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The rapid rise of cyanotoxins production poses a serious threat to global freshwater ecosystems and has become an important issue of global public health. In Africa, a continent facing serious environmental problems, including poisoning by cyanotoxins, knowledge of the presence and distribution of these toxins remains limited. The primary objective of our review is to assess the occurrence and distribution of cyanotoxins, particularly microcystins (MCs), in African freshwater ecosystems. We aim to analyze the limited but existing literature on this subject, focusing specifically on studies published between 2001 and 2023. Recognizing the scarcity of research on this topic in Africa, we strive to elucidate the emerging patterns of toxin variants and their correlation with environmental variables, such as water temperature and nutrient concentrations. Our investigation reveals MCs as the predominant cyanobacterial secondary metabolites detected across the majority of African freshwater environments where cyanotoxins have been documented. Furthermore, their concentrations have exceeded the World Health Organization's (WHO) provisional guideline for lifetime human exposure through drinking water, which is set at 1 µg L−1, as indicated by data in Table 1. Highly significant positive relationships were found between toxin-producing cyanobacteria and environmental factors, in particular water temperature and nutrient concentrations. Given the associated exposure risks in Africa, we recommend frequent monitoring of water quality, the development of guidelines based on international best practice, toxicity tests, and epidemiological investigations to understand the health risks and impacts of cyanotoxin exposure. These measures are essential to both protect the well-being of humans and to ensure the sustainability of African aquatic ecosystems. [ABSTRACT FROM AUTHOR]

The aim of the study was to analyse precipitation, subsurface runoff and concentrations of nutrients in water (NH4 +- -N, NO3 --N and PO4 3- ions). The study was conducted at the lysimetric station in Jaworki (Małe Pieniny, Nowy Targ district, Malopolska province, 600 m a.m.s.l.). Measurements were carried out during vegetation periods, from April to September. The paper consists of an analysis of data in two periods - 2001-2018 and 2019-2022. Data in the historical years (2001-2018) showed that water quality as well as its quantitative variability was low, mainly until 2015. The year 2018 indicated slow changes in this regard. Analysis of the years 2019-2022 indicated that the outflow was almost identical. The years 2019 and 2022 were characterized by significantly higher leachate concentrations. Ammonium ion contents were similar. Analysis of nitrate ions in leachate showed an increasing trend over the years. Phosphates, on the other hand, showed a similar trend to nitrate ions. The study showed which types of land use have the greatest impact on both subsurface runoff volume and leachate water quality. In mountainous conditions, the type of use, as well as the climate and soil, have an extremely significant impact on the volume and quality of runoff, which affect the quality of groundwater and surface water. [ABSTRACT FROM AUTHOR]

The pressure to plant seedlings in unprepared instead of prepared soil in forest regeneration is increasing, although seedlings' growth in unprepared soil is poorer. One way to improve seedlings' growth could be to add arginine phosphate to the planting hole at the time of planting. In field studies, abiotic and biotic damage normally disturbs studies which seek to determine growth effects, especially in unprepared soil. The study's aims were (i) to clarify whether it was possible to investigate the differences between varying soil layer structures mimicking site preparation methods and seedling treatments in simulated planting places in partly controlled conditions; and (ii) to investigate the effects of arginine phosphate (arGrow® Granulat) on the growth, especially root growth, of Norway spruce (Picea abies (L.) H. Karst.) and Scots pine (Pinus sylvestris L.) container seedlings in those simulated planting places. Seedlings of both tree species were planted in 40 l pots sunk partly into the soil in a sandy field. Before planting, pots were filled with soil layers mimicking layers in soil without any site preparation treatment and in spot mounds. After one growing season, the differences in growth parameters between treatments were small in Norway spruce seedlings, and no significant benefits of arginine phosphate were observed. The soil in the spruce pots was fine-textured and contained a thick organic layer. More studies in more common forest soil types suitable for Norway spruce seedlings are needed to be sure about the growth responses. In Scots pine seedlings, adding arginine phosphate granules to the planting holes improved the growth of seedlings at least in the first summer after planting in soil layers mimicking no mechanical site preparation situation, and the growth improvement may even have compensated the mounding effects. In conclusion, mimicking site preparation methods in large pots was a promising method by which the differences between site preparations methods as well as effects of seedling treatments, in our case arginine phosphate, on the growth of conifer seedlings, can be tested. [ABSTRACT FROM AUTHOR]

Quercus rehderiana Hand.-Mazz. belongs to Quercus sect. Heteroallenes' of the Fagaceae family. It is widely distributed in forests with rocky and non-rocky desertification in Guizhou Province of Southwest China. However, our knowledge of the adaptation strategies of Quercus in forests with rocky desertification is surprisingly lacking. In this study, 16 leaf traits (morphological, anatomical, and chemical) of Quercus rehderiana were investigated in 15 individuals in five 20 × 20 m quadrants of forests with rocky and non-rocky desertification. The aim was to analyze their strategies of adaptation to arid and poor-soil environments in forests with rocky desertification. The results showed that Quercus rehderiana leaves in forests with rocky desertification had a greater leaf thickness, specific leaf area, abaxial epidermis thickness, and sponge mesophyll thickness but a lower leaf area than in forests with non-rocky desertification. Quercus rehderiana leaves in forests with rocky desertification had higher calcium and magnesium concentrations and a higher N:P ratio but lower potassium and phosphorus concentrations than in forests with non-rocky desertification. The results of principal component analysis showed that forests with rocky desertification tended to show resource-conserving strategies with thicker leaf tissue and a lower nutrient concentration, while forests with non-rocky desertification tended to show resource acquisition strategies with a greater leaf area and potassium concentration. In resource-poor environments, species that adopt conservative resource strategies are more likely to survive; therefore, we forecasted that more conservative, slow-growing Quercus rehderiana will be more stable over time. [ABSTRACT FROM AUTHOR]

