Contents Of Available Nutrients Research Articles

Transport, pollution, and health risk of heavy metals in “soil-medicinal and edible plant-human” system: A case study of farmland around the Beiya mining area in Yunnan, China

Heavy metals (HMs) pose a significant threat to soil quality, plant growth, and human health. However, the impacts (transport, pollution, and health risk) of HMs in medicinal and edible plants with rich value growing in high background soil for a long time remain unclear. So the effects of HMs on the “soil-medicinal and edible plant-human” system were comprehensively studied. Houttuynia cordata Thunb. (HCT) and growing soil were collected from the farmland around Beiya mining area located in Three Parallel Rivers of Yunnan Protected Areas, China. The transport, pollution, and health risks of HMs in the system were investigated by determining the content of active ingredients, HMs, and physicochemical properties in HCT and soil. The results of comprehensive analysis using various measurement and analysis methods showed that Zn, Cu, Mn, and Co in soil could affect the contents of available nutrients (available P (AP), available K (AK), and organic matter (OM)), while AP, OM, pH, Co, and Fe in soil were closely related to the formation of HCT quality. Cr and Fe had the strongest transport capacity in stems and leaves of HCT, respectively. Furthermore, it is worth noting that Cr, Pb, and Cu had caused serious pollution to HCT in the area. Pb and Cu are tolerable levels for human health and may pose a carcinogenic risk. Our study demonstrates that HCT is expected to be a marker of heavy metal pollution in the area and provides a scientific basis for making effective regulations on HMs control and scientific planting.

Effects of Aviation Mutagenesis on Soil Chemical Indexes, Enzyme Activities, and Metabolites of Dahongpao (Camellia sinensis) Tea Trees.

Aviation mutagenesis is a breeding method for the rapid selection of superior plant varieties. In this study, rhizosphere soil chemical indexes, soil enzyme activities, and soil metabolites were measured in Dahongpao tea trees with aviation mutagenesis (TM) and without aviation mutagenesis (CK). The main soil metabolites distinguishing TM and CK and their relationships with soil chemical indexes and soil enzyme activities were analyzed and obtained. The results showed that there was no significant change in the rhizosphere soils' pH of TM tea trees compared to CK (p = 0.91), while all other chemical indexes of TM were significantly higher than CK (p < 0.05). In addition, the activities of enzymes related to soil nutrient cycling such as urease, protease, sucrase, acid phosphatase and cellulase, and enzymes related to soil antioxidants such as superoxide dismutase, catalase, peroxidase, and polyphenol oxidase were significantly increased (p < 0.05) in the rhizosphere soils of TM tea trees compared to CK. Soil metabolite analysis showed that the main soil metabolites distinguishing CK from TM were carbohydrates, nitrogen compounds, and amines. Of these, carbohydrates and nitrogen compounds were significantly positively correlated with soil chemical indexes and soil enzymes, whereas amine was significantly negatively correlated with soil chemical indexes such as organic matter, total nitrogen, total potassium, available nitrogen, available phosphorus; amine showed significant negative correlation with soil enzymes such as catalase, peroxidase, polyphenol oxidase, and urease. It can be seen that aviation mutagenesis is conducive to improving the ability of tea tree rhizosphere aggregation and transformation of soil nutrients, increasing the total amount of soil nutrients and the content of available nutrients, which is more conducive to promoting the uptake of nutrients by the tea tree, and thus promoting the growth of the tea tree.

Organic Materials Promote Rhododendron simsii Growth and Rhizosphere Soil Properties in a Lead-Zinc Mining Wasteland.

