Increased Nutrient Concentrations Research Articles

Phosphorus Fertilization and Chemical Root Pruning: Effects on Root Traits During the Nursery Stage in Two Mediterranean Species from Central Chile

The role of a plant root system in resource acquisition is relevant to confront drought events caused by climate change. Accordingly, nursery practices like phosphorous (P) fertilization and root pruning have been shown to modify root architecture; however, their combined benefits require further investigation in Mediterranean species. We evaluated the effect of applied P concentrations (0, 15, 60, and 120 mg L−1 P) with or without chemical (copper) root pruning (WCu, WoCu, respectively) in Aristotelia chilensis and Quillaja saponaria on morpho-physiological and root architecture traits. Higher P concentration increased nutrient content in both species concurrent with higher growth. In A. chilensis, higher P concentrations only increased the length and volume of medium roots. In Q. saponaria, P additions increased root length and diameter and the length and volume of fine and medium roots. The root-to-shoot ratio declined with WCu in A. chilensis (23.1%) and Q. saponaria (15.7%). Unlike our hypothesis, fine root architecture remained unaffected with root pruning in A. chilensis, while fine root length and volume decreased with increasing P concentrations in Q. saponaria. Thus, P fertilization enhances root development more consistently than root pruning, highlighting the need for further testing under water deficit conditions to optimize nursery practices.

Multiple stressor effects act primarily on microbial leaf decomposers in stream mesocosms.

At the global level, stream ecosystems are influenced by multiple anthropogenic stressors such as eutrophication, habitat deterioration, and water scarcity. Multiple stressor effects on stream biodiversity are well documented, but multiple stressor effects on stream ecosystem processes have received only limited attention. We conducted one mesocosm (stream channel) and one microcosm (feeding trial) experiment to study how combinations of reduced flow, increased nutrient concentrations, and increased fine sediment coverage would influence fungal and macroinvertebrate decomposer assemblages and their active contribution to leaf decomposition. In the stream channels, increased fine sediment coverage significantly reduced fungal biomass, occurrence frequencies of most aquatic hyphomycete species, and microbial leaf decomposition rates compared to untreated controls. Macroinvertebrate-induced leaf decomposition rates were mainly correlated to total fungal biomass and community composition. Neither increased nutrient concentrations, nor reduced flow conditions significantly influenced leaf decomposer communities or decomposition rates. The feeding trials revealed significantly reduced leaf consumption in the freshwater amphipod Gammarus pulex when feeding on leaf material from treatments with increased fine sediment coverage in the mesocosm experiment. When offered a food choice between sterile, unconditioned leaf material and leaf material from treatments with increased fine sediment coverage, G. pulex foraged mainly on sterile material. This study showed that increased fine sediment coverage can alter the flux of energy and material in the detrital food chain through bottom-up regulation of leaf conditioning by fungal decomposers. Our results suggest that increasing attention should be given to mitigating fine sediment transport and deposition in stream systems to preserve ecosystem functioning within the detrital food chain.

Contrasting Effects of Increasing Invasive Crayfish Densities on Competing Submerged Macrophytes in Shallow Lakes