The contribution of two basal energy sources - detrital organic matter and primary producers - as part of aquatic food webs varies typically along river continua. A host of barriers to river flow increase the water residence time and sediment and nutrient retention in reservoirs worldwide, and potentially alter the balance between detritus-based and algae-based energy pathways in the downstream food webs. We explored this issue on the Sélune River (Normandy, France), a small coastal stream that drains an agricultural catchment with high sediment runoff. Seasonal measurements of the following parameters were compared upstream and downstream of the reservoirs of two large dams (16 m and 36 m high): sediment fluxes, nutrient and chlorophyll a concentrations, algal communities in the epilithic biofilm (taxonomic composition, biomass and growth), and benthic invertebrate communities (abundance and trophic guild structure). As anticipated, annual sediment fluxes were much lower downstream of the reservoirs, where significant decreases in water turbidity, phosphate and silicate concentrations were recorded. A higher chlorophyll a concentration in water and a higher contribution of pelagic algae taxa to the photosynthetic biofilm suggested drifting and deposition of reservoir-borne phytoplankton downriver. Photosynthetic biofilm growth was higher downstream of the reservoirs in spring and fall, and so was the abundance of herbivores in the invertebrate community, notably scrapers and algae eaters. Energy pathways within riverine food webs were traced using stable isotope analyses of carbon (C) and nitrogen in the tissues of aquatic consumers (invertebrates and fish). Mixing models revealed a discontinuity in the origin of the C entering the food webs along the river continuum, confirming a greater contribution of algal C to aquatic consumers downstream of the reservoirs. These results illustrate mechanisms whereby large reservoirs can modulate C flow in food webs along a small coastal river with high sediment loads, and make it possible to anticipate the effects of dam removal on the future river ecosystem. [ABSTRACT FROM AUTHOR]

Background: Cachichín (Oecopetalum mexicanum Greenm. & C.H. Thomps: Metteniusaceae) is an arboreal species native to the Misantla mountain range, Veracruz, Mexico, whose fruit contains an edible seed with potential nutraceutical properties. Basic biochemical analyses have been performed, though the effects of thermal treatments on the concentration of vital molecules, the seed structure and the histochemistry have yet to be elicited. Herewith we determined the effect of different thermal treatments on the concentrations of total sugars; glucose and fructose; proteins; and amino acids; as well as the impact of such treatments on the anatomy and histochemistry of seeds. Methods: Biochemical, anatomical, and histochemical characterizations of the cachichín seed were carried out in raw form (T1) and under three thermal treatments: boiled (T2), commercial toasting (T3), and controlled toasting (T4). The biochemical variables evaluated were total and reducing sugars, total proteins, and total amino acids. Observations of the seed structure were performed by scanning electron microscopy (SEM), while histochemical staining was carried out to identify starch, lipids, tannins, polysaccharides and proteins under compound light microscopy. Results: Concentration of total sugars was reduced in boiled (T2) and commercial toasting (T3) seeds as compared to raw (T1) and controlled toasting (T4) seeds; boiled seeds (T3) displayed the lowest concentration of total sugars. An increase in the concentrations of glucose and fructose was observed in T4. As compared to T1, all other treatments did not change protein concentrations in the seed; the only significant difference observed was between T2 and T3, with commercial toasting displaying the highest mean for this variable. Amino acid concentrations decreased in T3 and T4 compared to T1, while in T2 the concentration of these molecules increased. The anatomic analysis of (T1) revealed a well-organized structure, compared to applied thermal treatments, where degradation of anatomical structures was observed. In general, the thermal treatments tested modified the concentrations and distribution of starch, lipids, tannins, polysaccharides and proteins as compared to raw seeds. The raw cachichín seed has a well-defined anatomical and cellular compartmental organization, while the application of the thermal treatments caused a loss of its structural organization and degradation of vital biomolecules. Conclusion: The cachichín seed can be considered a good source of proteins and lipids. Thermal treatments can improve its organoleptic properties, though they negatively impact its nutritional value and anatomical structure. Among thermal treatments tested, the controlled toasting can maintain or even improve some nutraceutical properties with a few structural and biochemical modifications. [ABSTRACT FROM AUTHOR]

Tea (Camelia sinensis) is one of the most consumed beverages in the world. Research on the nutritional characteristics of tea, particularly lowland tea plantations, is limited in Malaysia. Thus, we aimed to investigate the nutritional characteristics (N, P, K, Ca, Mg, Al, Fe) and antioxidant activity of seven clonal teas (663, 2026, 2024, AT53, TV9, 1294, and 1428) planted at a tropical lowland tea plantation, Bukit Cheeding, Selangor, and their association with the soil edaphic factor. All foliar nutrient concentrations except for Ca and antioxidant activities varied significantly (p<0.05) among tea clones. Clone AT53 had the highest foliar K (1.84 ± 0.7 mg g-1 ), Mg (0.80 ± 0.3 mg g-1 ), Fe (12.97 ± 1.4 mg g-1 ), and Al (16.61± 1.4 mg g-1 ). Clone 663 had the highest P (13.76 ± 1.06 mg g-1 ), and clone 2026 had the highest N (4.39 ± 0.2%). Clone 1248 had the highest antioxidant activity at 50.66 ± 3.2 µg mL-1. Tea foliar N and P concentrations were significantly associated with the N and P of the soil. Besides, several soil nutrients were significantly intercorrelated with foliar nutrient concentrations. Results from this study may benefit growers in selecting better quality clones and managing lowland tea plantation at Bukit Cheeding, Selangor, Malaysia. Good farm management may improve the productivity and sustainability of tea plantations. [ABSTRACT FROM AUTHOR]

The contribution of two basal energy sources – detrital organic matter and primary producers – as part of aquatic food webs varies typically along river continua. A host of barriers to river flow increase the water residence time and sediment and nutrient retention in reservoirs worldwide, and potentially alter the balance between detritus-based and algae-based energy pathways in the downstream food webs. We explored this issue on the Sélune River (Normandy, France), a small coastal stream that drains an agricultural catchment with high sediment runoff. Seasonal measurements of the following parameters were compared upstream and downstream of the reservoirs of two large dams (16 m and 36 m high): sediment fluxes, nutrient and chlorophyll a concentrations, algal communities in the epilithic biofilm (taxonomic composition, biomass and growth), and benthic invertebrate communities (abundance and trophic guild structure). As anticipated, annual sediment fluxes were much lower downstream of the reservoirs, where significant decreases in water turbidity, phosphate and silicate concentrations were recorded. A higher chlorophyll a concentration in water and a higher contribution of pelagic algae taxa to the photosynthetic biofilm suggested drifting and deposition of reservoir-borne phytoplankton downriver. Photosynthetic biofilm growth was higher downstream of the reservoirs in spring and fall, and so was the abundance of herbivores in the invertebrate community, notably scrapers and algae eaters. Energy pathways within riverine food webs were traced using stable isotope analyses of carbon (C) and nitrogen in the tissues of aquatic consumers (invertebrates and fish). Mixing models revealed a discontinuity in the origin of the C entering the food webs along the river continuum, confirming a greater contribution of algal C to aquatic consumers downstream of the reservoirs. These results illustrate mechanisms whereby large reservoirs can modulate C flow in food webs along a small coastal river with high sediment loads, and make it possible to anticipate the effects of dam removal on the future river ecosystem.

