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Understanding the distribution and dynamics of particulate organic carbon (POC) is essential for assessing marine ecosystem health and carbon cycling. This study analyzed the spatial and temporal variability of POC in the northeastern coastal waters to the continental shelf of the Gulf of Mexico using satellite remote sensing data within the United States. Over 19 years, surface water POC averaged 155.57 ± 13.56 mg/m3, with values ranging from 127.17 to 188.81 mg/m3, and an insignificant annual increase of 0.78 mg/m3. Spatial analysis across five transects (T1–T5) revealed significant variability, with mean POC values ranging from 125.19 mg/m3 (T5) to 169.23 mg/m3 (T1) and standard deviations from 136.76 mg/m3 (T5) to 193.64 mg/m3 (T3). Transects near the estuaries of the Mississippi and Atchafalaya Rivers (T1–T4) exhibited elevated POC due to terrestrial organic matter and nutrient inputs, while the west Florida shelf (T5) had lower concentrations. Seasonal variations were influenced by wind-driven currents, sea surface temperature (SST), and mesoscale eddies. Analysis of Variance showed a significant seasonal effect on POC concentrations (F-value: 96.51, p < 0.001). A strong negative correlation between SST and POC during winter and fall suggests cooler temperatures enhance vertical mixing and nutrient upwelling, increasing POC. In contrast, warmer SSTs in summer were positively correlated with POC due to stratification and increased biological activity. Chlorophyll-a showed a strong positive correlation with POC, highlighting the role of primary productivity. These results emphasize the importance of satellite-based POC monitoring for a comprehensive understanding of carbon cycling and its biological impacts on marine ecosystems. [ABSTRACT FROM AUTHOR]

The Asan Wetland is an important freshwater wetland in Uttarakhand's Dehradun district. It is known for its diverse flora and fauna and as a stopover for migratory birds. Periphyton, an essential biological component of aquatic ecosystems, serves as a bioindicator of water quality and ecosystem integrity. This study fills a gap in our knowledge of the Asan Wetland's ecological health by analyzing periphyton populations and a number of physicochemical characteristics across three selected sites from November 2021 to October 2023. Selected sites named as Site 1(S1), Site 2(S2), Site 3 (S3). Monthly variations in parameters such as water temperature, pH, turbidity, transparency, total dissolved solids (TDS), electrical conductivity, dissolved oxygen (DO), total hardness, alkalinity, biological oxygen demand (BOD), chemical oxygen demand (COD), and nutrients were collected, identified and assessed using Ms-excel and Past software. Phosphorus levels in the Asan Wetland indicated a moderate to high nutrient load , peaking in August (1.20–1.25 mg/L) across all three sites and dropping to their lowest in January (0.35–0.65 mg/L). Nitrate levels were moderate, with the highest concentrations in December (1.40–1.55 mg/L) and the lowest in July (0.25–0.35 mg/L), showing similar seasonal patterns across sites. The periphyton was represented in this study by 18 different periphytic taxa that belong to three different classes. These classes include Bacillariophyceae (Cymbella, Navicula, Nitzschia, Fragilaria Meridion, Synedra, Gomphonema, Tabellaria, and Diatoma), members of the Chlorophyceae Ulothrix, Spirogyra, Cosmarium, Microspora, Chlorella, Oedogomium, Zygnema, and Cladophora are, while Phormidium is a member of the Cyanophyceae. The peak periphytic density (individuals/cm2) recorded was 322.67 ± 89.08 × 103 in January, with all three classes exhibiting maximum values at S3, the minimum periphytic density (individuals/cm2) recorded was 18 ± 5.57 × 10³ in August. The annual percentage composition of periphytic flora in the Asan wetland over 2 years indicates that Bacillariophyceae constituted the predominant group (89%–90%), succeeded by Chlorophyceae (7%–9%) and Cyanophyceae or Myxophyceae (1%–4%) across three sites. The canonical correspondence analysis (CCA) of periphyton among different sites during both years of the study suggested that S3 was more diverse, followed by S1 and S2, represented 64.93%, 35.07% of the variance with eigenvalues of 0.01794, 0.00968 respectively. PCA suggested that PC1 and PC2 were represented by 93.98% and 6.015% of the variance with eigenvalues 279.149 and 17.8675, respectively The multivariate cluster analysis showed the similarity of periphyton at three different sites during the 2-year study. The findings of this study emphasize the need for targeted management strategies to maintain the ecological health of the Asan Wetland. [ABSTRACT FROM AUTHOR]

Freshwater ecosystems face increasing pressures from human activities, leading to degraded water quality and altered habitats for aquatic species. This study investigates the relationship between water quality and waterbird distribution along the Lieve River, Belgium, based on manually conducted waterbird counts and water quality data collected from 48 transects in March 2024. Localized eutrophication was evident, with TN (2.7–5.6 mg L−1), TP (up to 0.46 mg L−1), and chlorophyll-a (median 70 ppb) exceeding environmental thresholds. Prati index analysis revealed that 58.3% of the sampling points along the Lieve River were categorized as "polluted", reflecting extensive water quality degradation. Eurasian coots (71.4%) and wild ducks (72.4%) were predominantly found in polluted areas, thriving in nutrient-enriched habitats linked to high TP levels. In contrast, common moorhens (80.3%) preferred acceptable quality areas, indicating higher water quality requirements. These findings indicate that phosphate is a key driver of waterbody eutrophication, as evidenced by the TP concentrations measured on-site, which far exceed the thresholds set by environmental standards. Future research should explore advanced monitoring approaches to improve waterbird and water quality assessments, ensuring the conservation of the Lieve River as one of Europe's oldest artificial canals, and the protection of its waterbird habitats. [ABSTRACT FROM AUTHOR]

Applying fertilizers correctly is crucial for enhancing soil fertility and crop productivity. Nonetheless, the long-term effects of slag-based gypsum (SBG) and commercial gypsum (CG) on soil fertility and crop yield remain poorly understood. Field experiments were conducted over six seasons with rice crops to investigate the impact of long-term application of four levels (300, 450, 600, and 750 kg ha−1) of SBG and CG, in conjunction with the recommended dose of fertilizer (RDF), on soil fertility, nutrient uptake, and rice yield. Long-term fertilization with varying levels of SBG and CG significantly influenced the overall rice yield, with the highest grain and straw yields recorded at 750 kg SBG ha−1 (6.90 ± 0.14 and 9.59 ± 0.33 t ha−1, respectively). The application of SBG and CG over the long term had minimal impact on soil pH while notably increasing nutrient uptake and soil fertility. There was a significant correlation between SBG, CG, and soil nutrients, except for soil pH and potassium (K). Principal component analysis (PCA) highlighted that the application of 450, 600, and 750 kg SBG ha−1, as well as 600 and 750 kg CG ha−1, exhibited distinct behavior and outperformed other doses concerning soil nutrients and their uptake. The long-term application of SBG and CG, in combination with RDF, led to an increase in soil fertility and rice yield. However, the long-term application of 450 kg SBG ha−1 yielded comparable results to 600 and 750 kg ha−1 of both SBG and CG, suggesting its efficacy over time. [ABSTRACT FROM AUTHOR]

