Plant Availability Research Articles

Forecasting interannual abundance of Helicoverpa zea (Lepidoptera: Noctuidae).

Corn earworm, Helicoverpa zea Boddie (Lepidoptera: Noctuidae), is a common herbivore that causes economic damage to agronomic and specialty crops across North America. The interannual abundance of H. zea is closely linked to climactic variables that influence overwintering survival, as well as within-season host plant availability that drives generational population increases. Although the abiotic and biotic drivers of H. zea populations have been well documented, prior temporal H. zea modeling studies have largely focused on mechanistic/simulation approaches, long term distribution characterization, or degree day-based phenology within the growing season. While these modeling approaches provide insight into H. zea population ecology, growers remain interested in approaches that forecast the interannual magnitude of moth flights which is a key knowledge gap limiting early warning before crops are planted. Our study used trap data from 48 site-by-year combinations distributed across North Carolina between 2008 and 2021 to forecast H. zea abundance in advance of the growing season. To do this, meteorological data from weather stations were combined with crop and soil data to create predictor variables for a random forest H. zea forecasting model. Overall model performance was strong (R2 = 0.92, RMSE = 350) and demonstrates a first step toward development of contemporary model-based forecasting tools that enable proactive approaches in support of integrated pest management plans. Similar methods could be applied at a larger spatial extent by leveraging national gridded climate and crop data paired with trap counts to expand forecasting models throughout the H. zea overwintering range.

Greening up the City with Native Species: Challenges and Solutions

Urban green spaces provide many benefits, including to human wellbeing, ecosystem services, and urban wildlife. Thus, there are many reasons to green up urban spaces, especially by using native species. Furthermore, urban green spaces are suited to enhancing biodiversity without negatively impacting food or fiber production. Municipalities and private landowners invest substantially in landscaping and its maintenance. However, much of that outlay supports non-native plants that may be less adapted to local conditions such as rainfall patterns and temperature ranges, thus having greater resource requirements, as well as being less supportive of native wildlife and possessing a greater potential of becoming invasive. Here, we explore ways to increase the use of native plant species in urban settings to reduce the need for watering or chemical application, enhance the support of native species, and reduce the risk of invasion to urban and ex-urban habitats. We identify three main impediments: the perception of native species as less aesthetically pleasing, the availability of native plants in the nursery industry, and the willingness of policymakers to take supportive measures. We propose methods to address all three, providing successful examples from a number of US localities and a case study that demonstrates what drivers might exist and what actions remain to be taken.

Planning Design of Artificial Lift Hydraulic Jet Pump at Suspend Well in PT Pertamina EP Field

Artificial lift aims to assist in lifting fluid from the bottom of the well (reservoir) to the surface. Well-X is a suspended well planned to be reactivated using an artificial lift suitable for further production operations. The water injection plant's availability as a power fluid supply makes the hydraulic jet pump an efficient artificial lift that can be operated on wells in this field. Hydraulic Jet Pump design planning requires well data, reservoir data, production data, fluid characteristic data, and Pressure, Volume, and Temperature for calculations with quantitative methods. The surface injection pressure parameter is subjected to sensitivity analysis to obtain the production rate that can be optimally produced under the Inflow Performance Relationship. The results of the study show that the surface injection pressure in the range of 500-800 psi does not intersect with the Inflow Performance Relationship Figure.