Background Cachichín (Oecopetalum mexicanum Greenm. & C.H. Thomps: Metteniusaceae) is an arboreal species native to the Misantla mountain range, Veracruz, Mexico, whose fruit contains an edible seed with potential nutraceutical properties. Basic biochemical analyses have been performed, though the effects of thermal treatments on the concentration of vital molecules, the seed structure and the histochemistry have yet to be elicited. Herewith we determined the effect of different thermal treatments on the concentrations of total sugars; glucose and fructose; proteins; and amino acids; as well as the impact of such treatments on the anatomy and histochemistry of seeds. Methods Biochemical, anatomical, and histochemical characterizations of the cachichín seed were carried out in raw form (T1) and under three thermal treatments: boiled (T2), commercial toasting (T3), and controlled toasting (T4). The biochemical variables evaluated were total and reducing sugars, total proteins, and total amino acids. Observations of the seed structure were performed by scanning electron microscopy (SEM), while histochemical staining was carried out to identify starch, lipids, tannins, polysaccharides and proteins under compound light microscopy. Results Concentration of total sugars was reduced in boiled (T2) and commercial toasting (T3) seeds as compared to raw (T1) and controlled toasting (T4) seeds; boiled seeds (T3) displayed the lowest concentration of total sugars. An increase in the concentrations of glucose and fructose was observed in T4. As compared to T1, all other treatments did not change protein concentrations in the seed; the only significant difference observed was between T2 and T3, with commercial toasting displaying the highest mean for this variable. Amino acid concentrations decreased in T3 and T4 compared to T1, while in T2 the concentration of these molecules increased. The anatomic analysis of (T1) revealed a well-organized structure, compared to applied thermal treatments, where degradation of anatomical structures was observed. In general, the thermal treatments tested modified the concentrations and distribution of starch, lipids, tannins, polysaccharides and proteins as compared to raw seeds. The raw cachichín seed has a well-defined anatomical and cellular compartmental organization, while the application of the thermal treatments caused a loss of its structural organization and degradation of vital biomolecules. Conclusion The cachichín seed can be considered a good source of proteins and lipids. Thermal treatments can improve its organoleptic properties, though they negatively impact its nutritional value and anatomical structure. Among thermal treatments tested, the controlled toasting can maintain or even improve some nutraceutical properties with a few structural and biochemical modifications.

Changhu Lake, a large, shallow, eutrophic lake in central China, experienced an extremely low water level event from November 2015 to January 2016 followed by an extremely high water level event in July 2016. In this study, we examined the effects of two extreme water levels on the nutrient dynamics of Changhu Lake over five years. The nutrient parameters in Changhu Lake showed significant interannual variations, and the nutrient concentrations at the sites in the western part of Changhu Lake were 2–41% higher than those at the outlet of the lake. In late 2015, the effects of low water levels led to a 17–74% increase in nutrient concentrations. After July 2016, however, a high water level event occurred, leading to a 34–48% decrease in nutrient concentrations. These changes in nutrient parameters were strongly related to water level fluctuations (p

Decreased water levels due to climate change cause many negative effects on lake ecosystems. The aim of this study was to (a) assess the effect of the reduction of water levels on nutrient availability in the sediment in the littoral zone; (b) evaluate the effect of changes in water level on biomass productivity and nutrient concentrations in the aboveground biomass of four emergent species: Phragmites australis (Cav.) Trin. ex Steud., Typha angustifolia L., Carex acutiformis L., Glyceria maxima (C. Hartm.) Holmb; and (c) assess the efficiency of the littoral zone in the reduction of nutrient pollution. The study hypothesis was that water level reduction has a positive effect on the plant biomass of high productive species. The study was carried out in the littoral zone of Tomickie Lake, situated in the western part of Poland. This lake is located in the protected area—the buffer zone of Wielkopolska National Park, and at the international level—Natura 2000. Six transects, perpendicular to the shoreline, were selected at two subzones—permanently and seasonally flooded. Analyses of nutrient concentrations in sediments and plant species were performed. The results show the higher productivity of reeds in the zone where water occurs seasonally at the site through the year, which reached 1193 g dry weight/m2. The decline of the water level may lead to the increased growth of highly productive species as emergent vegetation with a broad ecological scale in terms of nutrient concentrations and changes of water depth, i.e., Phragmites australis (Cav.) Trin. ex Steud. Species that prefer growth in the deeper part of the lake will be characterized by lower productivity, despite the high availability of nutrients. Changes in the availability of nutrients may cause the intensification of lake overgrowth by very productive species, which may affect biodiversity, which is particularly high in protected areas. [ABSTRACT FROM AUTHOR]

Intensive agricultural management practices (i.e., the burning of pruning residues, the absence of organic amendments) lead to a reduction in organic matter and nutrients in the soil resulting in agroecosystem vulnerability. Implementing a cover crop would provide soil organic matter while increasing nutrition levels in the soil. A mixture of cover crop trial in sandy loam soils under Mediterranean climatic conditions was conducted in a rainfed olive grove in Western Crete. In this study, the dry biomass, macro- and micronutrition, and carbon status of the seeded cover crops (legume and grass) were compared to natural plants in an olive grove. Seeded cover crops were conducted in two sustainable management systems (cover crops solely, and a combination of compost, pruning residues, and cover crops); natural plants were in a conventional system involving soil tillage. In combination with conservation tillage practices, the addition of carbon inputs may improve soil fertility. Results indicate that the dry biomass production and C content of cover crops under sustainable management systems was significantly higher than that of the control. The higher dry biomass production and C content found in cover crops compared to the natural vegetation indicates not only that this type of management provides enhanced carbon storage, but can also potentially lead to a future increase in soil organic matter through decomposition. Higher dry biomass is important in the context of carbon sequestration, and cover crops facilitated carbon storage in this study. In addition, this study suggests that sustainable agricultural management practices would provide significant benefits in terms of nutrient retention and CO2 fixation, thus improving ecosystems in Mediterranean countries.