The mining of metal minerals generates considerable mining wasteland areas, which are characterized by poor soil properties that hinder plant growth. In this study, a field plot experiment was carried out in the mining wasteland of the Lanping lead-zinc mine in Yunnan Province to study the effects of applying three organic materials-biochar (B), organic fertilizer (OF), and sludge (S)-at concentrations of 1% (mass fraction), on promoting the soil of mining wasteland and the growth of two plant varieties (Huolieniao and Yingshanhong). The results showed that the amount of available nutrients in the surface soil of a mining wasteland could be considerably increased by S and OF compared to the control check (CK). In the rhizosphere soils of two Rhododendron simsii varieties, the application of S increased the available phosphorus (P) content by 66.4% to 108.8% and the alkali-hydrolyzed nitrogen (N) content by 61.7% to 295.5%. However, the contents of available cadmium (Cd) and available lead (Pb) were reduced by 17.1% to 32.0% and 14.8% to 19.0%, respectively. Moreover, three organic materials increased the photosynthetic rate and biomass of two R. simsii varieties. Specifically, OF and S were found to significantly increase the biomass of R. simsii. Organic materials have direct impacts on the increased plant height and biomass of R. simsii. Additionally, organic materials indirectly contribute to the growth of R. simsii by reducing the content of available Cd and available Pb in rhizosphere soil while increasing the content of available nutrients according to the structural equation model (SEM). Overall, S can stabilize Cd and Pb, increase soil nutrient contents, and promote the growth of R. simsii effectively, and has great potential in the vegetation reconstruction of mining wasteland.

The Effect of Applying Mineral Fertilizers Through Drip Irrigation and Furrow Method on the Movement of Mobile Nutrients in the Soil and the Growth, Development, and Accumulation of Nutrients in the Walnut Leaves

A task was set to reveal the effect of water-soluble fertilizers of new composition and quality on the content of available nutrients at different depths of the soil, depending on the movement of the irrigation water, irrigation time, as well as its effect on the growth, yielding capacity and the quality of fruit in commercial size walnut orchards. The research has shown that the movement of nutrients in the soil is completely dependent on the movement of water when applying water-soluble complex fertilizers with drip irrigation. Therefore, the amount of the water should be adjusted so that the nutrients are available to the plant’s root system at all depths, improving the growth, and increasing the content of the basic nutrients in the leaves.Fertilizers with less water-solubility are mainly preserved at a 0 cm - 30 cm depth. When the root system grows and spreads to the inter-row spaces, it is appropriate to periodically fertilize also the inter-row spacing by the furrow method.

Effect of simulated litterfall and sapling growth of invasive Quercus rubra and native Q. robur on soil in a pot experiment

Quercus rubra is an invasive species which can modify soil properties and change the structure and functions of the forest ecosystem. Its effect on soil physicochemical properties, including the content of nutrients (total and available) and phenolic compounds, was compared with that of native Quercus robur in a two-year pot experiment. Three treatments were applied to pots with soil: adding leaf litter (L), planting a sapling (S), and their combination (S + L). The litter was analyzed for its chemical composition before being added to the pots to determine whether it varied between species and whether this variation was reflected in the properties of L and S + L soils. The treatments were compared with the control, which consisted of soil-only pots, i.e., without litter and sapling. Both species increased the content of available nutrients (except N-NO3) and the content of phenolic compounds in the soil, with the former (namely N-NH4, P-PO4, and exchangeable K, Ca, and Mg) more affected by Q. robur and the latter (especially t-ferulic acid, myricetin, and quercetin) more affected by Q. rubra. Interestingly, this effect was pronounced for pots with saplings (S and S + L), while it was almost insignificant for pots with litter (L) only. When compared to the control, the treatments generally did not affect the total nutrient content in the soil. However, when comparing species, there was less total K and Mg under Q. rubra than under Q. robur saplings. The litter used in the experiment was significantly different between the two species. The Q. rubra leaves contained less N, P, K, Ca, total phenolics, and condensed tannins, and more organic C, (+)-catechin, ellagic acid, (–)-epicatechin, t-ferulic acid, kaempferol, and syringic acid than the leaves of Q. robur. However, since the effect of adding litter was negligible, these differences did not translate into differences in soil properties. Based on the obtained results, it is expected that the growth of invasive Q. rubra will result in worse soil conditions (less total and available nutrients and more phenolics) in the short term than the growth of native Q. robur in the same habitat. This means that planting Q. rubra outside its native range is associated with a risk of soil deterioration and, therefore, should be avoided, and the spontaneous dispersal of this species should be prevented.