ABSTRACT Non‐native crayfish are among the most widespread aquatic invasive species worldwide. High densities of crayfish in lakes can potentially cause complete loss of macrophytes through herbivory, physical destruction, shading by suspension of sediments and nutrient release facilitating phytoplankton, thus altering ecosystem state and functions. However, lower crayfish densities may affect different macrophyte species in different ways, thus altering competition between macrophyte species with different growth forms. We hypothesize that high crayfish densities can completely destroy submerged macrophyte communities and shift systems into more turbid conditions whereas low crayfish densities can promote low‐growing macrophytes that compete with canopy‐forming species. To test these hypotheses, we applied three different densities (2, 4, 8 crayfish m−2) of the invasive crayfish Procambarus clarkii and a control (no crayfish) to 36 mesocosms of monocultures and mixed stands of low‐growing and canopy‐forming submerged macrophytes for 60 days. We measured concentrations of nutrients, suspended solids, phytoplankton and periphyton and above‐ and belowground biomass of low‐growing Vallisneria natans and canopy‐forming Hydrilla verticillata. In addition, we conducted a meta‐analysis of crayfish impacts on macrophytes to compare effect sizes between different crayfish densities. Using data from published studies, we derived the relationship between crayfish density and crayfish‐induced reductions in macrophyte abundance. Our meta‐analysis revealed a significant decline of macrophytes with increasing crayfish densities. In line with existing studies, high crayfish densities caused a strong loss of both low‐growing and canopy‐forming macrophytes and increased nutrient concentrations, phytoplankton biomass and suspended sediment, thus favouring an ecosystem shift to more turbid conditions. Low and medium crayfish densities reduced macrophyte biomass similarly for both species in monocultures. However, in mixed cultures, low crayfish densities (2 crayfish m−2) reduced the above‐ and belowground biomass of the canopy‐forming H. verticillata more than that of low‐growing V. natans, supporting our hypothesis. This support of low‐growing macrophytes occurred despite a temporal facilitation of shading by increased periphyton biomass. Our results show that the impact of crayfish invasions on aquatic ecosystems is strongly dependent on their density. High densities facilitate the loss of macrophytes and increase the likelihood of ecosystem collapse into a turbid state. However, low densities can provide a competitive advantage to low‐growing macrophytes that would otherwise be outcompeted by canopy‐forming species. Although complete eradication is often impossible, management of invasive crayfish can target densities that have potentially positive effects on invaded ecosystems.

From subsidies to stressors: Positively skewed ecological gradients alter biological responses to nutrients in streams.

Subsidy-stress gradients offer a useful framework for understanding ecological responses to perturbation and may help inform ecological metrics in highly modified systems. Historic, region-wide shifts from bottomland hardwood forest to row crop agriculture can cause positively skewed impact gradients in alluvial plain ecoregions, resulting in tolerant organisms that typically exhibit a subsidy response (increased abundance in response to environmental stressors) shifting to a stress response (declining abundance at higher concentrations). As a result, observed biological tolerance in modified ecosystems may differ from less modified regions, creating significant challenges for detecting biological responses to restoration efforts. Using the agriculturally dominated Mississippi Alluvial Plain (MAP) ecoregion in Mississippi, USA, as a case study, we tested the hypothesis that macroinvertebrate taxa that typically display a subsidy response to nutrient enrichment in less modified ecoregions (i.e., nutrient-tolerance) shift to a stress response to increasing nutrients in highly modified watersheds with elevated baseline nutrient conditions (i.e., nutrient intolerance). The abundance and diversity of MAP-specific intolerant taxa identified with threshold indicator taxa analysis were either unresponsive or exhibited a subsidy response to increasing nutrients in less modified ecoregions in Mississippi with less land alteration and lower nutrient concentrations, but declined at higher concentrations, providing evidence for a stress response to elevated nutrients in the MAP. Additionally, MAP-specific tolerant and intolerant taxa richness responded to increased nutrients predictably and consistently across space and time within the MAP. However, in MAP streams, elevated specific conductance was predicted to dampen the response of tolerant and intolerant taxa richness to increasing nutrient concentrations, highlighting the importance of considering multistressor interactions when interpreting biological data. Lastly, we demonstrate the efficacy of this approach with sediment bacterial communities characterized with amplicon sequencing, which lack sufficient life history characteristics necessary for the development of multimetric indices. Both macroinvertebrate and bacterial communities responded similarly to increasing nutrient concentrations, suggesting DNA-based approaches may provide an efficient biological assessment tool for monitoring water quality improvements in highly modified watersheds.

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.