Restoration of the bog known as the Leegmoor was accompanied by multiple challenging factors such as lack of a white peat layer, strong water table fluctuations and inhibited lateral water movement. The project started in 1983 and was supported by scientific monitoring. Now, almost 40 years later, the monitoring has been repeated to gauge success. As part of this initiative we investigated nutrient dynamics by monitoring soil and water chemistry (NH4+, NO3-, PO43-, pH, Nt, Pt) and soil water content in 2019–2020 and comparing our results with data from the 1980s and 1990s. Soil water content had increased significantly. Soil NO3--N content had decreased significantly and was mostly below the detection limit, while pH and NH4+-N had not changed. Pore water PO43--P concentrations remained above those observed in near-natural bogs, while nutrients (except NH4+-N) in the surface water had decreased to levels observed in near-natural bogs. Most of the observed nutrients had decreased, some to near-natural levels, although the Leegmoor continued to receive an atmospheric supply of nutrients from adjacent agricultural areas. Our results indicate translocation of nutrients into the vegetation, which has developed substantially, but this process can be expected to end at some point.

The iron ore tailings released into the Rio Doce basin after the Fundão dam collapse (Brazil), suppressed a large extent of local vegetation. The use of native species and appropriate fertilization techniques, with less economic and environmental impact, must be considered in the process for the restoration of affected areas by the tailings. For this purpose, six native tree species, pioneer (Anadenanthera colubrina, Bixa orellana, and Peltophorum dubium) and secondary (Cedrela fissilis, Handroanthus impetiginosus, and Handroanthus serratifolius), were selected. We used different conditions of fertilization: (1) inorganic fertilization, (2) inoculation with arbuscular mycorrhizal fungi and plant growth-promoting rhizobacteria, (3) combined treatment (fertilizer + inoculum), to evaluate leaf nutrient concentrations, photosynthetic capacity [chlorophyll index, maximum quantum efficiency of photosystem II (Fv/Fm) and gas exchange variables], and oxidative metabolism (H2O2, MDA, and antioxidant enzymes). Inoculation resulted in higher concentrations of foliar nitrogen, especially in pioneer species. In all treatments, the secondary species exhibited iron values considered phytotoxic, but showed reduced photosynthetic capacity only when inoculated. The highest concentrations of MDA were observed in inoculated plants of both successional groups. The antioxidant system proved to be effective in preventing oxidative damage for most of the species. These results showed that the use of inoculum can be considered an ecological alternative to inorganic additives in the area affected by iron ore tailings. Despite presenting different photosynthetic and antioxidant strategies, the evaluated species demonstrated potential for use in tailings revegetation projects. [ABSTRACT FROM AUTHOR]

Changhu Lake, a large, shallow, eutrophic lake in central China, experienced an extremely low water level event from November 2015 to January 2016 followed by an extremely high water level event in July 2016. In this study, we examined the effects of two extreme water levels on the nutrient dynamics of Changhu Lake over five years. The nutrient parameters in Changhu Lake showed significant interannual variations, and the nutrient concentrations at the sites in the western part of Changhu Lake were 2–41% higher than those at the outlet of the lake. In late 2015, the effects of low water levels led to a 17–74% increase in nutrient concentrations. After July 2016, however, a high water level event occurred, leading to a 34–48% decrease in nutrient concentrations. These changes in nutrient parameters were strongly related to water level fluctuations (p < 0.05). As extreme water levels are likely to become more frequent during the twenty-first century, this work may provide some insights into the conservation and management of lake ecosystems in the face of climate change and human activity. [ABSTRACT FROM AUTHOR]

Conservation agriculture with use of crop rotations and residue management provides many benefits to the soil and environment, which vary depending on climatic and soil conditions, crops between of the rotation, and the amount of incorporated residue. The present study evaluated the effect of two medium-term of canola (Brassica napus L.)-wheat (Triticum aestivum L.) and bean (Phaseolus vulgaris L.)-wheat rotations with four residue incorporation rates of preceding crop (0, 50, 100, and 200%) on wheat grain yield and nutrient concentrations; Nitrogen (N), Phosphorous (P), Potassium (K), Calcium (Ca), Magnesium (Mg) and Sulfur (S) at the end of the fourth season in a volcanic soil in south-central Chile. Grain yield varied between 5.77 and 5.96 Mg ha−1 and was not affected by the preceding crop. The residue incorporation rates had no effect on the evaluated parameters. The preceding crop affected grain K and Mg concentration, which increased after bean. The Ca concentration in the residue was positively affected by the canola crop. Total macronutrient extraction in the wheat crop was 444.1 kg ha−1. The ranking of total macronutrient extraction in the wheat crop was N > K > P > Ca > S > Mg with means of 198–221, 26.1–30.6, 133–163, 20.8–27.1, 13.4–16.5, and 14.9–16.5 kg ha−1, respectively. [ABSTRACT FROM AUTHOR]

Intensive agricultural management practices (i.e., the burning of pruning residues, the absence of organic amendments) lead to a reduction in organic matter and nutrients in the soil resulting in agroecosystem vulnerability. Implementing a cover crop would provide soil organic matter while increasing nutrition levels in the soil. A mixture of cover crop trial in sandy loam soils under Mediterranean climatic conditions was conducted in a rainfed olive grove inWestern Crete. In this study, the dry biomass, macro- and micronutrition, and carbon status of the seeded cover crops (legume and grass) were compared to natural plants in an olive grove. Seeded cover crops were conducted in two sustainable management systems (cover crops solely, and a combination of compost, pruning residues, and cover crops); natural plants were in a conventional system involving soil tillage. In combination with conservation tillage practices, the addition of carbon inputs may improve soil fertility. Results indicate that the dry biomass production and C content of cover crops under sustainable management systems was significantly higher than that of the control. The higher dry biomass production and C content found in cover crops compared to the natural vegetation indicates not only that this type of management provides enhanced carbon storage, but can also potentially lead to a future increase in soil organic matter through decomposition. Higher dry biomass is important in the context of carbon sequestration, and cover crops facilitated carbon storage in this study. In addition, this study suggests that sustainable agricultural management practices would provide significant benefits in terms of nutrient retention and CO2 fixation, thus improving ecosystems in Mediterranean countries. [ABSTRACT FROM AUTHOR]