Influence of Nano Urea on Growth Yield and Nutrient Uptake of Blackgram

Background: There is no doubt that the enormous increase in global food production is a direct result of greater use of inorganic fertilizers. However, a number of research studies indicate that the rising use of conventional fertilizers has resulted in major environmental risks, including soil and water body contamination. Nanotechnology and nano-fertilizers have recently been used in agriculture to create healthier solutions. Therefore, there is a pressing need to improve the N availability for plants, while reducing its harmful effects to the soil and environment. Methods: Keeping this point of view, the pot culture experiment was carried out to study the “Impact of nano-urea (Liquid) on blackgram (VBN 8) (Vigna mungo L.) Productivity” with an objective of study the influence of Nano-Urea on growth and yield attributes of Blackgram. The experiment was conducted at Vanavarayar Institute of Agriculture, Pollachi during the Kharif (June-September) season of 2022 and 2023. The treatment includes application of various level of nano urea (1.25 litres ha-1) as foliar spray and soil application along with recommended dose of P and K in comparison with RDF and control (without any nutrient). The treatments were replicated three times in a completely randomized block design. Result: Among the different treatment combination, application of nano-urea (Liquid) 1.25 litres ha-1 as Foliar Spray (FS) (IFFCO) + P and K RDF (T2) resulted in higher pod weight (4.1 and 6.2 g plant-1) and seed weight (3.2 and 3.6 g plant-1) in 2022 and 2023, respectively. Application of nano-urea (Liquid) 1.25 litres ha-1 as Foliar Spray (FS) + PandK RDF responded equally with RDF + Urea 1% foliar spray on better growth and development of blackgram. At the critical juncture, adequate nitrogen from nano-urea would have ensured a steady supply of nitrogen, stimulating meristematic activity and cell elongation in plants and improving the crop performance.

Critical care services in Bagmati province of Nepal: A cross sectional survey

Background This study aimed to assess the current status of critical care services in 13 districts of Bagmati Province in Nepal, with a focus on access, infrastructure, human resources, and intensive care unit (ICU) services. Methods A cross-sectional survey was conducted among healthcare workers employed in 87 hospitals having medical/surgical ICUs across Bagmati Province. Data were collected through structured questionnaires administered via face-to-face and telephone survey. Descriptive analysis was used for data analysis, involving frequencies and percentages. Results From 87 hospitals, a total of 123 ICUs were identified in the province, providing 1167 beds and 615 functioning ventilators. The average ICU bed availability per 100,000 population was 19, ranging from 3.6 in Makwanpur to 33.9 in Kathmandu. Out of 13 districts, 95% of beds were concentrated in just four districts, while six had no ICU facilities. Of the available facilities, 69.9% were owned by private entities. One-to-one nurse-to-ventilated bed ratio was maintained by 63.4% of ICUs during daytime, and 62.6% at nighttime. Furthermore, 74.8% of ICUs had consultants trained in critical care medicine. While essential equipment availability was higher in Bagmati province, gaps existed in the availability of oxygen plants and isolation rooms. Similarly, many ICUs offered continuous medical education and cardiopulmonary resuscitation (CPR) training, but improvements were necessary in clinical audits, antibiotic stewardship programs, and research engagement. Conclusions Disparities in critical care resources were evident across districts in Bagmati Province, highlighting the need for a balanced and decentralized approach to ensure equitable access to care. Although there were disparities, numerous ICUs were effectively carrying out multiple critical care procedures. This study suggests conducting a nationwide mapping of ICU resources, prioritizing infrastructure development, optimizing resource allocation, and establishing national protocols.

Annotated Checklist of Poroid Hymenochaetoid Fungi in Central Asia: Taxonomic Diversity, Ecological Roles, and Potential Distribution Patterns.

Central Asia, located at the heart of Eurasia, is renowned for its varied climate and vertical vegetative distribution, which support diverse biomes and position it as a global biodiversity hotspot. Despite this ecological richness, Central Asia's fungal diversity, particularly wood-inhabiting macrofungi, remains largely unexplored. This study investigates the diversity, ecological roles, and potential distribution of poroid Hymenochaetoid fungi in the region. By conducting field surveys, collecting basidiomes, and reviewing the literature and herbarium records from five Central Asian countries, we compiled a comprehensive checklist of these fungi. In total, 43 Hymenochaetoid species belonging to 18 genera were identified, with Inonotus, Phellinus, and Phylloporia being the most species-rich. Notably, Inonotus hispidus and Phellinus igniarius were found to be the most widespread species. These macrofungi play essential ecological roles as saprotrophs and pathogens of various identified host plant families, aiding in lignin degradation and exhibiting diverse enzymatic activities. For the first time, we modelled the potential distribution patterns of Hymenochaetoid fungi in Central Asia, revealing that their distribution is strongly influenced by host plant availability and temperature-related factors. The three most critical variables were host plant density, annual temperature range (Bio7), and mean temperature of the warmest quarter (Bio10). The distribution of suitable habitats is uneven, with highly suitable areas (4.52%) concentrated in the mountainous border regions between Kazakhstan, Kyrgyzstan, Tajikistan, and Uzbekistan. These results underscore the significance of specific environmental conditions for the growth and survival of Hymenochaetoid fungi in this region. Our findings highlight the urgent need for continued mycological and host plant research and expanded conservation initiatives to document and preserve macrofungal and botanical biodiversity in this under-explored area. In light of climate change, the collected mycological and botanical data provide a valuable reference for promoting forest health management globally.