Performance of co-composting Pholiota nameko spent mushroom substrate and pig manure at different proportions: Chemical properties and humification process

Co-composting is the controlled aerobic degradation of organics, using more than one feedstock. By combining the spent mushroom substrate of Pholiota nameko (SMS) and pig manure (PM), the benefits of each could be used to optimize the composting process and the final product. This study introduced a comprehensive evaluation strategy aimed at identifying the optimal co-composting ratio for these two substrates. A 120-day composting trial was conducted, blending SMS and PM in various ratios to evaluate the benefits of co-composting SMS-PM. The results indicated that dissolved organic matter (DOM) in SMS-derived compost primarily originated from plants, whereas PM-derived compost predominantly consisted of microbial metabolic products, and co-composting combined both sources. An increase in aromaticity and humification degree of DOM occurred during the composting process itself rather than being derived from autochthonous origin. Carbohydrates like phenols and alcohols broke down during composting, and microbes utilized polysaccharides as an energy source for humus formation. As co-composting progressed, the treatments with varying mass ratios of SMS to PM, including 8:2, 7:3, 6:4, 5:5, 4:6, and 3:7 were observed to result in a decline in aliphatic hydroxylated chains alongside an enhancement in aromaticity within the compost. Additionally, there was a conversion from organic carbon (C) to carboxyl C within humic acid (HA) due to oxidation and dehydrogenation processes that facilitated the formation of stable nitrogen-containing compounds characterized by condensed aromatic structures. Following thorough evaluation, it was determined that optimal composting efficacy occurred at a mass ratio of SMS to PM equal to 6:4. Post-compost analysis revealed increases in nutrient content; specifically, germination index (GI) value reached 132.7%, while organic matter content attained 45.3%. Conversely, electrical conductivity (EC), C contents of water-soluble substances and humin (Cwss and CHu) decreased by approximately 11.8%, 73.4%, and 29.8% respectively; meanwhile, C contents of humic-extracted acid and HA (CHE and CHA), along with degree of polymerization (DP), increased by 17.3%, 20.3% and 9.9% respectively. The proposed co-compost formula not only facilitated simultaneous recycling of both SMS and PM waste but also transformed them into high-quality organic fertilizers suitable for soil enrichment—effectively addressing challenges faced by both edible fungi cultivation and livestock industries while augmenting organic fertilizer sources for Black land protection.

Large igneous provinces played a major role in oceanic oxygenation events during the mid-Proterozoic

AbstractLow atmospheric oxygen levels during the mid-Proterozoic were occasionally interrupted by transient high oxygen levels. The cause of mid-Proterozoic ocean redox variability remains unclear. Here we investigate mercury chemostratigraphy across the Jixian section of North China Craton through two oxygenation intervals. Abnormal spikes in mercury concentration and excursions of mercury isotopes are observed in the Dahongyu and Hongshuizhuang formations, which occur just below the two oxygenation intervals, respectively. These mercury anomalies suggest that the two oxygenation events were preceded by subaerial volcanism. Furthermore, the two oxygenation intervals show increased nutrient concentrations and negative shifts in mercury isotopes, indicating that enhanced weathering and terrestrial nutrient influx occurred during oxygenation intervals. We infer that in the breakup setting of the Columbia supercontinent, large igneous province volcanism and its efficient low-latitude weathering could rapidly increase terrestrial nutrient influx into the ocean, promoting oceanic productivity and a pulsed rise in oxygen levels.