Mariculture provides an increasing seafood supply to a growing population. It also brings unintended consequences for the environment, resources, and sustainable development. In an attempt to evaluate the impacts of intensive mariculture of lobster in cages, the water quality and sediment quality in three South-Central regions of Vietnam, Xuan Dai Bay, Van Phong Bay, and Cam Ranh Bay, were monitored from April 2019 to May 2020. In each bay, two stations in the farming areas were compared to a non-farming reference station. The result showed no significant differences in the water quality parameters among the stations within each bay and between the bays. However, sediment quality noticeably differed between sites within each bay and between the bays. The accumulation of the observed parameters of sediment in farming areas was higher than in non-farming areas. In the Cam Ranh Bay, the concentration of organic carbon, total nitrogen, and total phosphorus in the sediment in farming areas was approximately 1.4 times higher compared to non-farming areas. Similar results were found in Van Phong Bay and Xuan Dai Bay with different magnitudes. Additionally, the difference in the sulfide concentration in the sediment of Van Phong Bay was notable for its better environmental quality than the other two. The findings indicated that mariculture wastes would accumulate in the sediment, and decompose over time, causing sediment degradation, which may affect the benthic biota in coastal waters. [ABSTRACT FROM AUTHOR]

ABSTRACT The ruderal babassu palm (Attalea speciosa) is expanding on large areas of degraded Amazon landscapes. Decomposition of leaves and roots is in the center of plant:soil interactions. We evaluated decomposition and nutrient concentrations of leaves and fine roots of babassu in comparison with two exotic reference species, Acacia mangium (slow degradability) and Leucaena leucocephala (fast degradability), in a 138-day litterbag assay carried out in secondary forest stands of different age and babassu abundance. We chose 4-mm over 2-mm mesh litterbags based on a pilot study. Babassu leaves degraded slower than leaves of A. mangium and L. leucocephala, and also had lower nitrogen, phosphorus and calcium concentrations in all stages of decomposition. By contrast, potassium concentrations in babassu leaves were higher than in both reference species at 0 and 50 days. Roots of all three species decomposed slower than leaves. Compared to the leaves, both biomass loss and nutrient concentrations differed less between babassu and reference-species roots, except for lower nitrogen concentration in babassu roots. Leaf-litter decomposition of all three species was significantly faster in old than in young secondary forest, suggesting an acceleration of decomposition along succession. Babassu leaves decomposed faster in old babassu-dominated than non-dominated secondary forest, pointing to the existence of specialized decomposer communities in babassu-dominated stands.

In mesotidal estuaries, the spatial and temporal variation of physicochemical and biological parameters, and thus water quality, is strongly influenced by tidal dynamics. Hence, to improve monitoring and management strategies, it is imperative to understand how tidal conditions affect water quality parameters and the overall water quality assessments. Multiple indexes and water quality indicators have been used to address water quality issues, monitoring and reporting, mainly in the scope of the Water Framework Directive (WFD). In this work, the tidal effect on nutrients, dissolved oxygen, suspended solids (SPM), Secchi depth, chlorophyll a and phytoplankton composition in a temperate mesotidal estuary was assessed. Moreover, the effect of tidal conditions on the water quality indicators and classification systems was also evaluated. This study was conducted at two stations (Barreiro and Alcântara) located in the Tagus Estuary (Lisbon, Portugal), presenting different anthropogenic pressures. Nutrient concentrations were the variables which yielded the highest differences in response to the tidal conditions, especially at Alcântara, where the influence of a nearby outfall was evident. Therefore, Alcântara also presented stronger classification variability in response to the tidal effect, especially in classifications with less salinity classes. Results indicate that low neap tide is the best tidal condition to assess the worst-case scenario due to the low dilution factor. However, it is important to highlight that all tidal conditions should be sampled to understand the overall condition of water bodies. The classification using mean as a metric (TRIX) was more susceptible to the presence of high nutrient concentrations in general, while the 90th percentile responded better to the presence of several high values in an area with lower nutrient concentrations.

A pot experiment was conducted to determine the influence of commercial nanoparticles (ZnO-NPs) at different doses for use as nanofertilizer on nutrient uptake and its distribution in cherry tomato (Solanum lycopersicum L var. cerasiforme) plants in an acidic (soil pH 5.5) and calcareous soil (soil pH 8.5) from the Mediterranean area. We determined crop yield; macro- (N, P, K, Mg, S and Ca) and micro-nutrient (B, Cu, Fe, Mn, Na and Zn) concentrations in the different parts of the crop (root, stem, leaves and tomato fruits) and the extent of nutrient translocation to the aerial part of the plant. The concentrations of macronutrients N, P, K and Mg in tomato fruits grown in both soils can be considered adequate in terms of nutritional requirements. However, the Ca concentration in tomato fruits grown in the calcareous soil did not reach the required concentration to be considered sufficient. This effect was related to the characteristics of this calcareous soil. Although different concentrations of ZnO-NPs did not affect Fe and Na concentrations in tomato fruit, B concentration in tomato fruits increased with the application of ZnO-NPs. In addition, Cu concentration decreased with the application of ZnO-NPs compared to treatments without any Zn application (Nil-ZnO NP) in the calcareous soil. Manganese concentrations decreased with ZnO-NPs application in both soils. The effect of the application of ZnO-NPs depends on soil characteristics. Zinc applied as a nanofertilizer in the form of ZnO-NPs can be used to increase the crop yield and to obtain an adequate Zn biofortification in cherry tomato crop. The Zn concentrations in tomato fruits reached ranges of 4.5–4.8 mg Zn kg−1 in the acidic soil and 2.5–3,5 mg Zn kg−1 in the calcareous soil. Nutrient concentrations in these fruits following biofortification are adequate for human consumption.

Restoration of the bog known as the Leegmoor was accompanied by multiple challenging factors such as lack of a white peat layer, strong water table fluctuations and inhibited lateral water movement. The project started in 1983 and was supported by scientific monitoring. Now, almost 40 years later, the monitoring has been repeated to gauge success. As part of this initiative we investigated nutrient dynamics by monitoring soil and water chemistry (NH4+, NO³-, PO43-, pH, Nt, Pt) and soil water content in 2019-2020 and comparing our results with data from the 1980s and 1990s. Soil water content had increased significantly. Soil NO3--N content had decreased significantly and was mostly below the detection limit, while pH and NH4+-N had not changed. Pore water PO43--P concentrations remained above those observed in near-natural bogs, while nutrients (except NH4+-N) in the surface water had decreased to levels observed in near-natural bogs. Most of the observed nutrients had decreased, some to near-natural levels, although the Leegmoor continued to receive an atmospheric supply of nutrients from adjacent agricultural areas. Our results indicate translocation of nutrients into the vegetation, which has developed substantially, but this process can be expected to end at some point. [ABSTRACT FROM AUTHOR]