Quantifying the fertility status and relationship between soil properties under major tea estates of North-western Himalaya

ABSTRACT Tea is being grown on the gentle slopes of Himachal Pradesh located in the north-western region of mighty Himalaya, since 1850s. However, degrading soil health due to rampant usage of agrochemicals, and long-run tea cultivation adversely affects the productivity potential of the region. Analyzing soil-nutrient status is of great value to meet the crop nutrient demand. The research aimed to identify the vulnerable soil properties and their assessment for soil restoration under major tea estates of the North-western Himalaya. The study examined the physico-chemical and biological properties of soils of 37 tea estates. The large variation among different sites for physical parameters signifies the textural difference between the sites under study. Meanwhile, the soil pH of tea estates varied from extremely acidic to slightly acidic reaction, with an overall pH (H2O) of 5.33 in the top soils and 5.47 in the subsoils. High OC (13.35 g kg−1) under overall soil depth of tea estates presumably correlated with higher concentration of available nutrients, i.e. N (r = 0.641), K (r = 0.492), and S (r = 0.623) alongside exchangeable Ca (r = 0.724) and Mg (r = 0.718). The substrate carbon availability due to higher amount of organic matter in the top soils (16.1 g kg−1) leads to increased biological activity (MBC and DHA) in the surface soils as compared to subsoils. The unscientific approach of fertilizer application led to huge variability in green leaf yield across different tea estates. Thus, to achieve higher yield, it should be necessary to adopt nutrient application in a judicial manner in the tea plantations.

Temporal-spatial variations of root and soil nutrient under continuous intercropping of alfalfa and oat

We investigated root and soil nutrient characteristics in the monoculture and continuous alfalfa/oat intercropping in the high-yield years by using soil filling and frame planting method in the field, and analyzed the relationship between root systems and soil nutrients. The results showed that intercropping reduced root weight and total root length proportion of oat in the 0-10 cm soil layer compared with the monoculture. However, intercropping significantly increased root weight and root surface area of oat in the 20-30 cm soil layer, root length and root density of alfalfa in the 10-20 cm soil layer, and the contents of available phosphorus and organic matter of the alfalfa/oat intercropping system in the 0-40 cm soil layer. As the planting years increased, total root length, root weight, root surface area, and proportion of root weight and root length of alfalfa in the 0-20 cm soil layer gradually increased in the intercropping system, and the root weight, total root length, root surface area, and root average diameter of oat increased, especially the root weight and root surface area of oat in the 20-30 cm soil layer. Moreover, the content of available nutrients in all soil layers decreased subsequently. In the alfalfa/oat intercropping system, continuous intercropping could significantly increase total root length of alfalfa in the 10-20 cm soil layer, improve root weight and root surface area of oat in the 20-40 cm soil layer (especially in the 20-30 cm soil layer). With the increases of planting years, intercropping intensified the absorption and competition of available nutrients by the roots of alfalfa and oat in the 0-40 cm soil layer, thereby reduced the accumulation of available nutrients in the soil.

Effect of Grasslands Fertilisation on Soil Organic Matter Quality and Nutrients Status