Hydromorphological pressure explains the status of macrophytes and phytoplankton less effectively than eutrophication but contributes to water quality deterioration

Hydromorphological alterations are among the human-induced pressures that must be considered when assessing the ecological status of aquatic ecosystems. We investigated the effects of hydromorphological pressures on the ecological status of lowland lakes in Poland, focusing particularly on macrophyte and phytoplankton conditions. The analysis was based on biological, hydromorphological, and physicochemical data collected from 30 lowland lakes. Almost all biological and physicochemical indices correlated significantly (Spearman's |R|>0.5) with the hydromorphological index LHMS_PL. Using the variation partitioning method, we found that hydromorphological pressures explained only a small proportion (5.5 %) of the variability in ecological status assessed using macrophytes. These pressures had no direct effects on the ecological status assessed using phytoplankton. The shared effects of physicochemistry and hydromorphology explained a large proportion of the variability in ecological status indices based on both phytoplankton and macrophytes. The results demonstrated that in the analysed lakes, hydromorphological alterations were usually accompanied by increased nutrient concentrations. This finding indicates that physical alterations may affect lake biological assemblages not only directly but also indirectly by reducing the ecosystem's natural buffering capacity, thereby promoting the eutrophication process.

Mangrove afforestation as an ecological control of invasive Spartina alterniflora affects rhizosphere soil physicochemical properties and bacterial community in a subtropical tidal estuarine wetland

Background The planting of mangroves is extensively used to control the invasive plant Spartina alterniflora in coastal wetlands. Different plant species release diverse sets of small organic compounds that affect rhizosphere conditions and support high levels of microbial activity. The root-associated microbial community is crucial for plant health and soil nutrient cycling, and for maintaining the stability of the wetland ecosystem. Methods High-throughput sequencing was used to assess the structure and function of the soil bacterial communities in mudflat soil and in the rhizosphere soils of S. alterniflora, mangroves, and native plants in the Oujiang estuarine wetland, China. A distance-based redundancy analysis (based on Bray–Curtis metrics) was used to identify key soil factors driving bacterial community structure. Results S. alterniflora invasion and subsequent mangrove afforestation led to the formation of distinct bacterial communities. The main soil factors driving the structure of bacterial communities were electrical conductivity (EC), available potassium (AK), available phosphorus (AP), and organic matter (OM). S. alterniflora obviously increased EC, OM, available nitrogen (AN), and NO3−-N contents, and consequently attracted copiotrophic Bacteroidates to conduct invasion in the coastal areas. Mangroves, especially Kandelia obovata, were suitable pioneer species for restoration and recruited beneficial Desulfobacterota and Bacilli to the rhizosphere. These conditions ultimately increased the contents of AP, available sulfur (AS), and AN in soil. The native plant species Carex scabrifolia and Suaeda glauca affected coastal saline soil primarily by decreasing the EC, rather than by increasing nutrient contents. The predicted functions of bacterial communities in rhizosphere soils were related to active catabolism, whereas those of the bacterial community in mudflat soil were related to synthesis and resistance to environmental factors. Conclusions Ecological restoration using K. obovata has effectively improved a degraded coastal wetland mainly through increasing phosphorus availability and promoting the succession of the microbial community.

Phosphogypsum with Rice Cultivation Driven Saline-Alkali Soil Remediation Alters the Microbial Community Structure.

The improvement of saline-alkali land plays a key role in ensuring food security and promoting agricultural development. Saline soils modifies the response of the soil microbial community, but research is still limited. The effects of applying phosphogypsum with rice cultivation (PRC) on soil physicochemical properties and bacterial community in soda saline-alkali paddy fields in Songnen Plain, China were studied. The results showed that the PRC significantly improved the physicochemical properties of soil, significantly reduced the salinity, increased the utilization efficiency of carbon, nitrogen, and phosphorus, and significantly increased the activities of urease and phosphatase. The activities of urease and phosphatase were significantly correlated with the contents of total organic carbon and total carbon. A redundancy analysis showed that pH, AP, ESP, HCO3-, and Na+ were dominant factors in determining the bacterial community structure. The results showed that PRC could improve soil quality and enhance the ecosystem functionality of soda saline-alkali paddy fields by increasing nutrient content, stimulating soil enzyme activity, and regulating bacterial community improvement. After many years of PRC, the soda-alkali soil paddy field still develops continuously and healthily, which will provide a new idea for sustainable land use management and agricultural development.