Approximately 7% of the Earth's land surface is affected by salinity, resulting in significant agricultural losses. Salt stress is characterized by the presence of an elevated concentration of soluble salts within the root zone, leading to the development of osmotic stress and ion toxicity in the plant throughout its growth. The presence of elevated levels of salt in soil is a significant abiotic stress factor that has a detrimental impact on the growth, development, and production of agricultural crops. The issue of salt stress arises as a significant matter when agricultural fields, which were once fertile and productive, experience a more pronounced salinization due to both human activity and natural factors. Sodic soils have a detrimental impact on plant growth due to elevated soil pH levels and unfavorable physical properties caused by an excessive accumulation of exchangeable sodium ions. Sodium ions (Na+) have been found to exert significant deleterious effects on plant growth due to their harmful impact on plant metabolism via suppressing enzyme activities. The maintenance of plant growth and yield development relies on the activation of enzymatic processes in the cytoplasm, which requires an appropriate ratio of potassium (K+) to sodium (Na+). The reclamation of salt-affected soils is necessary in order to restore their productivity and hence enhance food production. Various strategies have been employed for the effective management of saline-alkali soils. These approaches encompass leaching, incorporation of diverse organic and inorganic amendments, mulching, and the cultivation of salt-tolerant crops. Hence, the current study is centered on multiple facets of salt-affected soils, their impact on plant life, and diverse strategies for rehabilitating salt affected soils in order to improve the capacity for agricultural yield. [ABSTRACT FROM AUTHOR]

Rivers play a crucial role in nutrient cycling, yet are increasingly affected by eutrophication due to anthropogenic activities. This study focuses on the Barato River in Hokkaido, Japan, employing an integrated approach of field measurements and Sentinel-2 satellite remote sensing to monitor eutrophication as the river experiencing huge sewage effluents. Key parameters such as chlorophyll-a (Chla), dissolved inorganic nitrogen (DIN), dissolved inorganic phosphorus (DIP), and Secchi Disk Depth (SDD) were analyzed. The developed empirical models showed a strong predictive capability for water quality, particularly for Chla (R2 = 0.87), DIP (R2 = 0.61), and SDD (R2 = 0.82). Seasonal analysis indicated peak Chla concentrations in October, reaching up to 92.4 μg/L, alongside significant decreases in DIN and DIP, suggesting high phytoplankton activity. Advanced machine learning models, specifically back propagation neural networks, improved the prediction accuracy with R2 values up to 0.90 for Chla and 0.83 for DIN. Temporal analyses from 2018 to 2022 consistently revealed the Barato River's eutrophic state, with severe eutrophication occurring for 33% of the year and moderate for over 50%, emphasizing the ongoing nutrient imbalance. The strong correlation between DIP and Chla highlights phosphorus as the main driver of eutrophication. These findings demonstrate the efficacy of integrating remote sensing and machine learning for dynamic monitoring of river eutrophication, providing critical insights for nutrient management and water quality improvement. [ABSTRACT FROM AUTHOR]

Optimizing forest management requires a comprehensive understanding of how soil properties and microbial communities evolve across different plantation ages. This study examines variations in soil nutrient dynamics, enzyme activities, and bacterial communities in Schima superba Gardn. & Champ plantations of 10, 15, 27, 55, and 64 years. By analyzing soil from depths of 0–20 cm, 20–40 cm, and 40–60 cm, we identified significant age-related trends in soil characteristics. Notably, nutrient contents, including total organic carbon (TOC), total phosphorus (TP), total carbon (TC), total nitrogen (TN), and nitrate nitrogen ( NO 3 − -N), as well as soil water content (SWC), peaked in 55-year-old mature plantations and decreased in 64-year-old over-mature plantations. Enzyme activities, such as urease, sucrase, and acid phosphatase, decreased with soil depth and exhibited notable differences across stand ages. Microbial community analysis indicated the predominance of Acidobacteria, Chloroflexi, Proteobacteria, Actinobacteria, and Verrucomicrobiota in nutrient cycling, with their relative abundances varying significantly with age and depth. Mature and over-mature plantations exhibited higher absolute abundances of functional genes related to methane metabolism, nitrogen, phosphorus, and sulfur cycling. Reduced calcium ion levels were also linked to lower gene abundance in carbon degradation, carbon fixation, nitrogen, and phosphorus cycling, while increased TOC, NH 4 + -N, NO 3 − -N, and AP correlated with higher gene abundance in methane metabolism and phosphorus cycling. Our findings suggest that long-term cultivation of Schima superba enhances soil nutrient cycling. Calcium ion was identified as a significant factor in assessing soil properties and microbial dynamics across different stand ages, suggesting that extended plantation rotations can improve soil health and nutrient cycling. [ABSTRACT FROM AUTHOR]

Abstract This study investigates the intricate dynamics of nutrient transport and stratification in Lake Biwa, highlighting the significant impact of river inflows on water quality. Utilizing a validated three-dimensional flow field model and ecosystem model including a bottom sediment model, the analysis revealed that nutrient concentrations, specifically NH₄⁺, NO₂⁻, NO₃⁻, and PO₄3⁻, exhibited pronounced seasonal variations. In the RN_double scenario, NH₄⁺ and NO₂⁻ concentrations demonstrated a slight increase of 0.1 µg/L, respectively, while NO₃⁻ concentrations rose by 0.05–0.10 µg/L in response to precipitation changes. Conversely, in the RN_half scenario, NH₄⁺ and NO₂⁻ concentrations decreased, with NO₃⁻ seeing a more substantial decline of approximately 0.1 µg/L, attributed to reduced precipitation. PO₄3⁻ levels exhibited a maximum decrease of 0.03 µg/L from summer to autumn. Furthermore, simulations limiting nutrient inflows indicated a modest reduction in concentrations: NH₄⁺ decreased by approximately 0.03 µg/L during summer, and NO₂⁻ decreased by around 0.05 µg/L from spring to summer. The results suggest that while immediate improvements in dissolved oxygen levels are limited, effective long-term nutrient management could stabilize oxygen concentrations and improve overall water quality. These findings underscore the necessity for comprehensive water management strategies to mitigate eutrophication effects and support the ecological health of Lake Biwa.