Abstract Soil organic matter (SOM) represents one of the largest and most important reservoirs of organic carbon in terrestrial eco-systems. The quality of SOM (e.g., content of soil organic carbon, humic substances, humic acids, fulvic acids, and HA/FA ratio) is a key factor in determining soil fertility and productivity. The loss of SOM is currently considered a detrimental form of soil degradation. The study aims to evaluate the effect of mineral fertilising (NPK), farmyard manure, cattle slurry, and digestate applications in intensively used permanent grassland. The long-term field experiments were carried out at the locality Jevíčko, region of Boskovice Furrow Malá Haná (the Czech Republic). The effect of amending soil with different organic and mineral fertilisers was studied. Qualitative parameters of SOM, soil reaction, and the content of available nutrients (N, P, K, Ca, Mg) were followed. Results showed that the control (no organic input) and the NPK variants had the lowest SOM quality. Higher SOM quality was after the farmyard manure, Slurry, and Digetsate applications. The highest acidity (indicated by the lowest values of pH/KCl) was determined in the control, NPK, Slurry, and D variants. The most favourable soil reaction and available nutrient content were after the farmyard manure application. Humic substances spectral absorption in the UV-VIS and infrared spectral ranges showed that the highest absorbance and amount of aliphatic hydrophobic components were observed after the application of farmyard manure. The multi-criteria statistical evaluation, including principal component analysis and factor analysis, confirmed that amending soil with farmyard manure and slurry resulted in an increase in humic substances content and improved SOM quality.

Impact of Paper Mill Effluent on Groundnut Root Nodulation and Soil Microorganisms for Inclusion of Compost

A Field experiment was conducted at Mondippatti village in Tiruchirappalli district of Tamil Nadu to study the effect of paper mill effluent irrigation with or without compost application on root growth, biological properties and soil nutrient status in Alfisol with groundnut as the test crop. The results revealed that the application of paper mill effluent along with compost favourably increased the soil nutrient status during the crop period. The highest concentrations of available nutrients viz., nitrogen, phosphorus, potassium, calcium, magnesium, sulphur, iron and zinc in the surface layer were 309.4 kg/ha, 14.2 kg/ha, 211.9 kg/ha, 64.9 meq/100g, 32.5 meq/100g, 38.8 mg/kg,11.4 mg/kg and 0.8 mg/kg, respectively in 75% paper mill effluent and press mud compost applications. Similarly, the use of paper mill effluent along with compost has a positive impact on soil microbial properties and highest population of bacteria was observed in 50% paper mill effluent and press mud application was 9.79 CFU (x106/g) followed by 100% paper mill effluent and press mud application (7.63 CFU (x106/g). While fungi and actinomycetes populations are higher in 75% paper mill effluent and farm yard manure application which were 5.64 CFU (x104/g) and 5.62 CFU (x104/g) respectively. The highest number of nodules was noticed in 100% paper mill effluent with press mud at 5 t/ha (45 numbers) followed by 75% paper mill effluent with press mud at 5 t/ha (42 numbers). From the study, it was concluded that the application of paper mill effluent with compost was found to be a promising source for soil fertility and root growth in groundnut.

Fertigation and Carboxymethyl Cellulose Applications Enhance Water-Use Efficiency, Improving Soil Available Nutrients and Maize Yield in Salt-Affected Soil

Conventional organic soil amendments and drip irrigation are insufficient for mitigating soil salinization. The development of a more potent soil amendment with higher water retention capability is critical. Carboxymethyl cellulose (CMC) has excellent water retention and adsorption properties and is suitable for soil water retention and amendment; however, its effects on water and salt distribution, soil nutrients, and maize yield have not been clearly investigated. We set up five treatments with flood irrigation (CK), drip irrigation (W), drip irrigation combined with 100 kg CMC ha−1 (WC1), drip irrigation combined with 200 kg CMC ha−1 (WC2), and drip irrigation combined with 300 kg CMC ha−1 (WC3). Our findings demonstrate that the application of CMC in conjunction with drip irrigation led to a significant surge in soil water content within the 0–40 cm layer, ranging from 3.73% to 16.46%, while simultaneously inducing a reduction in salt content of 4.08% to 16.61%. Consequently, this resulted in a desalination rate spanning from 10.32% to 12.93%. The salt was gradually washed down and formed a desalination area with the drip emitter as the center, and the salt distribution characteristics shifted from a surface accumulation type to a bottom deposition type. The drip irrigation and CMC application also increased the content of available nutrients, reduced surface evaporation, underground water loss, and maize evapotranspiration, and improved water-use efficiency, thus increasing the aboveground biomass and grain yield. In summary, CMC had a significant effect on water retention, desalination, and yield increases. It can serve as a novel soil amendment for salt-affected soil.