Sedimentary record of primary productivity changes in a crater lake in Northeast China since the Last Glacial Maximum

High-resolution primary productivity records are valuable for identifying lacustrine ecosystem degradation in the context of long-term climatic variability. In this paper, we analyse primary productivity changes in a seasonally ice-covered crater lake (Lake Tuofengling) in northeast China since the Last Glacial Maximum using biogenic silica content and the carbon preference index of short-chain n-alkanes as proxies. Results show that primary productivity was lower during the cold and dry glacial period, whereas it was higher during the warm and humid Holocene. During the last deglaciation, primary productivity experienced a ∼ 1.5-kyr lagged response to Bølling-Allerød warming, and multiple oscillations during the Younger Dryas. Additionally, the peak productivity of the entire profile also occurred during this period. These fluctuations and the highest primary productivity are suggested to be the result of the combined influences of increased summer temperatures and regional permafrost melting. The current state of primary productivity in Lake Tuofengling is moderate but has been increasing since the abrupt increase in diatom productivity after ∼3 ka B.P. This stage is associated with increased dust deposition and longer ice-free periods under winter-warming conditions. We suggest that longer seasonal stratification under the current warmer winters and increased nutrient concentrations caused by decreased lake level will increase the risk of lake ecosystem degradation in the future.

Response to Addition of Lighting Duration and Electrical Induction in Lettuce (Lactuca sativa L.) Plant on the Uptake of Nitrogen, Phosphors, Potassium and Yield

Background: The impact of excessive use of chemical fertilizers and pesticides causes problems of land degradation, low fertility levels and reduced cation exchange capacity. To increase nutrient uptake and yield of lettuce plants, cultivation techniques using induction and additional lighting are needed. The aim is to increase nutrient absorption and plant yields. Methods: The research design used a split plot with Factorial Randomized Groups. Factor 1 Lighting duration (P) for 4 and 8 hours per day and Factor 2, induction with DC (Direct Current) current (S). Induction 1 time per day (S1); The treatment in this study was repeated 4 times. Induction 2 times per day (S2) and Induction 3 times per day (S3). Result: The combination P2S2 showed good results regarding the uptake of Nitrogen (20.1 Kg.Ha-1), Phosphorus (2.71 Kg.Ha-1) and Potassium (67.23 Kg.Ha-1) in plant leaves. The P1S2 treatment showed a leaf area of (1652.19 cm2). The adding 4 hours of light and an induction interval of 2 times per day gave good results on the uptake of Nitrogen, Phosphorus and Potassium in the leaf of lettuce plants.

Impact of Long-term Application of Fertilizers and FYM on Nutrient Uptake by Soybean Crop and Properties of Black Soil

Long Term Fertilizer Experiment (LTFE) play an important role in understanding the complex interactions involving plant, soil, climate, management practices and their effect on soil productivity over a long period of time. The present investigation is a part of ongoing All India Coordinated Research Project on Long Term Fertilizer Experiment with Soybean-Wheat Cropping Sequence, which was initiated since 1972. The experiment was carried out in a randomized block design consisting of eight treatments, viz. 50% NPK, 100% NPK, 150% NPK, 100% NP, 100% N, FYM (100% NPK+FYM), 100% NPK (-S) and Control. The significant nutrient content with nutrient uptake by soybean was noted in 100% NPK+FYM treatment over the control plot. It was also observed that nutrient content with nutrient uptake increased significantly with consecutive doses of fertilizers. On the other hand, 100% N and in the control group had the lowest value. However, adding fertilizer P in addition to N (100% NP) increased nutrient content and nutrient uptake by soybean crop. The highest. Soil organic carbon content was recorded with 100% NPK dose+FYM followed by 150% NPK treatment combination which could apparently due to the synergistic contribution of integration of fertilizer and FYM application. Similarly, the available N,P, K and S content in soil were found highest with 100% NPK + FYM followed by 150% NPK fertilizer dose. However, the lowest content was noted in control where crop was grown without fertilizers. Available sulphur was significantly higher over control in all the treatments receiving single super phosphate.