Irrigation remains important to meet the needs of the people by increasing agricultural productivity. However, its water productivity in developing countries is low due to inefficient irrigation water management. The main objective of this study was to evaluate soil water, crop growth and nutrient dynamics under different irrigation techniques. Hydrus-1D model was used to simulate soil water content (SWC), actual evapotranspiration (ETa) and soil leachates. The model performance was evaluated by comparing the measured and simulated treatment variables. The Hydrus-1D performance showed good agreement between the observed and simulated SWC (R2 = 0.55–0.81; NRMSE = 0.01-0.09; d-index = 0.95-0.99) and with a very good agreement for nitrate-nitrogen (NO3–N) leaching (R2 = 0.97, d index = 0.99 and NRMSE = 0.02). Similarly, performance in simulating PO4-P were acceptable (R2 = 0.88; d index = 0.99; NRMSE = 0.04). The value of SWC (cm3 cm−3) ranged from 0.30 to 0.38 at 10 cm and from 0.27 to 0.37 at 20 cm soil depths. The seasonal drainage water was reduced to 86%, 87%, and 54 %, respectively for AFI, FFI, and OHI treatments compared with CFI treatment. The NO3–N leaching was reduced by 41%, 71%, and 83% under AFI, FFI, and OHI compared with CFI while phosphate – P (PO4-P) leaching was 60%, 66%, and 79.6%, respectively, lower in AFI, FFI, and OHI than CFI. The highest seasonal ETa (421.95 mm) was found in CFI while the lowest (335.22 mm) was found in AFI treatment. Besides, the highest IWP (9.11 kg/m3) was obtained from AFI technique indicating that that AFI was the most efficient irrigation technique in saving both nutrient and water under onion production. Hydrus-1D could be a successful tool for predicting water and nutrient transport management decisions to improve water and nutrient management.

Soybean production faces many constraints with several factors, such as biotic and abiotic factors, and the crop management practices where inadequate nutrient management leads to a decline in production potential of the crop. Among the biotic factors, exploitation of resources by weeds not only causes a decline in production but also decreases the crop quality. Managing the weeds during the critical period of crop weed competition plays outstanding role in maximizing soybean production. In order to study the influence of integrated nutrient and weed management on nutrient dynamics and yield optimization of soybean an experiment was conducted in Split Plot Design with three nutrient management treatments in main plot {100% recommended dose of fertilizer (RDF), 75% RDF + 25% N through farmyard manure (FYM) + Phosphate solubilizing bacteria (PSB) and 50% RDF + Rhizobium + PSB} and five weed management treatments in the sub-plot (Hand weeding at 15, 30 and 45 DAS, Mechanical weeding at 20 and 40 DAS, Pendimethalin @ 1 kg a.i. ha−1 PE fb Hand weeding at 30 DAS, Propaquizafop @ 0.075 kg a.i. ha−1 PoE fb Hand weeding at 45 DAS, and Weedy check as control). The results indicated that application of 75% RDF + 25% N through FYM + PSB recorded the highest seed yield, nutrient content in seed and uptake of N, P, K, and S in the seed and stover, microbial population, and soil nutrient status. Highest partial factor productivity was recorded under 50% RDF + Rhizobium + PSB. Under weed management, hand weeding recorded the highest growth, yield attributes and nutrient content, but was found to be at par with Pendimethalin @ 1 kg a.i. ha−1 PE fb Hand weeding at 30 DAS and Propaquizafop @ 0.075 kg a.i. ha−1 PoE fb Hand weeding at 45 DAS. Application of 75% RDF + 25% N through FYM + PSB and pendimethalin @ 1 kg a.i. ha−1fb hand weeding at 30 DAS proves to be an effective strategy for soybean cultivation. The experiment was conducted at the experimental farm of School of Agricultural Sciences, Nagaland University, Medziphema, India. [ABSTRACT FROM AUTHOR]

Introduction: The dynamic changes of mineral nutrients in the leaf and branch of Zanthoxylum bungeanum 'Hanyuan' during fruit development can serve as a basis for nutrient diagnosis and scientific fertilization. Methods: The content of Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in the branch and leaf were measured using current-year shoots of 10-year-old Z. bungeanum 'Hanyuan' during the fruit development period, and the corresponding nutrient content in soil of the orchard were also determined to explore the nutrient demand patterns of Z. bungeanum 'Hanyuan' trees. Results: Both branch and leaf exhibited relatively high levels of various nutrients during the early stages of fruit growth, then declined temporarily. At fruit maturity, the content of Ca and K in branches was the highest, while the content of Ca and N in leaves was the highest. At fruit maturity, the average nutrient content of N, P, K, Ca, Mg, Fe, Mn, Cu, and Zn in the branches and leaves were 17.25 g/kg, 1.99 g/kg, 18.84 g/kg, 26.14 g/kg, 3.69 g/kg, 215.61 mg/kg, 248.85 mg/kg, 13.08 mg/kg, and 53.77 mg/kg. The N, K, Ca, Fe, Cu, and Zn content in the branches and leaves significantly correlated with those nutrients content in the soil. Discussion: The appropriate period for nutrient diagnosis of Z. bungeanum is 39−86 d after flowering (AF), with the critical period for branch and leaf nutrient requirements being 1−39 d AF. This provides a basis for nutrient supplements in Z. bungeanum 'Hanyuan' orchards management. [ABSTRACT FROM AUTHOR]

Litter decomposition is critical for maintaining productivity and nutrient cycling in forest ecosystems. Large herbivores play an essential role in determining the processes of nutrient cycling. Asian temperate forests are becoming degraded and fragmented by the widespread intensification of anthropogenic activities, including excessive livestock grazing. However, the effects of livestock grazing and wild ungulates on forest litter decomposition remain less explored. In this study, we used a litterbag experiment to investigate the effects of the addition of cattle (Bos taurus) and sika deer (Cervus nippon) feces on litter decomposition. The study was conducted in Northeast China from July 2022 to October 2023. We found that the addition of deer feces significantly reduced litter decomposition, but the addition of cattle feces greatly increased litter decomposition. The presence of cattle and deer excrement significantly accelerated the release of C after 1 year of litter decomposition. Compared with the results of the control group (no addition of feces), the addition of cattle and sika deer feces increased C release by 37.45% and 22.69%, respectively. Fecal addition increased the release of N; however, for the three treatment groups, the maximum accumulation of N occurred in the middle of litter decomposition, which may have been due to the initial chemical quality of the leaves and snow melt as well as nutrient limitations at the sites. Compared with the results of the control group, P release in the feces of cattle increased by 4.35%, but P release in the feces of deer decreased by 27.55%. This work highlights that feces deposition by large herbivores (e.g., wild or domestic) in the forest has nonequivalent effects on litter decomposition. Such effects may further alter the nutrient cycling in temperate forest ecosystems, with far‐reaching effects on the ecosystem that deserve closer attention. We suggest that conservation managers should seek evidence‐based interventions to optimize livestock use of forest habitats shared with wildlife. [ABSTRACT FROM AUTHOR]