Long-term conservation tillage results in a more balanced soil microbiological activity and higher nutrient supply capacity

Soil health depletion due to intensive tillage operations is a global issue in the agricultural sector. Conservation tillage (CT) which involves non-inversion tillage and leaving ∼30% of the soil surface covered with crop residues, is a strategy designed to enhance soil health. However, no comprehensive study to investigate the long-term effect of CT on soil biological activity and the soil nutrient supply has yet been widely carried out. Biological and chemical soil properties were assessed at depths 0–5, 10–15, and 20–25 cm depths after 18 years of CT and conventional tillage practice (PT). Various stages in the vegetative growth of maize were investigated in 2021 in Hungary. The findings indicated that tillage intensity, soil depth, and growth stages all significantly influenced soil enzyme activities and the concentration of soil nutrients. Less soil disturbance resulted in a significantly larger concentration of soil carbon parameters (total organic carbon and labile carbon) in CT plots, where the activity of β-glucosidase and dehydrogenase (DHA) in the upper soil layer increased significantly (0.7–2.6 and 2.6–4.7 times, respectively) compared to PT. The high amount of organic matter and the greater resistance to erosion observed in CT also contributed to the higher concentration of available nutrients (NH4, NO3, Ca, K) and total P in the surface soil layer. Phosphatase activity was highest in the mid-stage of vegetative growth and was positively correlated to the total P concentration. The alterations in soil water content were clearly negatively correlated with the change in DHA and phosphatase activity. Overall, due to the more balanced environmental conditions, the decomposition of organic substances was more balanced and slower in CT than in PT. This implied that the mobilization of nutrients in the soil was more balanced as well, and that the nutrients were released gradually. The enhancement of the soil nutrient-supplying capacity achieved by means of long-term conservation tillage provides a promising strategy for sustainable nutrient management.

Arbuscular Mycorrhizal Fungi Promote the Degradation of the Fore-Rotating Crop (Brassica napus L.) Straw, Improve the Growth of and Reduce the Cadmium and Lead Content in the Subsequent Maize

Arbuscular mycorrhizal fungi (AMF) are widely present in heavy metal-polluted soils, but their effects on straw degradation and plant growth of rotated crops are poorly understood. In this study, a pot experiment was used to simulate the return of fore-rotating crop (Brassica napus L.) straw to farmland with a subsequent planting of maize in a lead–zinc mining area on the Yunnan Plateau, Southwest China, which included four treatments: control (CK), addition of rape straw (SR), inoculation of AMF (AMF), and both AMF inoculation and straw addition (AMF + SR). The effects of AMF on the degradation and nutrient release of the fore-rotating rape straw and the growth, mineral nutrition and the cadmium (Cd) and lead (Pb) contents of the subsequent maize were investigated. Compared with the CK treatment, AMF significantly promoted the degradation of rape straw and the release of mineral nutrients (nitrogen, phosphorus and potassium) as well as the Cd and Pb, increased the content of available nutrients in soil, and improved the mineral nutrient contents in the maize. AMF + SR significantly increased the maize height and biomass by 32–35% and decreased the available Cd and Pb contents in soil and the Cd and Pb contents in the maize by 20–30% and 18–25%, respectively. Moreover, the available Cd and Pb contents in the soil presented significant positive correlations with their contents in the maize but negative correlations with the height and biomass of the maize. Thus, AMF played an important regulatory role in the nutrient cycling and heavy metal accumulation of the crop rotation.

Biodegradation of organic compounds in the coal gangue by Bacillus sp. into humic acid.