Effects of maternal condition, disease status, and behavior on survival of juvenile bighorn sheep

AbstractNutrition integrates and interacts with a variety of biotic and abiotic factors that modulate performance of large‐herbivore populations. Accordingly, studying patterns of herbivore performance through the lens of nutrition can shed light on the complex mechanisms that drive population dynamics. We studied bighorn sheep (Ovis canadensis) and their habitat and quantified relationships among 1) the foodscape (defined herein as spatiotemporal variation in the quality and availability of forage plants); 2) female behavior (i.e., use of the foodscape and rugged escape terrain), condition (% ingesta‐free body fat), and disease status (infection status and antibody levels); and 3) juvenile survival. We conducted intensive vegetation sampling and used generalized additive modeling to map the foodscapes available to bighorn sheep during summer (May–September) over 2 years in 2 population ranges in Idaho, USA: the East Fork of the Salmon River and the Lost River Range. In each study area, we used global positioning system (GPS) collars and field observations to monitor adult female behavior and lamb survival, quantified nutritional condition and disease status of maternal females in late winter, and used known‐fate survival modeling to test for effects of female traits and behavior on lamb survival. Adjusted R2 values for foodscape models ranged from 0.34 to 0.61. Collared females consistently selected rugged escape terrain in both study areas, but we found little evidence of selection for the foodscape. We did not detect any consistent effects of maternal space‐use behavior on lamb survival. In contrast, nutritional condition of females in late winter had a strong, positive effect on summer lamb survival: lambs born to females in relatively good condition (15% ingesta‐free body fat, ~94% probability of lamb survival) were roughly 4 times more likely to survive the summer months than lambs born to females in poor condition (5% ingesta‐free body fat, ~25% probability of lamb survival). In addition, whereas maternal infection with the pathogen Mycoplasma ovipneumoniae had no discernable effect on juvenile survival, lambs born to females that showed no sign of exposure (antibody) to M. ovipneumoniae (~99% probability of survival) were roughly 3 times more likely to survive the summer than lambs born to females that had mounted a strong immune response (35% probability of survival). Our work adds to a growing body of literature linking nutritional condition to juvenile survival and other key vital rates, and highlights the importance of efforts to better understand the role of nutrition in the context of disease and other factors limiting performance of herbivore populations.

Application of Rice Straw and Corn Straw Compost for Enhancing Phosphorus Availability in Ultisol and Corn Plants

Application of Rice Straw and Corn Straw Compost for Enhancing Phosphorus Availability in Ultisol and Corn Plants

Mineral nitrogen availability from co‐digested biodigester products as affected by feedstock pretreatment

AbstractDigestion of animal manures with crop residues to produce methane (CH4) gas is a promising technique to generate “green” energy from agricultural wastes while producing biofertilizers. This study was conducted to understand nitrogen (N) release by biofertilizers from the products of solid‐state anaerobic digestion of untreated corn stover and stover treated with aqueous ammonia (NH4OH), calcium hydroxide (Ca(OH)2), or Ca(OH)2 plus Fe3O4 nanoparticles blended with dairy manure. Eight biofertilizer materials (feedstocks and digestates) from anaerobic digestion were incubated in the lab for 28 days and the NH4–N and NO3–N data obtained were used to predict N release for seasonal plant availability. Of the untreated and alkaline pretreated biofertilizer materials examined, only calcium hydroxide‐pretreated digestate (CaD) had greater N release (220 mg kg−1) than the untreated soil control (155 mg kg−1) after 28 days of incubation time. In addition, CaD had the most rapid N release rate (0.16 mg kg−1 day−1) and shortest lag phase time (41 days) with a predicted mineral N release of 777 mg kg−1 at 120 days. However, including Fe3O4 nanoparticles slightly suppressed N release. Thus, applying calcium hydroxide‐pretreated digestate to soil could complement N supply for crop cultivation as facilitated by the initial carbon to nitrogen (C/N) ratio, despite slight N immobilization when iron nanoparticles were added.