Eutrophication of Lakes: From Global Process to Regional Implication in the Kola Arctic Region

ABSTRACTEutrophication of water bodies is analysed as a global process. The volumes of globally increasing use of nitrogen and phosphorus are demonstrated, with the dispersion of these elements leading to increased nutrient contents in lakes and rivers. Results of original studies on remote lakes in the Arctic zone indicate that the content of nutrients in these lakes has increased over the past decades. Concentrations of nitrogen, phosphorus and organic matter in lake waters tend to increase in the absence of anthropogenic effects. Simultaneously, the silicon concentrations were found to decrease because of the consumption by diatoms. Low concentrations of bioavailable nutrients confirm that these nutrients are rapidly spent in the production processes of ecosystems. The calculated trophic state index (according to R. Carlson) indicates that the number of oligotrophic lakes in the forest tundra zone decreased by 50% by 2010–2018, and these lakes are absent from the northern taiga zone. Temperature increase and climate warming in the Arctic zone first caused the increase in the contents of nutrients in the lakes and their trophic states.

Enhancing the Nutritional Quality of Defatted Cottonseed Meal by Solid-State Fermentation with Probiotic Microbes

Defatted cottonseed meal (DCSM), a byproduct of the cotton industry, is highly regarded for its high protein content, making it a source of nutrients in animal feed. Traditional physical and chemical treatments of DCSM can lead to a reduction in nutrient content and the presence of residual organic solvents. Probiotic fermentation of DCSM offers several advantages, including degradation of anti-nutritional factors, an increase in nutrient content, and production of beneficial metabolites. This study employed probiotic fermentation of DCSM using a probiotic microbe collection composed of Saccharomyces cerevisiae, Enterococcus faecium, and Lactiplantibacillus plantarum. This fermentation process significantly enhanced the nutritional quality of DCSM. Specifically, the contents of crude protein, free amino acid, total phosphorus, and moisture increased by 1.14-fold, 1.14-fold, 1.24-fold, and 3-fold, respectively. In the meanwhile, there was a substantial reduction in the content of dry matter, crude ash, and crude fat, with decreases of 27.83%, 25.74%, and 88.23%, respectively. Probiotic fermentation of DCSM resulted in an overall enhancement of the palatability of DCSM. This study provides valuable insights into the potential of mixed probiotic fermentation as a promising approach for improving the nutritional quality of DCSM.

Analysis of the relationship between primary productivity, phytoplankton abundance and nutrients in Cengklik Reservoir, Boyolali

Cengklik Reservoir is a reservoir that has many benefits for the surrounding community such as irrigation and aquaculture, namely Floating Net Cages. FNC in these waters can have an impact on the remaining feed produced in cultivation. The rest of the feed can cause increased nutrient concentrations and eutrophication in the waters. These impacts can affect water quality conditions, phytoplankton abundance and primary productivity. The purpose of this study was to determine the primary productivity, abundance of phytoplankton, nitrate (NO3) and orthophosphate (PO4) in Cengklik Reservoir, Boyolali. The study was conducted in March 2023. The sampling point determination method uses Stratified Random Sampling with four stations in two repeats. Data processing using simple and multiple linear regression analysis with Jamovi application. The results obtained gross primary productivity value is 62.50 – 156.25 mgC/m3/hour while net primary productivity is 31.25 – 93.75 mgC/m3/hour. The abundance of phytoplankton results the most in the Cyanophyceae class with a percentage of 50.72% - 65.06%. The relationship between phytoplankton abundance and gross primary productivity is obtained R2 = 0.142 while net primary productivity R2 = 0.608 which means that the relationship of phytoplankton abundance affects the production of net primary productivity in waters. The relationship between nitrate and phosphate analysis with phytoplankton abundance in waters R2 = 0.311 which means that nitrate and orthophosphate have a low influence on phytoplankton abundance. The abundance of phytoplankton in waters can be influenced by other factors.Keywords: Cyanophyceae; Nitrate; Orthofosfat; Phytoplankton