Coal gangue (CG), one of the world's largest industrial solid wastes produced during coal mining, is extremely difficult to be used owing to its combined contents of clay minerals and organic macromolecules. This study explored a novel process of degrading the harmful organic compounds in the CG into humic acid using a biological method characterized by scanning electron microscope-energy dispersive spectrometer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), and elemental analyzer. The results reveal that adding selected Bacillus sp. to the CG for 40 days can increase the humic acid content by ~ 17 times, reaching 17338.17mg/kg, which is also the best level for promoting plant growth. FTIR and XPS spectra show that the organic compounds in the CG transforms primarily from C=C to C=O, COOH, and O-H groups, indicating that the organic compounds are gradually oxidized and activated, improving the humic acid concentration of soil. In addition, Bacillus sp. decreases pH and benzo[a]pyrene contents, and increases the content of available nutrients. After microbial degradation, coal gangue can be turned into ecological restoration materials.

Trifolium repens and biochar addition affecting soil nutrients and bacteria community.

Biochar has wide application prospects as a good soil conditioner, leguminous plants can fix nitrogen and improve soil available nutrients. However, it is not clear how adding biochar when planting leguminous plants affects soil bacterial community and soil available nutrients. This study investigates the effects of biochar addition on the content of ammonia nitrogen, Olsen-P, and available potassium in northeastern farmland soils under the plantation of Trifolium repens and then compared with the application of organic fertilizer. A 90-day incubation experiment was conducted to compare the changes in the structure and relative abundance of soil microflora under varied biochar additions. It was found that the addition of biochar could affect the structure of the microflora and the available nutrients in the soil. When compared with soil planted with T. repens without the addition of biochar, with the application of 3% biochar increased the content of ammonia nitrogen, Olsen-P, and available potassium in the soil by 31.71%, 21.40%, and 11.51%, respectively. High throughput sequencing revealed that the relative abundance of functional bacteria such as azotobacter, rhizobacteria, and phosphorus solubilizing bacteria in the soil increased with the addition of biochar. Furthermore, the effect was more obvious with the addition of organic fertilizers. The addition of biochar improved the microbial community structure and increased the relative abundance of functional bacteria and the content of available nutrients in the soil. This is expected to reduce the application of chemical fertilizers, thereby protecting the environment and conserving natural resources.

Changes in rhizospheric microbiome structure and soil metabolic function in response to continuous cucumber cultivation.

With the increasing reliance on intensive arable agriculture, analysis of the problems associated with continuous cropping has become a global research focus. Here, high-throughput sequencing and nontargeted metabolomics were used to evaluate the responses of soil microbial community structure and soil metabolic function to continuous cucumber cultivation (from 1 to 18 years of continuous cultivation) in greenhouses. Continuous cucumber cropping resulted in increased soil nutrient concentrations, but decreased concentrations of available nutrients. The abundance of several bacterial genera associated with nutrient cycling, such as Bacillus and Sphingomonas, was reduced by continuous cucumber cultivation. The abundance of several beneficial fungal genera, including pathogen antagonists (e.g. Chaetomium, Mortierella, Aspergillus, and Penicillium), were found to gradually decrease in response to the increased duration of continuous cropping. 3-amino-2-naphthoic acid and L-valine increased initially and then decreased as the cropping continued, which were related to fatty acid metabolism and amino acid biosynthesis. We also confirmed a close association between microbial community structure and soil metabolites. This study linked the changes in microbial community structure and metabolites in the rhizosphere soil and provided new insights into soil-microbial interactions in continuous cucumber culture systems.

Biochar-compost amendment enhanced sorghum growth and yield by improving soil physicochemical properties and shifting soil bacterial community in a coastal soil