Critical care services in Bagmati province of Nepal: A cross sectional survey.

This study aimed to assess the current status of critical care services in 13 districts of Bagmati Province in Nepal, with a focus on access, infrastructure, human resources, and intensive care unit (ICU) services. A cross-sectional survey was conducted among healthcare workers employed in 87 hospitals having medical/surgical ICUs across Bagmati Province. Data were collected through structured questionnaires administered via face-to-face and telephone interviews. Descriptive analysis was used for data analysis, involving frequencies and percentages. From 87 hospitals, a total of 123 ICUs were identified in the province, providing 1167 beds and 615 functioning ventilators. The average ICU bed availability per 100,000 population was 19, ranging from 3.6 in Makwanpur to 33.9 in Kathmandu. Out of 13 districts, 95% of beds were concentrated in just four districts, while six had no ICU facilities. Of the available facilities, 69.9% were owned by private entities. One-to-one nurse-to-ventilated bed ratio was maintained by 63.4% of ICUs during daytime, and 62.6% at nighttime. Furthermore, 74.8% of ICUs had consultants trained in critical care medicine. While essential equipment availability was higher in Bagmati province, gaps existed in the availability of oxygen plants and isolation rooms. Similarly, many ICUs offered continuous medical education and cardiopulmonary resuscitation (CPR) training, but improvements were necessary in clinical audits, antibiotic stewardship programs, and research engagement. Disparities in critical care resources were evident across districts in Bagmati Province, highlighting the need for a balanced and decentralized approach to ensure equitable access to care. Although there were disparities, numerous ICUs were effectively carrying out multiple critical care procedures. This study suggests conducting a nationwide mapping of ICU resources, prioritizing infrastructure development, optimizing resource allocation, and establishing national protocols.

Insect Pollinator Voucher Collection: Pollinator Visitation to Pacific Northwest Native Plants and Native Cultivars

Planting native flora continues to grow in popularity as a means of conserving pollinator fauna in fragmented landscapes. Due to the limited availability of native plants, consumers may encounter cultivars in their search for plants native to their region. Though consumers have a documented interest in planting native flora for their purported benefits to pollinators, it is unclear whether cultivars provide the same benefits as wild-type native plants. Over three years (2020-2022), we observed and collected pollinators from a common garden experiment in Corvallis, OR containing 8 species of Pacific Northwest native plants, 18 cultivars derived from native plant species, and one exotic perennial plant. Methods for collection are described in further detail in Hayes et al. (in prep.). Here, we report on and document the deposition of taxonomic voucher specimens which represent the primary species concepts used throughout Hayes et al. (in prep.) (Accession #). Specimens were identified to the lowest possible taxonomic level by L. R. Best (bees, Hymenoptera: Apoidea) and J. J-M. Hayes (syrphid flies, Diptera: Syrphidae). The vouchered material includes 139 individual specimens with at least one representative per caste and sex, as available, of 55 species and 14 morphospecies of bees (Hymenoptera: Apoidea) and 13 species and one morphospecies of syrphid flies (Diptera: Syrphidae). Additional vouchers are included for specimens identified only to the morphospecies level, and Megachile brevis Say, 1837 individuals that were captured while collecting sections of petal from Clarkia amoena (Lehm.) A.Nelson & J.F.Macbr. plants. These 139 voucher specimens come from a much larger dataset, containing over 6,500 observational records of plant-pollinator interactions.

Insect Pollinator Voucher Collection: Pollinator Visitation to Pacific Northwest Native Plants and Native Cultivars