A topography change in the continental plain plays an important role in nutrient replenishment mechanisms in oligotrophic oceans. Effects of the topography on the nutrient distribution in the western South China Sea (WSCS) have been overlooked since most studies have focused on the dipole‐induced upwelling and downwelling processes of nutrients. We hypothesize that the seamount topography in the northwestern side of the WSCS contributes to the upward distribution of nutrients. We conducted a cruise to investigate the vertical distribution of nutrients in a large area where there is a gradient in the topography: shallow in the north to deep in the south. Our results showed that the depth contours of nutrients, temperature, and salinity shoaled upward from deep to shallow with their isolines being parallel to the bottom depth. The depth of mixed layer, pycnocline, nutricline, and deep chlorophyll maximum showed the similar topographic effect. In the deep water column of 4,308 m deep, integrated NO3− and PO43– over 0–200 m were 879.60 and 81.78 mmol m−2, but increased to 2010.17 and 143.79 mmol m−2 in the shallow water column of 930 m deep, respectively. The increased supply of nutrients enhanced 0–200 m integrated chlorophyll from 21.71 mg m−2 in the deep water column to 51.51 mg m−2 in the shallow water column. These results demonstrate that topographic elevations such as seamounts induce deep‐to‐shallow shoaling and upwelling that lead to enhanced nutrients and biological production in the euphotic zone of oligotrophic oceans. Plain Language Summary: The supply of nutrients from deep water to the euphotic zone is a very important source of nutrients for maintaining primary productivity in marine ecosystems. Seamounts as elevations of the topography from seabed play a significant role in shaping currents and regulating nutrients in the oceans. However, the effects of topography on biogeochemical processes in the western South China Sea (WSCS) have been overlooked. We conducted a cruise to investigate the nutrient dynamics along with the changing of topography in the WSCS. We found that the isolines of nutrients, temperature, and salinity were parallel to the bottom depth, showing low nutrients in the deeper southeastern region and high nutrients in the shallower northwestern region. Additionally, the water column structures such as the depth of mixed layer, pycnocline, and nutricline were significantly correlated with bottom depths. The nitrate and phosphate stocks in the 0–200 m water column of shallow area were 2.3 and 1.8 times of that in deep area, respectively. Furthermore, the increased supply of nutrients in shallow water enhanced chlorophyll stocks from 21.71 to 51.51 mg m−2. The results demonstrated that the topography‐induced upwelling of deep water leads to enhanced nutrients and primary production in the oligotrophic oceans. Key Points: Topographic elevations in northwestern part of western South China Sea induce the upwelling of deep water and enhance the chlorophyllShoaling of deep water contributes to the dynamics of nutrients, salinity, and temperature in the northern eddy of the dipole [ABSTRACT FROM AUTHOR]

Bioturbation (sediment disturbance by animal actions) effects on nutrient cycling and nutrient levels in surface waters are difficult to quantify, in part because the diversity and magnitude of species‐specific influences are poorly understood. These influences may have consequences for the management of the trophic state of freshwater ecosystems. Fish cause bioturbation in freshwater and marine ecosystems by digging in benthic sediments, manipulating periphyton mats while searching for prey and scraping hard substrates while feeding. We used experimental enclosures (2.25 m2) to quantify bioturbation‐mediated phosphorus (P) and nitrogen (N) regeneration from sediment by three species of fish that differ in interactions with the benthos (largemouth bass, Micropterus salmoides; tilapia, Oreochromis spp.; and sailfin catfish, Pterogoplichthys spp.) in shallow eutrophic wetlands in Southern Florida. Tilapia are omnivores that include detritus in their diet (winnowing or ingesting sediments) and dig nests in soft sediments year round, sailfin catfish actively burrow into substrate and consume detritus (digging and ingesting sediments), and largemouth bass are piscivores that do not routinely interact with the benthos when feeding but may dig nests in soft sediment in spawning season (January–April). We quantified the amount of suspended flocculent organic matter and changes in water column nutrients (total phosphorus [TP] and total nitrogen [TN]) in 2‐week trials for each species and estimated the portion of nutrient increases relative to fishless controls that could be attributed to bioturbation‐mediated internal nutrient loading through suspension of organic matter (as opposed to excretion or other sources of nutrient loading). Water column nutrient concentrations increased with increasing biomass for all species, but the bioturbation contribution differed by species. Largemouth bass increased water column nutrient concentrations (TP: 86% and TN: 5% relative to controls) but did not influence water column suspended particulate matter through bioturbation of sediment. Tilapia increased water column nutrients a modest amount (TP: 8%; TN: 15%), of which a small portion was attributed to bioturbation (c. 18% of TP). Sailfin catfish raised water column nutrients substantially (TP: 105%; TN: 46%) and up to 100% of the increased TP was attributed to bioturbation. Sailfin catfish also suppressed algal growth and TP accumulation on the sides of the enclosures and reduced nutrient concentrations of the flocculent sediments. Our results were consistent with our hypothesis that behaviour and foraging traits affect bioturbation contributions to nutrient loading. The results also demonstrated that species with similar net effects like largemouth bass and sailfin catfish, added nutrients via different mechanisms (i.e. excretion vs. bioturbation). Considering the feeding strategies and interactions with the substrate of common fish species may assist managers in meeting nutrient reduction goals for eutrophic wetlands and managed freshwater systems. [ABSTRACT FROM AUTHOR]

Marine pollution poses significant risks to both human and marine health. This investigation explores the limnological status of the Odisha and West Bengal coasts during the annual cruise program, focusing on the influence of riverine inputs on coastal marine waters. To assess this impact, physicochemical parameters such as pH, salinity, total suspended solids (TSS), dissolved oxygen (DO), biochemical oxygen demand (BOD), and dissolved nutrients (NO2-N, NO3-N, NH4-N, PO4-P, SiO4-Si, total-N, and total-P) were analyzed from samples collected along 11 transects. Multivariate statistics and principal component analysis (PCA) were applied to the datasets, revealing four key factors that account for over 70.09% of the total variance in water quality parameters, specifically 25.01% for PC1, 21.94% for PC2, 13.13% for PC3, and 9.99% for PC4. The results indicate that the increase in nutrient and suspended solid concentrations in coastal waters primarily arises from weathering and riverine transport from natural sources, with nitrate sources linked to the decomposition of organic materials. Coastal Odisha was found to be rich in phosphorus-based nutrients, particularly from industrial effluents in Paradip and the Mahanadi, while ammonia levels were attributed to municipal waste in Puri. In contrast, the West Bengal coast exhibited higher levels of nitrogenous nutrients alongside elevated pH and DO values. These findings provide a comprehensive understanding of the seasonal dynamics and anthropogenic influences on coastal water quality in Odisha and West Bengal, highlighting the need for targeted conservation and management efforts. [ABSTRACT FROM AUTHOR]

To advance environmentally friendly technologies in the aquaculture of Atractoscion nobilis, and simultaneously to diversify seafood production, a 79-day trial was conducted to assess the performance of Ulva lactuca and Devaleraea mollis cultured in the effluent from A. nobilis in a land-based integrated multi-trophic aquaculture (IMTA) system in southern California, USA. Water quality and performance of macroalgae were measured weekly. The impacted factors on the growth of macroalgae and nutrient uptake rate of macroalgae were assessed. The specific growth rate of juvenile A. nobilis was 0.47–0.52%/d. Total ammonia nitrogen in effluents of A. nobilis tanks ranged from 0.03 to 0.19 mg/L. Ulva lactuca and D. mollis achieved an average productivity of 24.53 and 14.40 g dry weight (DW)/m2/d. The average nitrogen content was 3.48 and 4.89% DW, and accordingly, the average nitrogen uptake rate was 0.88 and 0.71 g/m2/d, respectively. Temperature and nutrient concentration were key factors impacting macroalgae growth, and light intensity also impacted the growth of D. mollis. The high protein content of U. lactuca and D. mollis would make them good for use as human or animal food, or for use in other industries. Research on the interaction effects between seawater exchange rates and aeration rates on the performance and nutrient uptake rates of macroalgae will be conducted in future studies. [ABSTRACT FROM AUTHOR]