Assessing and Quantifying the Carbon, Nitrogen, and Enzyme Dynamics Effects of Inter-row Cover Cropping on Soils and Apple Tree Development in Orchards

Cover crops between rows in orchards can improve the development of soil resources and increase agricultural productivity. However, there have been few reports of cover crops that can act as a “green manure” in apple orchards across arid and semiarid zones. This study investigated the effects of planting interrow vegetation on soil properties and apple tree performance during a 32-month experiment. There were six treatments: clean cultivation as a control; natural grass planting; planting with ryegrass; planting with alfalfa; planting with tall fescue; and planting with villous wild pea cover crops. The treatments primarily affected the 0- to 20-cm surface soil layer. Soil carbon, nitrogen, and enzyme levels initially decreased (during the first 12–24 months); then, they increased (24–32 months). The cover crops significantly increased nutrient contents (soluble organic carbon, microbial carbon and nitrogen, alkaline dissolved nitrogen, nitrate nitrogen, and ammonium nitrogen) in the 0- to 20-cm soil layer by more than 19.6% and increased the related enzyme activities by more than 25.2%. The alfalfa and wild pea alleys had a stronger effect on the soil environment than the control, natural grass, ryegrass, and tall fescue alley treatments; however, after 32 months, the alfalfa treatment inhibited fruit tree growth and development. This was unexpected because alfalfa seemed to have a positive effect on soil fertility characteristics. Under local ecological conditions, villous wild pea had the greatest effect on apple orchard productivity and significantly increased short branching by 15.9%, fruit weight per fruit by 12.6%, yield per plant by 8.6%, and soluble sugar content by 10.5% compared with clean cultivation. The correlation analysis showed that there were significant or highly significant positive correlations between fruit tree performance and soil carbon, nitrogen, and enzyme activity levels as the soil layer depth increased. Therefore, under local ecological conditions, cover crops have a greater effect on orchard surface soil fertility than on deeper soils, and intercropping with villous wild pea potentially produces the greatest improvement in apple orchard productivity.

Isolation and assessment of the beneficial effect of exopolysaccharide-producing PGPR in Triticum aestivum (L.) plants grown under NaCl and Cd -stressed conditions

Exopolysaccharide (EPS)-producing beneficial bacteria play a multifaceted role in improving plant growth and adaptive responses against different stressors. In this study, we isolated 25 bacterial strains from pea nodules and were further studied for their sodium chloride (NaCl) and cadmium (Cd) stress tolerance. Based on our results, Rhizobium fabae SR-22 (NCBI Accession number: MG063739.1) showed better tolerance toward salinity and Cd stress and produced a wide range of plant growth-promoting compounds. However, the amount of EPS varies during NaCl and Cd stress. It was important to note that NaCl and Cd beyond the tolerant level, affected the morphology and cellular viability of R. fabae. Interestingly, plant growth-promoting (PGP) substances (indole-3-acetic acid, ammonia, siderophore, and ACC deaminase) released by R. fabae were increased with increasing NaCl concentrations. In contrast, PGP substances were greatly decreased by increasing Cd dosages. Further, the beneficial effect of EPS-producing R. fabae in Triticum aestivum grown in soil treated with different levels of NaCl and Cd was assessed. Inoculation of R. fabae in wheat seedlings grown under higher NaCl and Cd concentrations showed improved growth compared to non-inoculated plants. R. fabae exhibited maximum effect in wheat plants grown under 2% NaCl and increased seed germination (8%), root length (13%), vigor indices (19%), root biomass (20%), chlorophyll-a (31%), total chlorophyll (27%) and carotenoid content. Additionally, R. fabae increased Cd and NaCl tolerance in wheat seedlings and improved their antioxidative responses. Conclusively, this work demonstrated that EPS-producing R. fabae showed a promising role in mitigating salinity and Cd-stress in wheat possibly by reducing salt and HM stress-induced abrasions and growth promotion via inorganic phosphate solubilization, and increased nutrient absorption. In the future, R. fabae equipped with these distinguishing characteristics may be used as effective bio-inoculants/bio-formulations in agriculture to address salinity and HM stress issues.