Planting native flora continues to grow in popularity as a means of conserving pollinator fauna in fragmented landscapes. Due to the limited availability of native plants, consumers may encounter cultivars in their search for plants native to their region. Though consumers have a documented interest in planting native flora for their purported benefits to pollinators, it is unclear whether cultivars provide the same benefits as wild-type native plants. Over three years (2020-2022), we observed and collected pollinators from a common garden experiment in Corvallis, OR containing 8 species of Pacific Northwest native plants, 18 cultivars derived from native plant species, and one exotic perennial plant. Methods for collection are described in further detail in Hayes et al. (in prep.). Here, we report on and document the deposition of taxonomic voucher specimens which represent the primary species concepts used throughout Hayes et al. (in prep.) (Accession #). Specimens were identified to the lowest possible taxonomic level by L. R. Best (bees, Hymenoptera: Apoidea) and J. J-M. Hayes (syrphid flies, Diptera: Syrphidae). The vouchered material includes 139 individual specimens with at least one representative per caste and sex, as available, of 55 species and 14 morphospecies of bees (Hymenoptera: Apoidea) and 13 species and one morphospecies of syrphid flies (Diptera: Syrphidae). Additional vouchers are included for specimens identified only to the morphospecies level, and Megachile brevis Say, 1837 individuals that were captured while collecting sections of petal from Clarkia amoena (Lehm.) A.Nelson & J.F.Macbr. plants. These 139 voucher specimens come from a much larger dataset, containing over 6,500 observational records of plant-pollinator interactions.

Influence of ecological characteristics and phylogeny on native plant species' commercial availability.

Plant vendors generate a commercial species pool, the subset of species in a regional flora that is purchasable. The availability of plant species from commercial vendors can influence the composition and outcomes of conservation, landscaping, and restoration plantings. Although previous research suggests that most plant species are unavailable, there is little information that identifies the plant characteristics associated with commercial availability. We studied the composition of the commercial species pool by examining the ecology, phylogeny, and phenology of a regional flora in the Midwestern United States. We used a database of native plant species sold by 557 vendors throughout the Midwest (USA) to characterize species' availability. We compiled ecological characteristics of all plant species, including range size, growth form, moisture requirements, and conservatism-meaning fidelity to high-quality natural areas. We characterized phenological (bloom time) data for a subset of the regional flora. Finally, we constructed a regional phylogeny to assess the phylogenetic signal of plant availability. We expected that commercially unavailable species would be niche specialists or short-lived (often nonconservative "weedy") species, and that they would bloom earlier in the season and for a shorter time. We found that commercially available species were more long-lived, had larger range sizes, had intermediate fidelities to wetlands and high-quality or disturbed natural areas, and were associated with certain plant types, especially shrubs and trees. In contrast, ferns and graminoids were underrepresented in the commercial trade. There was a strong phylogenetic signal associated with commercial availability; some plant families had nearly all or none of their species commercially available. Example families with low representation included Orchidaceae, Potamogetonaceae, Cyperaceae, and fern families. Longer bloomed species were more commercially available, but we did not find differences in availability between early- and late-blooming species. Despite the diversity of the commercial pool in the Midwest, it is an unrepresentative, nonrandom subset of the regional species pool. This finding may promote the mismatch in species diversity and composition between remnant natural habitats and restorations because many specialized species are commercially unavailable to conservation and restoration practitioners. We encourage strategies to promote the availability of underrepresented plant diversity in the commercial species pool.

Intraspecies variation in mycorrhizal response of Medicago sativa to Rhizophagus irregularis under abiotic stress.

Plant partnerships with arbuscular mycorrhizal fungi (AMF) improve plant resilience to stress by increasing the plant's access to and uptake of essential nutrients and water, as well as regulating the plant's stress response. The magnitude and direction of AMF effects during the relationship depend on multiple factors including plant identity and environmental context. To investigate how AMF influence plant responses to environmental stresses, we assessed the effects of drought and salinity on growth, final biomass, and reproduction of nine alfalfa (Medicago sativa) cultivars inoculated with Rhizophagus irregularis or grown alone. In absence of stress, the fungus increased nutrient content, but caused declines in biomass through a reduction in initial growth that was not overcome by a later growth spurt. Mycorrhizal fungus inoculation also magnified stress effects on growth in most scenarios, but this depended on the stress type and cultivar. For salinity, this stress increase in inoculated plants was mediated by increased salt accumulation. Flowering of each cultivar was affected by both inoculation and stress type, albeit erratically, whereas seed production was only affected by inoculation when drought stressed. We found no clear pattern distinguishing differences in mycorrhizal fungus effects on stress among cultivars; however, our results show that mycorrhizal fungus effects on plant stress responses are contingent on the plant performance metric and stress type, highlighting the complexity of responses to mycorrhizas.