Foliar nutrient concentrations, contents, and ratios are important indicators for the nutritional status of trees. They depend on the availability of nutrients and the uptake capacities of the trees, which are controlled by forest structure, soil and climate condition. Consequently, accounting for climate conditions can aid the interpretation of foliar chemistry measurements.We applied a moving-window approach to identify the effects of atmospheric temperature and precipitation on tree nutrition at different time intervals based on data collected by institutions of the German Federal States within the ICP Forests Level II network. We studied the main nutrients N, P, K, Ca, and Mg as well as foliar mass for the main temperate tree species (European beech, temperate oaks, Norway spruce, Scots pine).Results show that foliar traits of all main tree species are affected by either current and/or lagged climate condition. Nutrient concentrations are generally less sensitive to climate condition than foliar mass and nutrient contents. Nutrient contents show the same response direction to climate condition as foliar mass, while nutrient concentrations mostly show an opposite response, potentially indicating the existence of dilution effects. Only Ca content in spruce shows weak effects of climate as changes in foliar mass are entirely counterbalanced by opposing changes in Ca concentrations.For spruce, pine, and oak significant climate effects on nutrient ratios were found. In general, N:P, N:K, and P:K are less sensitive to climate variations than ratios including Mg or Ca. In beech, all nutrient concentrations show a similar response to climate condition. Nutrient ratios in beech are thus relatively robust against climate condition compared to concentrations and contents.Our results highlight that intervals of less than three month provide a good indication of the climatic impact on tree nutrition. Longer periods, or means over several years, are less suitable as indicators. Defined periods show, however, a significant role of climate beside soil factors and species on foliar nutrition and should therefore be considered for the interpretation of tree nutrition.

The highest increase in grain Zn concentration was observed with foliar Zn application followed by ZnCU and least with soil Zn application. Among various Zn fertilization options, 3% ZnCU and soil application of Zn (5 kg/ha) was found most promising for improvement in growth attributes, grain and straw yields and Zn, N, P, K and S concentrations in rice grain. Therefore, Zn application through 3% ZnCU to rice is a recommendable option for improving rice productivity and its nutritional status in NEH region of India.

PGPR is widely used to improve the capacity of soil nutrient retention, which is closely related to soil microbial activity and enzyme activity. Biochar amendment can alter soil physicochemical properties, such as soil pH and the capacity of water holding. We conducted a study in Guangxi, China, in January 2018 to determine the responses of soil nutrient concentrations and enzyme activities to PGPR and biochar applications in a eucalyptus plantation. Bacillus megatherian strain Du07 was isolated from eucalyptus rhizosphere soil and was confirmed to be a PGPR by partial 16S rDNA sequencing. Biochar applied in our study was made from wheat straw and was used at three application levels (0 t.hm−2, 20.0 t hm−2, 40 t.hm−2). The following treatments were evaluated: (1) no PGPR and no biochar applied (M0B0), (2) 5 × 1010 cfu/mL PGPR (MB0), (3) 20.0 t.hm−2 biochar (B20), (4) 5 × 1010 cfu/mL PGPR plus 20.0 t.hm−2 biochar (MB20), (5) 5 × 1010 cfu/mL PGPR plus 40.0 t.hm−2 biochar (MB40). In general, separate application of PGPR and biochar may increase soil urease activity, total nitrogen (TN), and total potassium (TK) concentrations, and co-application of PGPR and biochar may increase soil sucrase activity, electrical conductivity (EC), and TK concentration, indicating that the manner of biochar and PGPR application had a significant influence on soil physicochemical properties and enzyme activities except for TK concentration. Redundancy analysis (RDA) showed that soil NO3−-N, NH4+-N, TK, TP, and SWC were more closely related to soil enzyme activities than other soil physicochemical properties under our experimental conditions. [ABSTRACT FROM AUTHOR]

With the pressure on coral reefs increasing, effective mapping of tropical coastal areas affected by anthropogenic nutrient input is essential in conserving existing reefs and to also restore reefs that may already be degraded. However, it is often difficult to detect the source of nutrients entering the reef ecosystem due to the rapid dilution and mixing of nutrients through currents, wave activity and other general mixing events. It is therefore recommended for water quality assessments that biological assays (bioassays) and chemical data are collected as well as biological and habitat data. A bioassay involves the use of a biological organism to test for the relative strength of a substance within the natural environment. This study attempts to quantify the amount, and find the source, of nutrient inputs into the marine environment on a developing tourist island in Thailand. Chemical data in the form of nutrient concentrations are used as an indication of the amount of nutrients present; while δ15N values in algae tissue are used to indicate the source of nutrients and whether or not they are of anthropogenic origin. A more detailed review of the current literature on tracing anthropogenic nutrient inputs using these methods is given below. Also reviewed is the current knowledge of the effects of nutrients on a coral reef ecosystem along with the various mechanisms involved.

Previous studies suggested that strong positive correlations between microbial taxa destabilized the microbial communities, because high synchrony between taxa caused different taxa responded in tandem to the changes of environmental conditions. In this study, we used nutrient concentrations (nitrogen and phosphorus) as indicators for anthropogenic activities, and explored the effects of anthropogenic activities on the stability of bacterial communities in a subtropical river, Xiyuan River. We also used co-occurrence networks to indicate the synchrony between bacterial taxa. The nutrient concentrations were higher in the midstream and downstream areas than in the upstream area of Xiyuan River. As a result, the average proportion and correlation coefficient of positive correlations were higher in the midstream and downstream networks than in the upstream networks. This indicates that frequent anthropogenic activities increased the synchrony between taxa in the midstream and downstream communities, and therefore destabilized the bacterial communities. To further explore the mechanisms, we found that the changes of community stabilities associated with the changes of bacterial functions. Anthropogenic activity tolerant bacteria (e.g., nutrient removal, aromatic degradation and pathogen bacteria) and their linked bacterial taxa formed large and strong positive modules in the midstream and downstream networks, and thus destabilized the communities. Based on the perspective of microbial correlations, our results provide a new insight in the mechanisms of how anthropogenic activities alter riverine microbial communities. [ABSTRACT FROM AUTHOR]