Recycling Agricultural Waste to Enhance Sustainable Greenhouse Agriculture: Analyzing the Cost-Effectiveness and Agronomic Benefits of Bokashi and Biochar Byproducts as Soil Amendments in Citrus Nursery Production

Applying bokashi (Bok) at 10% volume/volume (v/v), biochar (BC) at 10% v/v, and their combination (Bok_BC) as soil amendments significantly enhances citrus nursery production, improving plant growth and soil health, alongside offering notable economic benefits. Our greenhouse experiment evaluated these treatments across two fertilizer doses, at half (700 μS/cm) and full (1400 μS/cm) electrical conductivity (EC) levels, compared to a control mix, demonstrating improved nutrient availability, water retention, growth rates, and potential for carbon sequestration. Based on the results of this experiment, a cost–benefit analysis was performed; the BC treatment yielded substantial savings, particularly in large nurseries where BC at 700 μS/cm electrical conductivity (EC) saved USD 1356.38 per day and the same treatment at 1400 μS/cm EC saved USD 1857.53. These savings stem from increased nutrient contents (N, P, and K) and improved water retention, reducing irrigation; shortened growth cycles due to enhanced growth rates were observed, indirectly suggesting reduced electricity costs for greenhouse operations. Additionally, the increased carbon content within the soil points toward long-term benefits from carbon sequestration, further contributing to the sustainability and economic viability of these practices. These findings highlight the economic advantage of incorporating Bok and BC into soil mixes, providing a cost-effective strategy for enhancing greenhouse agriculture sustainability.

Utilization of Tofu Liquid Waste as Liquid Organic Fertilizer Using the Fermentation Method with Activator Effective Microorganisms 4 (EM-4): A Review

<p><span><strong>ABSTRACT.</strong> Liquid organic fertilizer is organic fertilizer in liquid form which is partly or wholly derived from organic compounds such as plant, animal and industrial residues, in solid or liquid form. The nutrients contained in it are in the form of a very fine solution so that it is easily absorbed by plants, even the leaves or stems. Organic fertilizer is one solution to restore soil minerals physically, chemically and biologically from the bad effects of synthetic fertilizers. Liquid fertilizer is obtained from a solid fermentation process first, then followed by a liquid anaerobic fermentation and extraction process. In the fermentation process, the role of microbes greatly determines the product produced. Tofu liquid waste is made from cooking residue from cooked soybeans boiled and the water from the remaining tofu tends to be thrown into the surrounding environment. Waste Liquid tofu contains organic ingredients, namely carbohydrates reaching 20-50%, protein 40-60%, and 10% fat. It is known that this tofu waste can be used as liquid organic fertilizer by fermentation. Tofu liquid waste contains organic substances, namely carbohydrates, proteins and fats, which can be used as liquid organic fertilizer. These substances must first be broken down into simpler elements by a fermentation process so that they can be absorbed by plants. Effective Microorganisms-4 as inoculants to increase microbial diversity in soil and can control unpleasant odors, accelerate the decomposition process, maximize the decomposition process, increase nutrient content, reduce the growth of pathogenic microorganisms, improve the physical, chemical and biological structure of the soil and bioremediation.</span></p><p><strong>Keywords: </strong></p><p align="left">Liquid Organic Fertilizer, Liquid Waste, Fermentation, Effective Microorganisms-4, Nutrient</p><p><strong><br /></strong></p><p><span><br /></span></p>