Seasonal dynamics of forage nutrition in smallholder goat production systems in Malawi

Forage and browse are a valuable natural resource in Malawi that can be used to support livestock production which, in turn, can contribute towards delivering income and nutrition to households and communities. However, the quality and quantity of forages can be poor, especially during the dry season. The objective of this study was to assess the nutritional composition of naturally available forages across smallholder livestock systems in Malawi, with particular focus on seasonal differences in quality and quantity. Samples of herbaceous forages and browse were collected over 17 months, across four sites (30 farms/smallholders) in central Malawi. Forages underwent nutritional analysis for crude protein, fibre and ash/organic matter. NDVI obtained from satellite imagery was used as a proxy for forage availability. Forage nutrition and availability were most adequate in the wet season, with higher concentrations of crude protein and a greater availability of herbaceous plants. There were significant differences in low-digestibility fibre fractions between locations, likely due to local factors such as soil and hydrology. The fall in crude protein concentrations from the wet season to the dry season along with a reduction in forage biomass represents a seasonal nutritional feed gap that may impact productivity within livestock systems.

Differences in plant availability of phosphorus and potassium in pelletized and granulated biochar for an Andisol

AbstractBiochar will be broken into tiny pieces for processes of production, transportation, and application, which causes dust emissions for those processes. Particulate matter (PM) released from biochar may have negative effects on human health and increase the atmospheric burden of shortwave absorbing black carbon aerosols. Pelletizing feedstock before the thermochemical conversion is expected to reduce the emission of PM in the processing and post-processing phases. Effects of application of pelletized biochar, produced from broiler manure at different pyrolysis temperatures, into an Andisol on soil physicochemical properties and crop yields have been investigated in this study. Effects of pelletizing and pyrolysis temperatures (400, 600, and 800 °C) on dissolution properties and soil physicochemical properties were completely different between phosphorus and potassium. Pelletized broiler manure–derived biochar can be used as fast-release potassium fertilizer regardless of pyrolysis temperatures. In contrast, the extraction pattern of phosphorus contained in the biochar significantly differed by pelletizing and pyrolysis temperatures. Plant dry yields and phosphorus uptakes in soils amended with granulated broiler manure-derived biochar were significantly higher than those in soils amended with pelletized broiler manure-derived biochar (e.g., 3.4 times larger in 800 °C). This result suggests that the breakdown of pelletized biochar into granulated biochar could improve interaction between phosphorus contained in biochar and roots. Pelletized biochar will be transformed into granulated biochar through the freeze–thaw cycle, dry–wet cycle, and rotary tillage over the long term. Therefore, pelletized biochar derived from broiler manure at higher pyrolysis temperatures can be novel phosphorus-supplying amendments over the long term. Graphical abstract

Improving the power production of Mutriku Wave Power Plant throughout tuning the actual generator and damping valve limits

The Mutriku Wave Power Plant (MWPP) has successfully operated since 2011, demonstrating remarkable operational stability with minimal issues of OWC technology in breakwaters. So far, the design, selection, and operation ranges of the generators at MWPP prioritized reliability. However, once the viability of the technology has been demonstrated, it is important to explore ways to increase energy production with the current design of the technology.The objective of the present work is to improve the power production in MWPP throughout the Power take-off (PTO), increasing the operational limits of the generator and of the damping valve, which is located between the air chamber and the turbine. To this aim, new sensors have been installed in the plant, such as an inlet pressure sensor, to characterise the behaviour of the PTO. Investigations into the power produced and the plant availability have concluded that modifying control laws of the current configuration could help to increase power production under generator thermal operation ranges.The numerical results presented in the paper demonstrate that the potential benefit to the overall energy production of the MWPP could be significant, leading to greater advancements in the feasibility of wave energy technologies. The analysis of changes and improvements into the MWPP control strategies will provide further guidance into the development of novel wave energy control systems and components for future testing.