ABSTRACT Modern runner-type peanut cultivars have high yield potential, but little is still known about the dynamics of nutrient uptake by these cultivars and whether nutrient uptake differs between maturity groups. This study evaluated the growth, nutrient uptake, and nutrient removal of runner-type peanut cultivars with early and late maturity. The study was conducted in the field in the 2021/2022 season, in a sandy soil environment in southeastern Brazil. Treatments consisted of runner-type peanut cultivars (early and late maturity) and the phenological stage of sampling (V4/V5, R2/R3, R4, R5, R6, R7, and R8). Average pod yields were 4.0 and 5.9 Mg ha-1 for the early and late-maturity cultivars, respectively. Uptake of P, Cu, and Zn was linearly increased until stage R8. Nitrogen uptake continued until stage R7 for the early-maturity cultivars and stage R8 for the late-maturity cultivar. Potassium and B uptake did not increase after stages R5 and R6, respectively. For all other nutrients, maximum uptake occurred between stages R3 and R7. Leaf contents of all nutrients were within the sufficiency range, except Fe, which was higher than needed. Maximum macronutrient uptake (late-maturity cultivar) rates were 300, 28, 215, 76, 31, and 19 kg ha-1 for N, P, K, Ca, Mg, and S, respectively, and the maximum micronutrient uptake rates were 2350, 95, 391, 659, and 414 g ha-1 for Fe, Cu, Zn, Mn, and B, respectively. Maximum macronutrient removal rates were 210, 20, 48, 15, 7, and 12 kg ha-1 for N, P, K, Ca, Mg, and S, respectively, and the maximum micronutrient removal rates were 967, 59, 236, 153, and 136 g ha-1 for Fe, Cu, Zn, Mn, and B, respectively. Late-maturity cultivar had higher biomass production and greater uptake of all nutrients except K and Fe. The uptake of K and Fe was the same for both maturity groups.

The Asan Wetland is an important freshwater wetland in Uttarakhand’s Dehradun district. It is known for its diverse flora and fauna and as a stopover for migratory birds. Periphyton, an essential biological component of aquatic ecosystems, serves as a bioindicator of water quality and ecosystem integrity. This study fills a gap in our knowledge of the Asan Wetland’s ecological health by analyzing periphyton populations and a number of physicochemical characteristics across three selected sites from November 2021 to October 2023. Selected sites named as Site 1(S1), Site 2(S2), Site 3 (S3). Monthly variations in parameters such as water temperature, pH, turbidity, transparency, total dissolved solids (TDS), electrical conductivity, dissolved oxygen (DO), total hardness, alkalinity, biological oxygen demand (BOD), chemical oxygen demand (COD), and nutrients were collected, identified and assessed using Ms-excel and Past software. Phosphorus levels in the Asan Wetland indicated a moderate to high nutrient load, peaking in August (1.20–1.25 mg/L) across all three sites and dropping to their lowest in January (0.35–0.65 mg/L). Nitrate levels were moderate, with the highest concentrations in December (1.40–1.55 mg/L) and the lowest in July (0.25–0.35 mg/L), showing similar seasonal patterns across sites. The periphyton was represented in this study by 18 different periphytic taxa that belong to three different classes. These classes include Bacillariophyceae (Cymbella, Navicula, Nitzschia, Fragilaria Meridion, Synedra, Gomphonema, Tabellaria, and Diatoma), members of the Chlorophyceae Ulothrix, Spirogyra, Cosmarium, Microspora, Chlorella, Oedogomium, Zygnema, and Cladophora are, while Phormidium is a member of the Cyanophyceae. The peak periphytic density (individuals/cm2) recorded was 322.67 ± 89.08 × 103 in January, with all three classes exhibiting maximum values at S3, the minimum periphytic density (individuals/cm2) recorded was 18 ± 5.57 × 10³ in August. The annual percentage composition of periphytic flora in the Asan wetland over 2 years indicates that Bacillariophyceae constituted the predominant group (89%–90%), succeeded by Chlorophyceae (7%–9%) and Cyanophyceae or Myxophyceae (1%–4%) across three sites. The canonical correspondence analysis (CCA) of periphyton among different sites during both years of the study suggested that S3 was more diverse, followed by S1 and S2, represented 64.93%, 35.07% of the variance with eigenvalues of 0.01794, 0.00968 respectively. PCA suggested that PC1 and PC2 were represented by 93.98% and 6.015% of the variance with eigenvalues 279.149 and 17.8675, respectively The multivariate cluster analysis showed the similarity of periphyton at three different sites during the 2-year study. The findings of this study emphasize the need for targeted management strategies to maintain the ecological health of the Asan Wetland.

This scholarly study investigated the physicochemical characteristics of soil in the Al-Jabal Al-Akhdar forest, Libya, with a specific focus on the influence of elevation and slope aspects. Fifty-six sample plots were established across varying elevations, each subdivided into four subplots, totaling 224. Soil samples were collected from each subplot at 0-15 cm depth. Results demonstrate significant variations in clay, silt, and sand content with elevation, indicating lower clay and higher sand content at higher elevations. Available water capacity (AWC) increased with altitude on the northern slope, while consistently lower values were observed on the southern slope. Bulk density (BD) decreased with increasing altitude, suggesting less compacted soils at higher elevations. Available phosphorus (Pav), available potassium (Kav), and pH values decreased with increasing altitude on both slopes. Cation exchange capacity (CEC) values varied at altitudes on the northern slope, with higher values observed at mid to high altitudes. Calcium carbonate (CaCO3) decreased with increasing altitude on the northern slope while showing inconsistent trends on the southern slope. Soil organic matter (SOM) content increased with altitude on both slopes. Pearson's correlation and Principal Component Analysis (PCA) examined relationships among soil properties, elevations, and aspects. Elevation positively correlated with AWC and SOM and negatively correlated with clay content, Kav, BD, and pH. PCA identified elevation, aspect, silt content, CaCO3, and electrical conductivity (EC) as primary influencers. SOM exhibited positive correlations with AWC and negative correlations with BD. Soil pH showed a negative correlation with SOM and a positive correlation with CaCO3. Additionally, CaCO3 content was positively correlated with the cation exchange capacity (CEC). These findings contribute to understanding soil property relationships, elevation, and aspect, emphasizing their role in shaping soil ecosystems and nutrient dynamics. Further research is warranted to explore additional factors influencing soil properties and to develop effective nutrient management strategies.