Soil salinization, an important type of soil degradation, has become a problem restricting crop production and food quality. The remediation technologies by using compost and biochar were considered sustainable and environment friendly, but the sole application of compost or biochar hardly gets the satisfactory remediation effects. Until now, information about the effects of cocomposted biochar on soils is limited, especially in the coastal soil. This study investigated the impact and potential underlying mechanism of corn straw biochar (BC), seaweed compost (SC), and cocomposted BC and SC (BCSC) on the growth and yield of sorghum (Sorghum bicolor (L.) Moench) in the coastal soil of China in a pot experiment. BC and BCSC treatments increased the dry biomass and yield of the sorghum by 44.0–52.4% and 132.9–192.3%, respectively. Similarly, the root morphologies of sorghum, including surface area and average diameter, were also increased with BC and BCSC addition. Meanwhile, BCSC treatment showed a better performance than what the others did. The enhanced growth and yield of sorghum primarily resulted from the improvement of soil properties (WHC, SOM, and EC) and nutrient availability (Olsen-P and AK content). In addition, the increased diversity and shifted composition of soil bacteria with BC and BCSC addition might also account for the increased growth and yield of sorghum. Furthermore, the enhanced relative abundances of beneficial bacteria Vicinamibacteraceae (39.0%) and Sphingomonadaceae (41.5%) in the rhizosphere soil were positively correlated with the content of available nutrients (NH4+, Olsen-P, and available K) in the coastal soil, which might reveal the mechanism of enhancing growth under the established collaborative interactions of them. Our study provides the potential of using biochar-compost to ameliorate the degradation of coastal soils and improve crop yield.

Contribution of zooplankton nutrient recycling and effects on phytoplankton size structure in a hypereutrophic reservoir

AbstractConsumer nutrient recycling influences aquatic ecosystem functioning by altering the movement and transformation of nutrients. In hypereutrophic reservoirs, zooplankton nutrient recycling has been considered negligible due to high concentrations of available nutrients. A comparative analysis ( Moody and Wilkinson, 2019) found that zooplankton communities in hypereutrophic lakes are dominated by nitrogen (N)-rich species, which the authors hypothesized would increase phosphorus (P) availability through excretion. However, zooplankton nutrient recycling likely varies over the course of a growing season due to changes in biomass, community composition and grazing pressure on phytoplankton. We quantified zooplankton, phytoplankton and nutrient concentration dynamics during the summer of 2019 in a temperate, hypereutrophic reservoir. We found that the estimated contribution of zooplankton excretion to the dissolved nutrient pool on a given day was equivalent to a substantial proportion (21–39%) of the dissolved inorganic P standing stock in early summer when P concentrations were low and limiting phytoplankton growth. Further, we found evidence that zooplankton affected phytoplankton size distributions through selective grazing of smaller phytoplankton cells likely affecting nutrient uptake and storage by phytoplankton. Overall, our results demonstrate zooplankton excretion in hypereutrophic reservoirs likely helped drive springtime phytoplankton dynamics through nutrient recycling while grazing influenced phytoplankton size distributions.

Potassium Behavior with Clay Minerals Composition under Soil Ecosystem: it's Adequacy for Maize Plants

Purpose: The target area for the study is one of the agricultural areas of importance in Egypt. It is a suitable area for studying the origin and distribution patterns of clay minerals. Therefore, the focal aims of this study were: (1) to examine the clay minerals' origins in semi-arid regions of Egypt. (2) The behavioral pattern of K in clay minerals in ecological changes, (3) the reflection of K-behavior in soil on the maize plant's nutrient content under soil systems.&#x0D; Methodology: Evaluation of water samples were: Evaluate the pH and EC, soluble ions, sodium adsorption ratio (SAR), soluble sodium percentage (SSP), sodium to calcium activity ratio (SCAR), residual sodium bicarbonate (RSBC), and residual sodium carbonate (RSC). Also, Evaluation of soil samples were: Evaluate the particle size distribution, OM content, soil pH, Gypsum, CaCO3 content, cation exchange capacity (CEC), exchangeable sodium percentage (ESP), EC, soluble ions, Soil available K, exchangeable K, and total K. Separation of the clay fraction: preparation of soil samples for mineralogical analysis. Qualitative clay mineralogical analysis: X- ray diffactograms were obtained for some selected clay samples using Philips equipment pw (1140/90). Evaluation of plant samples were: Evaluate the N, P, and K concentrations. Statistical analysis: SPSS (v. 20) was used to determine the descriptive statistics and correlation analysis.&#x0D; Findings: Achieving study aims, a series of methodological steps were implemented to study soil and water properties, and their reflection on maize plants. The irrigation water results analysis showed no problems. The soil properties were also distinguished by the results: common features of this type of soil are a depth of greater than 120 cm, a slightly well-drained clay texture, and poor OM content. The CaCO3 content increases with depth. The available N, P, K were (slight to moderate, very low, and good) respectively. The EC values range from non-saline to moderate saline. As indicated, the X-ray diffraction patterns of the clay fractures are separated from those features. It appears from the analysis that the mineral composition of the clay fracture at both areas is dominated by montmorillonite, kaolinite, and then hydrated mica. Based on the studied soil characteristics, there was a reflection on the maize plant grown, which showed the following: A strong positive correlation between the soluble K content and K in maize plants at the age of 30 days. The multiple correlations were significantly positive between the N and P content available to the grain of maize plants. The results exposed a negative correlation between the available K and K content of maize plants at 45 days of age. Also, there was a significant negative correlation between the exchangeable K and K content in maize plants at 60 days of age.&#x0D; Contribution to theory, practice and policy: The results presented the significant relationships between the evaluation of the physical and chemical properties of the soil, the content of available nutrients, as well as the type of soil minerals, and their reflections and contributions on the elements contained in the different parts of the maize plants (stems and grains), according to the state of the maize plants age.