Soil phosphorus compared to nitrogen limitation increases the uncertainty of subsoil organic carbon sequestration in Pinus massoniana mixed forests

Limited nitrogen (N) and phosphorus (P) availability will constrain terrestrial carbon sinks in the 21st century. Mixed forests improve the plant community composition and productivity of pure coniferous forests. Nevertheless, it is uncertain whether and to what extent changes in soil N and P dynamics caused by mixed forests can affect forest soil organic carbon (SOC) stocks. The research purpose is to demonstrate and evaluate the effects of soil N and P on SOC stocks in Pinus massoniana mixed forests. Our meta-analysis, which included 616 paired observations, revealed that the coupling of soil N, P, and plant species richness (PSR) contributed 22.6%, 28.8%, and 28.4%, respectively, to SOC stock accumulation in the topsoil (0–20 cm), subsoil (20–100 cm), and whole profile (0–100 cm). The interactions between soil total N and P concentrations (TN:TP ratios) dominated the increase in SOC stocks in the mixed forest topsoil and whole profile, explaining 35.6% and 20.3% of the variation, respectively. Conversely, independent TN and TP concentrations were the primary contributors (explained by 17.5% and 12.3%, respectively) to subsoil SOC stocks increase. The TN and TP concentrations limit SOC stock accumulation in mixed forests for the next 60 years (2025–2085), with the TP concentration and TN:TP ratio having a greater effect in subsoil. Fortunately, the TN and TP limitations on SOC stock increase in mixed forests can be mitigated and balanced by altering soil TN:TP ratio by increasing or decreasing the PSR (PSR thresholds for topsoil, subsoil, and whole profile were 15, 8, and 8, respectively). Overall, plant mixing fails to enhance plant availability of pure forest soil N and P. Accelerated N cycling and increased P reabsorption efficiency are optimal strategies for balancing N and P supply in mixed forests, promoting biomass accumulation, and ensuring SOC stocks increase.

Isolasi dan Karakterisasi Bakteri Rhizobium asal Bintil Akar Tanaman Kacang Tanah (Arachis hypogaea) dan Koro Rawe (Mucuna bracteata)

Nitrogen (N) is naturally available in the form of N2. Nitrogen fixation can be facilitated by microbes such as Rhizobium bacteria, which can establish symbiosis with the roots of legume plants to form root nodules that perform nitrogen fixation. This study aims to determine the characteristics of Rhizobium bacteria in the root nodules of peanuts (Arachis hypogaea) and koro rawe (Mucuna bracteata). The methods used in this research include collecting root nodules, isolating Rhizobium bacteria, and identifying and characterizing these bacteria for their nitrogen fixation and phosphate solubilization capabilities. Characterization results on YEMA + Congo red media indicated that 10 out of 16 isolates from peanut root nodules and 30 out of 55 isolates from koro rawe root nodules were positive for Rhizobium bacteria. The nitrogen fixation activity test revealed that only 4 isolates from peanut root nodules and 6 from koro rawe root nodules exhibited nitrogen fixation ability in Jensen's medium. The highest phosphate solubilization index was obtained from isolate KK.5.1.1 (0.5±0.08), while the lowest was from isolate KK.5.2.2 (0.09±0.06). This research underscores the significance of Rhizobium in enhancing nitrogen availability and phosphate solubilization for legume plants.

Immobilization of Heavy Metals in Biochar Derived from Biosolids: Effect of Temperature and Carrier Gas

Slow pyrolysis was carried out in biosolids under three different temperatures (400, 500 and 600 °C) and two different carrier gases (CO2 and N2) on a fluidized bed reactor. The total concentration, chemical fractionation, and plant availability of the heavy metals in biochar were assessed by standard methods. The total concentration of Fe, Zn, Cu, Mn, Cr, Ni and Pb increased with the conversion of biosolids to biochar and with increasing pyrolysis temperature. The community’s Bureau of Reference (BCR) sequential extraction identified the migration of metals from toxic and bioavailable to potentially stable available or non-available forms at higher pyrolysis temperatures. Diethylenetriamine penta-acetic acid (DTPA)-extractable metals (Cu, Zn, Cd, Cu, Fe and Pb) were significantly lower in biochar compared to biosolids. By replacing N2 with CO2, the total metal concentration of heavy metals was significantly different for Mn, Ni, Cd, Pb and As. There were larger amounts of metals in the residual and oxidizable fractions compared to when N2 was used as a carrier gas. Consequently, the biochar produced at higher temperatures (500 and 600 °C) in the N2 environment exhibited lower potential ecological risks than in CO2 environments (69.94 and 52.16, respectively, compared to values from 75.95 to 151.38 for biochars prepared in N2). Overall, the results suggest that the higher temperature biochar can support obtaining environmentally safe biochar and can be effective in attenuating the ecological risks of biosolids.