Introduction: Oilseed flax (Linum usitatissimum L.) yields are phosphate (P) fertilizer-limited, especially in the temperate semiarid dryland regions of North China. However, there are limited studies on the effects of P-fertilizer inputs on plant growth and soil microorganisms in flax planting systems. Methods: To address this gap, a field experiment was conducted with four treatments: no P addition and application of 40, 80, and 120 kg P ha-1, respectively. The aim was to investigate the influence of various P fertilizer inputs on yield, plant dry matter, P use efficiency, as well as the population of soil arbuscular mycorrhizal fungi (AMF) and bacteria in dryland oilseed flax. Results: Our results show that the P addition increased the dry matter, and the yield of oilseed increased by ~200% at 120 kg P ha-1 addition with inhibition on the growth of AMF hyphae. The moderate P supply (80 kg ha-1) was adequate for promoting P translocation, P use efficiency, and P recovery efficiency. Soil pH, available P, and available K significantly (p< 0.05) promoted the abundance of the dominant taxa (Acidobacteria_GP6, Sphingobacteria and Bacteroidetes). In addition, it is imperative to comprehend the mechanism of interaction between phosphorus-fertilizer inputs and microbiota in oilseed flax soil. Discussion: This necessitates further research to quantify and optimize the moderate phosphorus supply, regulate soil microbes to ensure high phosphorus utilization, and ultimately establish a sustainable system for oilseed flax cultivation in the local area. [ABSTRACT FROM AUTHOR]

While the biogeochemical properties of the Israeli coastal shelf (ICS) are similar to adjacent pelagic waters, the external sources of inorganic nitrogen (N) are very different. The main source of 'new' N to the pelagic zone is deep winter mixing, with minor contributions from atmospheric deposition and eddy diffusion across the nutricline. For the ICS, major N sources include offshore water advection (260 × 10⁶ mol N y−¹), atmospheric input (115 × 10⁶ mol N y−¹), and riverine input (138 × 10⁶ mol N y−¹), which primarily consists of treated wastewater and stormwater runoff. Direct pollutant discharge from sewage outfalls and submarine groundwater discharge are relatively minor. Key N sinks are new production (420 × 10⁶ mol N y−¹) and sediment deposition and uptake (145 × 10⁶ mol N y−¹). Inputs of nitrate and ammonium were similar and dominant in winter. Unlike temperate shelves, where riverine input is dominant, here it was only slightly higher than atmospheric input, with net N advection onto the shelf being significant. External N inputs did not change net primary production (NPP) by more than ~30% or affect dominant pico and nanophytoplankton genera, except in localized patches. This study offers baseline values for future climate and environmental change assessments. [ABSTRACT FROM AUTHOR]

Green gram is an excellent pulse crop with high economic and nutritional values. Optimal water and nutrient application can boost yield, water productivity, nutrient use, energy indices, and economic gains. The field experiment comprising three irrigation schedules (one irrigation at pre-flowering, two irrigations at pre-flowering and pod formation, and three irrigations at branching, pre-flowering and pod formation stages) and four nutrient management (control, 100% recommended fertilizer (RDF), farmyard manure at 5 t ha−1, and 100% RDF + FYM at 5 t ha−1) was arranged in a split-plot design with three replications during the summer seasons of 2016 and 2017. Based on the principal component analysis technique and economic assessment of all the treatments studied, three irrigations at branching, pre-flowering and pod formation stages with the recommended fertilizer plus FYM resulted in the maximum growth, yield components, seed yield (784 kg ha−1), stover yield (2288 kg ha−1), highest NPK uptake, total output energy, net energy gain, greatest gross return (USD 749.7 ha−1), net return (USD 331.7 ha−1) and higher BCR (1.79). However, maximum crop water productivity and irrigation water productivity (0.55 and 0.96 kg m−3, respectively) were recorded with a single irrigation at pre-flowering stage in tandem with full recommended fertilizer and farmyard manure. A linear relationship was detected between seed yield and seasonal crop evapotranspiration (ETc) at different nutritional levels. Seasonal water consumtion of 178 mm corresponding to an irrigation amount of 170 mm with a yield of 620 kg ha−1 and CWP of 0.36 kg m−3 was a balance for optimum seed yield, ETc and CWP. The 0–30 cm depth of the root zone profile contributed 80–84% while the 30–60 cm depth accounted for 16–20% of total soil moisture depletion. Based on the physical and financial outputs, a three-irrigation schedule coupled with the full recommended fertilizer and manure was identified as the best management strategy for green gram production and can thus be recommended to farmers of non-saline coastal soils in eastern India. [ABSTRACT FROM AUTHOR]

Background: The dynamics of carbon (C), nitrogen (N), and phosphorus (P) in soils determine their fertility and crop growth in agroecosystems. These dynamics depend on microbial metabolism, which in turn depends on nutrient availability. Farmers typically apply either mineral or organic fertilizers to increase the availability of nutrients in soils. Phosphorus, which usually limits plant growth, is one of the most applied nutrients. Our knowledge is limited regarding how different forms of P impact the ability of microbes in soils to produce the enzymes required to release nutrients, such as C, N and P from different substrates. Methods: In this study, we used the arable layer of a calcareous soil obtained from an alfalfa cropland in Cuatro Cienegas, México, to perform an incubation experiment, where five different phosphate molecules were added as treatments substrates: three organic molecules (RNA, adenine monophosphate (AMP) and phytate) and two inorganic molecules (calcium phosphate and ammonium phosphate). Controls did not receive added phosphorus. We measured nutrient dynamics and soil microbial activity after 19 days of incubation. Results: Different P molecules affected potential microbial C mineralization (CO2-C) and enzyme activities, specifically in the organic treatments. P remained immobilized in the microbial biomass (Pmic) regardless of the source of P, suggesting that soil microorganisms were limited by phosphorus. Higher mineralization rates in soil amended with organic P compounds depleted dissolved organic carbon and increased nitrification. The C:N:P stoichiometry of the microbial biomass implied a change in the microbial community which affected the carbon use efficiency (CUE), threshold elemental ratio (TER), and homeostasis. Conclusion: Different organic and inorganic sources of P affect soil microbial community structure and metabolism. This modifies the dynamics of soil C, N and P. These results highlight the importance of considering the composition of organic matter and phosphate compounds used in agriculture since their impact on the microbial activity of the soil can also affect plant productivity. [ABSTRACT FROM AUTHOR]