The effects of an intercropping system combined with organic fertilizer application on the yield quality of medicinal plants and the involved mechanisms have not been well elucidated. To evaluate the effects of different fertilizers (vermicompost and chemical fertilizers) on the dragonhead essential oil (DEO) productivity (dragonhead = Dracocephalum moldavica L.) (D) in sole cropping and intercropping with common bean (Phaseolus vulgaris L.) (CB), a 3‐year field experiment was carried out using a factorial based on randomized complete block design. We found that the highest common bean seed yield and dry matter productivity of dragonhead were obtained from sole cropping fertilized with vermicompost. Regarding the major DEO constituents, the highest content of geranyl acetate (42.2%), geranial (23.4%), and geraniol (17.81%) were recorded using the cropping ratio of 2D:1CB following the use of vermicompost. Soil micro‐biochemical parameters (basic microbial respiration, substrate‐induced respiration, microbial biomass carbon, alkaline and acid phosphatase, and urease) in the intercropping systems were found to be higher than those of the corresponding sole croppings. The highest soil microbial activity was observed in the intercropping ratios of 2D:1CB and 1D:2CB following the use of vermicompost. Furthermore, the highest land equivalent ratios (LER = 1.28) were achieved in the intercropping ratio 2D:1CB after vermicompost application. Thus, this combination of stimulated soil microbial activity and functionality, which in turn accelerated nutrient mobilization and availability, enhanced plant performance. Therefore, we can conclude that intercropping dragonhead with common bean at the ratio of 2D:1CB coupled with vermicompost application can be introduced as an alternative and sustainable strategy to reduce the use of chemical fertilizers. [ABSTRACT FROM AUTHOR]

The application of carbon-rich substrates to agricultural soils is discussed as a strategy to improve soil properties and fertility, which can affect plant physiological traits and enhance agricultural crop yield. The aim of this study was to evaluate if shungite, carbon-rich sedimentary-volcanic rock, may improve plant ecophysiological traits under sufficient water supply as well as soil water deficit. A pot culture experiment was conducted with onion (Allium cepa L.) seedlings, using four shungite concentrations (0, 5, 10 and 20 g kg−1) in an Umbric Podzols and two water regimes: well-watered and drying-wetting cycles. Soil water deficit decreased root nutrient content, depressed seedlings growth, net CO2 assimilation rate (An), stomatal conductance (gs) and the respiration rates in both darkness (Rd) and the light (Rl), but increased water use efficiency (WUE) at leaf level. Shungite application decreased the leaf necrosis under both water regimes and increased total leaf length of DW seedlings. Compared with the well-watered conditions, under drying-wetting cycle shungite stimulated the increase of the An rate and WUE at low measurement temperature. No significant effect of shungite was found for Rd, Rl, Rl/Rd, Rd/Ag (Ag = An + Rl) and Rl/Ag regardless soil water regimes. Shungite application was not so successful to eliminate the negative effects of soil water deficit on growth and physiological processes of A. cepa. The observed positive effects of shungite on the physiological traits of onion seedlings were more likely associated with the increase in the content of nutrients than with the improvement in soil water properties. [ABSTRACT FROM AUTHOR]

Residue incorporation in agriculture associated with crop rotation, benefits the environment, soil fertility, and crop production. However, the benefits of conservation agriculture practices in soil fertility and crop yield increases come up after several years. To study durum wheat (Triticum turgidum L.) crop production under conservation agriculture with incorporation of residues a biannual rotation experiment was conducted in a volcanic soil in south-central of Chile.The experiment consisted was comprised of two crops, canola (Brassica napus L.) and bean (Phaseolus vulgaris L.), and four levels of residue incorporation (0%, 50%, 100%, and 200% of generated residue). Results indicated that grain yield, grain P, and residue K concentrations were higher when the previous crop was bean. Sedimentation values (SDS test), yellowness values (b), grain N concentration, grain and residue Ca concentrations, were higher when the previous crop was canola. The different leves of applied residue for the previous crop only presented effect on sedimentation values and yellowness values. Even though to obtain consistent results about the effect of different residue levels on a crop rotation experiments a larger number of crops cycles is required, the present work showed relevant results in a short time crop rotation. Bean pre-crop increases durum wheat grain yield respect to canola crop in short-time rotations. Canola pre-cop increases sedimentation and yellowness value in durum wheat grain. [ABSTRACT FROM AUTHOR]

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Abstract The present study reported the effect of natural and anthropic environmental variables on the fish assemblages in the pampean streams, in the coastal strip along the Río de la Plata, Buenos Aires province, Argentina. Five streams were sampled at 12 sites surrounded by land devoted to different uses. A correspondence analysis sorted the streams into two groups: a less impacted group formed by sites surrounded by livestock- raising pastures and a more impacted one passing through urban sites and including a stream adjacent to a modest rural urbanization with a dairy in the stream’s basin. The nutrient concentrations were significantly higher in the more impacted group; with species richness, diversity, abundance, and biomass being significantly lower. A canonical-correspondence analysis linked the more impacted sites to high concentrations of soluble reactive phosphorus and impoverished fish assemblages, composed of species tolerant to environmental pollution. On the other hand, sites with higher oxygen concentrations and pH were related to richer assemblages pointing to good environmental conditions at the sites surrounded by livestock-raising pastures. The downstream sites on the less impacted streams contained fish assemblages in which the juvenile stages of species corresponding to the Río de la Plata were dominant.

Seagrass conservation and management requires scientific understanding of spatial and temporal variability, information that is currently limited for the Eastern Tropical Pacific (ETP). Here, we analysed seagrass presence based on previous reports, herbarium collections and stakeholder knowledge, combined with field characterization in Golfo Dulce, southern Pacific coast of Costa Rica. Seagrasses were found at multiple locations along a narrow border close to shore and in up to 6 m depth within Golfo Dulce, dating back to 1969. Two seagrass species were found, Halophila baillonii and Halodule beaudettei. Seagrass biomass values for Golfo Dulce (12.0 ± 8.5 g DW m−2) were lower and water nutrient concentrations were higher than previously reported in the gulf. Shoot density (1513 ± 767 shoots m−2) was similar to previous reports. Stable isotope values in seagrass were −11.3 ± 1.0‰ δ13C and 1.2 ± 0.9‰ δ15N; while those in sediments were −26.1 ± 1.3 and 2.5 ± 0.9‰. In Golfo Dulce, isotopic values of both seagrass species do not overlap with other known primary producers. Management strategies should aim to minimize known seagrass stressors, protect potential seagrass habitat, and take into account the dynamic life strategies of the two seagrass species found. [ABSTRACT FROM AUTHOR]

Bioremediation techniques, particularly landfarming and vapour extraction, have been used successfully and have been reported to be cost effective. In spite of the success of bioremediation, it is observed that degradation of pollutants in soil is generally slow and needs to be accelerated. [ABSTRACT FROM AUTHOR]