Autofluorescence Is a Common Trait in Different Oceanic Fungi.

Natural autofluorescence is a widespread phenomenon observed in different types of tissues and organisms. Depending on the origin of the autofluorescence, its intensity can provide insights on the physiological state of an organism. Fungal autofluorescence has been reported in terrestrial and human-derived fungal samples. Yet, despite the recently reported ubiquitous presence and importance of marine fungi in the ocean, the autofluorescence of pelagic fungi has never been examined. Here, we investigated the existence and intensity of autofluorescence in five different pelagic fungal isolates. Preliminary experiments of fungal autofluorescence at different growth stages and nutrient conditions were conducted, reflecting contrasting physiological states of the fungi. In addition, we analysed the effect of natural autofluorescence on co-staining with DAPI. We found that all the marine pelagic fungi that were studied exhibited autofluorescence. The intensity of fungal autofluorescence changed depending on the species and the excitation wavelength used. Furthermore, fungal autofluorescence varied depending on the growth stage and on the concentration of available nutrients. Collectively, our results indicate that marine fungi can be auto-fluorescent, although its intensity depends on the species and growth condition. Hence, oceanic fungal autofluorescence should be considered in future studies when fungal samples are stained with fluorescent probes (i.e., fluorescence in situ hybridization) since this could lead to misinterpretation of results.

Contrasting biodiversity and food web structure of three temporary freshwater habitats in a tropical biodiversity hotspot

Abstract In many biomes, a variety of different small freshwater habitats, such as pools and phytotelmata can occur together in the same habitat matrix. However, both the biodiversity and the functioning of these ecosystems remain poorly known. Three freshwater habitat types in a tropical West African biodiversity hotspot were studied. The study demonstrated that animal communities in water‐filled tree holes, temporary ponds and granite rock pools were strongly differentiated with exclusive faunas despite their spatial proximity and similar disturbance in the form of seasonal drought. In particular, granite rock pools stood out with a high gamma diversity. Rock pools were also functionally different from the other two habitat types. The three habitats had contrasting predator assemblages, a differential reliance on primary production and different concentrations of available nutrients. The work illustrates that the biodiversity and functions of small temporary freshwater habitats can be strongly differentiated. This shows the unique and potentially complementary roles that these habitats can fulfil in mediating fluxes of energy and nutrients and preserving aquatic biodiversity in landscapes. Temporary aquatic habitats are typically overlooked in conservation policy and local management plans despite being threatened by habitat transformation. In addition, livestock can threaten savanna ponds, wood exploitation can threaten tree holes, and mining and sediment disruption can threaten rock pools. Hence, better knowledge about the ecological functioning of these ecosystems is vital to the implementation of effective conservation strategies.