Extreme precipitation and flooding frequency associated with global climate change are expected to increase worldwide, with major consequences in floodplains and areas susceptible to flooding. The purpose of this review was to examine the effects of flooding events on changes in soil properties and their consequences on agricultural production. Flooding is caused by natural and anthropogenic factors, and their effects can be amplified by interactions between rainfall and catchments. Flooding impacts soil structure and aggregation by altering the resistance of soil to slaking, which occurs when aggregates are not strong enough to withstand internal stresses caused by rapid water uptake. The disruption of soil aggregates can enhance soil erosion and sediment transport during flooding events and contribute to the sedimentation of water bodies and the degradation of aquatic ecosystems. Total precipitation, flood discharge, and total water are the main factors controlling suspended mineral-associated organic matter, dissolved organic matter, and particulate organic matter loads. Studies conducted in paddy rice cultivation show that flooded and reduced conditions neutralize soil pH but changes in pH are reversible upon draining the soil. In flooded soil, changes in nitrogen cycling are linked to decreases in oxygen, the accumulation of ammonium, and the volatilization of ammonia. Ammonium is the primary form of dissolved inorganic nitrogen in sediment porewaters. In floodplains, nitrate removal can be enhanced by high denitrification when intermittent flooding provides the necessary anaerobic conditions. In flooded soils, the reductive dissolution of minerals can release phosphorus (P) into the soil solution. Phosphorus can be mobilized during flood events, leading to increased availability during the first weeks of waterlogging, but this availability generally decreases with time. Rainstorms can promote the subsurface transport of P-enriched soil particles, and colloidal P can account for up to 64% of total P in tile drainage water. Anaerobic microorganisms prevailing in flooded soil utilize alternate electron acceptors, such as nitrate, sulfate, and carbon dioxide, for energy production and organic matter decomposition. Anaerobic metabolism leads to the production of fermentation by-products, such as organic acids, methane, and hydrogen sulfide, influencing soil pH, redox potential, and nutrient availability. Soil enzyme activity and the presence of various microbial groups, including Gram+ and Gram− bacteria and mycorrhizal fungi, are affected by flooding. Waterlogging decreases the activity of β-glucosidase and acid phosphomonoesterase but increases N-acetyl-β-glucosaminidase in soil. Since these enzymes control the hydrolysis of cellulose, phosphomonoesters, and chitin, soil moisture content can impact the direction and magnitude of nutrient release and availability. The supply of oxygen to submerged plants is limited because its diffusion in water is extremely low, and this impacts mitochondrial respiration in flooded plant tissues. Fermentation is the only viable pathway for energy production in flooded plants, which, under prolonged waterlogging conditions, is inefficient and results in plant death. Seed germination is also impaired under flooding stress due to decreased sugar and phytohormone biosynthesis. The sensitivity of different crops to waterlogging varies significantly across growth stages. Mitigation and adaptation strategies, essential to the management of flooding impacts on agriculture, enhance resilience to climate change through improved drainage and water management practices, soil amendments and rehabilitation techniques, best management practices, such as zero tillage and cover crops, and the development of flood-tolerant crop varieties. Technological advances play a crucial role in assessing flooding dynamics and impacts on crop production in agricultural landscapes. This review embarks on a comprehensive journey through existing research to unravel the intricate interplay between flooding events, agricultural soil, crop production, and the environment. We also synthesize available knowledge to address critical gaps in understanding, identify methodological challenges, and propose future research directions. [ABSTRACT FROM AUTHOR]

Shallow coastal lagoons with restricted connection to the ocean are often productive but can also be sensitive to nutrient enrichment and hydrologic changes. Resolving nutrient dynamics is important for their sustainable management, yet being able to accurately resolve nutrient budgets has remained a challenge due to their complex hydrological regimes and habitat heterogeneity. In this study, we undertake a systematic nutrient budget of a large shallow hypersaline lagoon (Coorong, South Australia), with assistance of a high‐resolution coupled hydrodynamic‐biogeochemical model, to demonstrate the conditions that lead to nutrient retention. Under current conditions, high rates of evapo‐concentration and limited water connectivity have led to a persistent accumulation of nutrients and poor water quality in substantial areas of the lagoon. The interplay between hydrological drivers and biogeochemical processes was quantified using an adjusted Damköhler number, comparing the timescales of nutrient flushing versus processing. This showed a general transition from hydrologic control to biogeochemical control with increasing distance from the main ocean connection, modified by episodes of increased flows and external loads. Whilst water age was a useful indicator of the factors controlling rates of nutrient retention, interannual variability in retention between areas of the lagoon was explained based on river flows and changes in mean sea level. As the system has been affected by reduced flows over past decades, the results provide evidence that increasing river flow to the lagoon would reduce the nutrient retention, and we discuss the potential for net nutrient export to the ocean under sustained high flows. Plain Language Summary: Nutrient loads to coastal waters have increased worldwide as a direct consequence of the growing human population and increased development, with the end result being degraded water quality. Coastal lagoons with topographically restricted connection to the ocean are particularly sensitive relative to other coastal ecosystems since poor flushing and evaporation promotes nutrient retention. Resolving processes and factors that "control" nutrient concentrations is therefore important for guiding water quality management and ecosystem restoration. We studied nutrient dynamics in the Coorong, a shallow hypersaline coastal lagoon located in South Australia, using a high‐resolution coupled hydrodynamic‐water quality model. We showed that reducing flows to the system, and low mean sea level anomalies, encourage increased nutrient recycling and retention within the lagoon, resulting in persistent accumulation of nutrients in the south lagoon where water quality has become degraded. Based on the results, we conclude that potential restoration measures must focus on increasing hydrologic control through managing flow volumes and/or ocean flushing in order to optimize nutrient export. Key Points: An adjusted Damköhler number was developed to quantitatively compare hydrologic versus biogeochemical controls on nutrient dynamicsA transition from hydrologic control to biogeochemical control with increasing water retention time led to higher nutrient retention ratesAnnual nutrient retention rates were co‐modulated by catchment inflows and mean sea levels [ABSTRACT FROM AUTHOR]

Forest litter decomposition is vital for nutrient cycling and carbon turnover. To investigate their decomposition rate, we conducted a litter bag experiment in plantation forests (PF) and natural forests (NF) in a subtropical ecosystem. Our findings showed significant seasonal variation in litter mass loss (p

IntroductionThe dynamic changes of mineral nutrients in the leaf and branch of Zanthoxylum bungeanum ‘Hanyuan’ during fruit development can serve as a basis for nutrient diagnosis and scientific fertilization.MethodsThe content of Nitrogen (N), phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), iron (Fe), manganese (Mn), copper (Cu), and zinc (Zn) in the branch and leaf were measured using current-year shoots of 10-year-old Z. bungeanum ‘Hanyuan’ during the fruit development period, and the corresponding nutrient content in soil of the orchard were also determined to explore the nutrient demand patterns of Z. bungeanum ‘Hanyuan’ trees.ResultsBoth branch and leaf exhibited relatively high levels of various nutrients during the early stages of fruit growth, then declined temporarily. At fruit maturity, the content of Ca and K in branches was the highest, while the content of Ca and N in leaves was the highest. At fruit maturity, the average nutrient content of N, P, K, Ca, Mg, Fe, Mn, Cu, and Zn in the branches and leaves were 17.25 g/kg, 1.99 g/kg, 18.84 g/kg, 26.14 g/kg, 3.69 g/kg, 215.61 mg/kg, 248.85 mg/kg, 13.08 mg/kg, and 53.77 mg/kg. The N, K, Ca, Fe, Cu, and Zn content in the branches and leaves significantly correlated with those nutrients content in the soil.DiscussionThe appropriate period for nutrient diagnosis of Z. bungeanum is 39−86 d after flowering (AF), with the critical period for branch and leaf nutrient requirements being 1−39 d AF. This provides a basis for nutrient supplements in Z. bungeanum ‘Hanyuan’ orchards management.

