hybrids that can tolerate acidic soil stress using several tolerance indexes. The research took place at two sites. Muneng Experimental Farm has average soil (pH=6.8), and Moncongloe Experimental Farm has acid soil (pH=5.8) from January to April 2023. A Randomized Complete Block Design (RCBD) was employed to organize ten maize hybrids, namely TH 1, TH 2, TH 3, TH 4, TH 5, TH 6, TH 7, TH 8, NK 6172, and P 32, each replicated three times. The variable observation was yield, standardized to 15% moisture content. To determine the tolerance of maize, six tolerance indexes were applied: The Stress Tolerant Index (STI), the Stress Susceptibility Index, the Mean Productivity (MP), the Harmonic Mean, the Stress Relative index (SI), and the Stress Susceptibility Percentage Index (SSPI). The result showed that hybrids that tolerate acidic soil are TH 1 and TH 2, as indicated by their average rating and standard deviation. In contrast, TH 5 and TH 7 hybrids are sensitive to acidic soil conditions. The STI and MP are suitable tolerant indexes that can select acid-tolerant hybrids with high yields under optimum and acidic conditions.

Mapping, impacts, characterization and extent of acid sulfate soils in Finland

Acid sulfate soils (ASS) cause big problems worldwide due to their potential to form sulfuric acid during oxidation of sulfidic materials, resulting in very acid soil (pH &lt;4.0). Impacts include acidification of soil and water, leaching of metals, decreased nutrient supply, deterioration of water fauna and flora, and corrosion of infrastructure. These soils also exhibit poor geotechnical properties. Finland has the largest occurrences of ASS in Europe, mainly along the coast of the Baltic Sea. The EU Water Framework Directive brought about wide co-operation to reduce the harmful impacts of ASS in Finland. One urgent step was to localize and characterize the occurrences of ASS. The more than 10 year-long programme, led by the Geological Survey of Finland (GTK), started in 2009 and field work was completed in 2021. During the programme observations, measurements, sampling and analyses were made at 23 000 sites in an area of 5 010 000 ha. Traditionally ASS in Finland have been considered to comprise fine-grained sulfidic sediments and/or their oxidized layers, occurring on agricultural land along the coast below the highest shoreline of the Littorina Sea transgression. This study recognized and classified significant occurrences of other types of potentially harmful ASS materials: (1) coarse-grained ASS (sand), (2) organic ASS (peat) and (3) unsorted ASS (till material). The methods, definition and classification of Finnish ASS have been revised. We calculated the extent of ASS along the coast to be about 1 000 000 ha corresponding to 21% of the area covered in the past by the Littorina Sea, and three to six times more than earlier estimates. In addition, some occurrences of ASS were recognized inland, mainly related to black shales and sulfidic ores. The mapping data can be accessed via the GTK map service (www.gtk.fi) providing information about the distribution and properties of ASS.

Institutionalization of integrated pest management in the food estate development area, Sungai Mandau Subdistrict, Siak Regency, Riau

The food estate program aims to enhance national food production, regional development, food security, and the welfare of farmers. Sungai Mandau, a peatland area in Siak Regency, was opened in 2010 as a food estate for rice cultivation to meet the rice demand in Riau Province. However, peatland development for agriculture faces challenges such as low soil fertility, acidic soil pH, and nutrient deficiencies. This research aims to study the agronomic factors, land suitability, pest management, and agricultural institutions in the context of food estate development in Sungai Mandau. This study starts from August 2022 to April 2023. The method was in-depth interviews with fifty farmers to capture the condition of the Sungai Mandau food estate. Additionally, field observations were conducted on land, soil conditions, pests and diseases. The land condition of the Sungai Mandau food estate falls into suitability class S3 (the lowest suitability) for rice cultivation. Farmers' pest management practices are far from the Integrated Pest Management (IPM) concept. The cultivation practices do not fully support IPM and are not in line with the land conditions. The lack of farmer knowledge is attributed to the ineffective roles of field agricultural extension officer (FAEO) and agriculture technopark (ATP), who should play a significant and close role with the farmers. Information dissemination at the cooperative and farmer group levels has not been effective for a long time. Non-Governmental Organizations (NGOs) play a role in institutionalizing IPM, and this institutionalization can occur when all institutions and stakeholders actively participate.