Coastal eutrophication is a major issue of marine pollution. The main factors controlling eutrophication must be identified to ensure effective marine environmental management according to the respective local conditions. Zhanjiang Bay (ZJB), located northwest of the South China Sea, is a semi-closed bay influenced by complex water flows and the development of surrounding cities. In this study, we investigated the development of nutrient concentrations and compositions in ZJB seawater over the past 20 years and the factors influencing eutrophication based on several field investigations from 2006 to 2022 and historical data. High concentrations of dissolved inorganic phosphorus (DIP) and dissolved inorganic nitrogen (DIN) were the main contributors to the severe long-term eutrophication in ZJB; however, light eutrophication was observed in the outer bay, primarily caused by chemical oxygen demand (COD) and DIP. The primary sources of COD and nutrients were riverine freshwater, sewage outfalls, mariculture and domestic effluents carried by rivers. Tidal effects diluted the nutrient concentrations in the bay with seawater from the outer bay, thereby playing a key role in nutrient redistribution. The DIN: DIP ratio of ZJB showed long-term nitrogen restriction and excess phosphorus, primarily owing to mariculture activities. Marine undertakings can exert various impacts on water quality. Eliminating illegal aquaculture and launching aquaculture tailwater treatment can improve water quality, whereas practices such as channel dredging may worsen it. This study demonstrates the intricate dynamics of the ZJB ecosystem and offers valuable insights for effective environmental management and conservation efforts. [ABSTRACT FROM AUTHOR]

Summary: Species‐specific differences in nutrient acquisition strategies allow for complementary use of resources among plants in mixtures, which may be further shaped by mycorrhizal associations. However, empirical evidence of this potential role of mycorrhizae is scarce, particularly for tree communities.We investigated the impact of tree species richness and mycorrhizal types, arbuscular mycorrhizal fungi (AM) and ectomycorrhizal fungi (EM), on above‐ and belowground carbon (C), nitrogen (N), and phosphorus (P) dynamics.Soil and soil microbial biomass elemental dynamics showed weak responses to tree species richness and none to mycorrhizal type. However, foliar elemental concentrations, stoichiometry, and pools were significantly affected by both treatments. Tree species richness increased foliar C and P pools but not N pools. Additive partitioning analyses showed that net biodiversity effects of foliar C, N, P pools in EM tree communities were driven by selection effects, but in mixtures of both mycorrhizal types by complementarity effects. Furthermore, increased tree species richness reduced soil nitrate availability, over 2 yr.Our results indicate that positive effects of tree diversity on aboveground nutrient storage are mediated by complementary mycorrhizal strategies and highlight the importance of using mixtures composed of tree species with different types of mycorrhizae to achieve more multifunctional afforestation. [ABSTRACT FROM AUTHOR]

Effective nutrient management necessitates monitoring of nutrient requirement, extent and timing of nutrient supply during the fruit development. To achieve a good nutrient balance and its impact on fruit quality, study of nutrient dynamics is of utmost importance as it provides an intriguing stratagem to control tree nutrient status. The research aimed at investigating seasonal patterns of nutrient concentrations in leaves and fruits of apple (Malus × domestica Borkh.) cv Silver Spur on various clonal rootstocks (MM106, M4 and M9) during the year 2019–2020 and their impact on fruit quality. For this purpose collection of leaf and fruit samples commenced from one month after full bloom (May 15) until harvesting (September 18) at an interval of twenty one days and samples were evaluated for both macro and micro-nutrients {Nitrogen (N), Phosphorus (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Boron (B)} and quality characteristics. In general, concentration of N, P, K and B declined continuously in both leaf and fruit toward the end of fruit maturation, whereas leaf Ca and Mg augmented along the cycle, however fruit Ca and Mg increased up to first fruit development stage and then decreased again signifying nutrient dilution along growing season and its effect on fruit quality. With respect to rootstocks, semi-vigorous rootstock MM106 recorded higher values for leaf and fruit nutrient concentrations as compared to dwarf M9 and semi-dwarf M4 rootstocks specifying a significant effect of rootstocks on nutrient absorption. [ABSTRACT FROM AUTHOR]

Rewetting drained agricultural peatlands aids in restoring their original ecosystem functions, including carbon storage and sustaining unique biodiversity. 30–60 cm of topsoil removal (TSR) before rewetting for Sphagnum establishment is a common practice to reduce nutrient concentrations and greenhouse gas emissions, and increase water conductivity. However, the topsoil is carbon-dense and preservation in situ would be favorable from a climate-mitigation perspective. The effect of reduced TSR on Sphagnum establishment and nutrient dynamics on degraded and rewetted raised bogs remains to be elucidated. We conducted a two-year field experiment under Sphagnum paludiculture management with three TSR depths: no-removal (TSR0), 5–10 cm (TSR5), and 30 cm (TSR30) removal. We tested the effects of TSR on Sphagnum establishment and performance, nutrient dynamics, and hotspot methane emissions. After two years, TSR5 produced similar Sphagnum biomass as TSR30, while vascular plant biomass was highest in TSR0. All capitula nitrogen (N > 12 mg/g) indicated N-saturation. Phosphorus (P) was not limiting (N/P < 30), but a potential potassium (K) limitation was observed in year one (N/K > 3). In TSR0, ammonium concentrations were > 150 µmol/l in year one, but decreased by 80% in year two. P-concentrations remained high (c. 100 µmol/l) at TSR0 and TSR5, and remained low at TSR30. TSR30 and TSR5 reduced hotspot methane emissions relative to TSR0. We conclude that all TSR practices have their own advantages and disadvantages with respect to Sphagnum growth, nutrient availability and vegetation development. While TSR5 may be the most suitable for paludiculture, its applicability for restoration purposes remains to be elucidated. Setting prioritized targets when selecting the optimal TSR with peatland rewetting is pivotal. [ABSTRACT FROM AUTHOR]

Sediment-bound phosphorous fractions were analyzed to assess the bioavailability and trophic status of Thrissur Kole wetlands. Sequential extraction followed by spectrophotometry was employed for fractionation and determination of phosphate content in each fraction. Acid soluble organic phosphorous comprising of biological molecules was the most dominant fraction [278.02 ± 11.82 mg/kg (non-monsoon); 315.77 ± 13.84 mg/kg (monsoon)] recorded during both seasons and can be sourced to allochthonous as well as autochthonous sources. Elevated content of alkali soluble organic phosphorous [162.53 ± 14.85 mg/kg (non-monsoon); 307.22 ± 14.60 mg/kg (monsoon)] reflected leaching of humic-associated phosphorous from aquatic vegetation, domestic and municipal sewage. Enrichment of calcium-bound phosphorous was due to the abundance of calcium carbonate originating through biological precipitation and inputs from guano as well as carcass of birds. Enriched organic matter adsorbed on fine-grained sediments controls the retention of organic phosphorous through organic matter-iron-phosphorous association. Intense microbial reworking on organic matter (substantiated by depleted Eh values) resulted in a sharp decline in organic phosphorous fraction. Adsorption of iron/manganese oxyhydroxides was a prominent mechanism in the retention of phosphate in sediments, endorsed by multivariate statistical analysis. Alkaline pH and reducing environment promote the release of phosphate to the water column and hence bioavailability for phytoplankton uptake. Bioavailable phosphorous constitutes a major portion of total phosphorous [average: 606.86 ± 26.24 mg/kg (non-monsoon); 651.36 ± 23.05 mg/kg (monsoon)], which implied that the wetland sediments can function as a dynamic source of phosphate to the water column, signaling eutrophication risk. [ABSTRACT FROM AUTHOR]