Salt accumulation gradually changes the cycling of carbon (C), nitrogen (N), and phosphorus (P) and may even transform sinks into sources in arid wetlands. However, it's not clear how hydrochemical characteristics affect the wetland's source or sink function or how they affect C, N, and P cycling in arid regions. To clarify these relationships, we conducted field measurement in arid northern China. We simulated the variations of hydrochemical characteristics and the storage and stoichiometry of C, N, and P using the process‐based DeNitrification‐DeComposition (DNDC) and Hydrus‐1D models. The meteorological and hydrological processes had obvious characteristics of seasonal and interannual changes. The measured evapotranspiration averaged 660.23 and 587.94 mm year−1 in the saltmarsh and riparian wetlands, respectively. The soil showed a clear trend with higher SO42−, Na+, Ca2+, and Cl− fractions in comparison with lower Mg2+, K+, and HCO3− fractions, with the major ion and nutrient concentrations gradually decreasing with increasing depth in the soil. The major ion types had characteristics of Na+‐Ca2+‐SO42−‐Cl− in the saltmarsh wetland and riparian wetland. The storage of total C, N, and P were 372.72 ± 66.52 t C/hm2, 10.92 ± 2.59 t N/hm2, and 17.55 ± 1.54 t P/hm2 in the saltmarsh wetland versus 119.72 ± 27.88 t C/hm2, 4.38 ± 1.24 t N/hm2, and 13.17 ± 1.46 t P/hm2 in the riparian wetland. Therefore, wetland salinization in our study led to increased soil C, N, and P contents and storage and thereby enhanced the sink function of the wetlands. Key Points: We simulated the variations of hydrochemical characteristics and the storage and stoichiometry of C, N, and PThe model coupled the Hydrus‐1D and DNDC models to solve a drawback of hydrochemical simulationWe identified the mechanisms by which hydrochemical characteristics determine the transport and cycling of soil nutrient [ABSTRACT FROM AUTHOR]

Shifts in species distributions are among the observed consequences of climate change, forcing species to follow suitable environmental conditions. Using species distribution models (SDMs), we aimed at predicting trends in habitat shifts of two seaweed species of commercial interest in the Subantarctic Patagonian region in response to ongoing environmental changes across temperate South America and worldwide. We gathered occurrence data from direct, on-site visual, and taxonomic identification (2009–2018) from global databases of species occurrence and from the scientific literature. We built the SDMs selecting putative predictors of biological relevance to Lessonia flavicans and Gigartina skottsbergii. We calibrated the SDMs using MaxEnt and GLMs for model evaluation, splitting our occurrence datasets into two parts: for model training and for model testing. The models were projected to future climate change scenarios (Representative Concentration Pathway: RCP 2.6 and RCP 8.5) to examine trends in shifting habitat suitability for each species. Maximum sea surface temperature was the main predictor variable, followed by minimum nitrate concentration, explaining both species' distributional shift across Subantarctic shorelines by the year 2050. Projection of the SDM for each species under altered environmental conditions to 30–40 years into the future resulted in a south poleward shift with a reduction in habitat range for both species. Such responses would threaten their persistence, local marine species richness, biodiversity, ecological function, and thereby, the commercial and ecosystem services provided by L. flavicans and G. skottsbergii in Subantarctic South America. [ABSTRACT FROM AUTHOR]

The study aimed to assess the performance, carcass traits, chemical and amino acids (AA) composition of breast and thigh meat organically reared Barred Plymouth Rock (BPR) chickens fed different nutrient concentrations. A total of 240 one-day-old BPR mixed-sex chicks (average weight 35.57±0.17 g) were allocated in a complete randomized design into 3 dietary treatments with 8 replicates of 10 chicks each, and used in an 84-d feeding trial according to organic meat technology (Regulations 834/2007 and 848/2018). Dietary treatments consisted of a basal isocaloric and isonitrogenous organic diet as a control (T0), isocaloric and low-crude protein (CP) level organic diet (T1; 1% CP lower) and isonitrogenous and low-metabolizable energy (ME) level organic diet (T2; 220 kcal/kg ME lower). Results showed that dietary treatments did not influence the overall weight gain of BPR chicks, but feed conversion ratio was poorer in experimental (T1 and T2) diets than in control. There were no effects of dietary treatments on carcass traits and digestive organs. Proximate composition (dry matter, fat, protein, ash) and energy value of meat were not altered bytreatments, except the protein content of thigh muscle significantly decreased in T1 compared to the other treatments. Certain individual AA, which included phenylalanine in breast muscle, as well as lysine and phenylalanine in the thigh muscle, decreased by fed T1 diet, leading to a significant decrease in both breast and thigh muscles of total AA (TAA) and essential AA (EAA) in T1 than the other treatments. The non-essential AA (NEAA) and the ratios of EAA/TAA or EAA/NEAA did not differ among treatments. Our results show that irrespective of dietary treatments or muscle type, the meat of BPR chicks has a balanced AA profile with more than 40% EAA/TAA ratio and more than 60% EAA/NEAA ratio. In conclusion, these findings indicate that fed low-energy diet (2770 kcal/kg ME and 21.4% CP in starter-grower phase, respectively 2880 kcal/kg ME and 18.6% CP in finisher phase)in BPR chicks represents an alternative with no adverse effect on productive performance, carcass traits, and meat protein quality. [ABSTRACT FROM AUTHOR]

Anthropogenic eutrophication remains a critical global issue, significantly impacting surface water quality. Numerous regions have implemented beneficial management practices to combat agricultural nonpoint pollution, often evaluating efficacy at the field scale, but not downstream. In this study, we conducted an extensive, 11-year (2010–2020), all-season, weekly monitoring program in a small, shallow, hypereutrophic lake and main tributary located in a cold climate, northern temperate zone, within a predominantly agricultural-forested mesoscale watershed. The monitoring took place before and after the implementation of field-scale agricultural nutrient mitigation measures in the catchment, allowing assessment of changes over time in the downstream tributary and lake. We analyzed long-term trends and temporal change points for nitrogen and phosphorus concentrations, aquatic trophic status, and nutrient stoichiometric ratios. The results revealed significant reductions in nitrogen and phosphorus concentrations, improved lake trophic status from hypereutrophic to eutrophic, and an increase in total nitrogen : total phosphorus ratios following the implementation of field-scale agricultural nutrient mitigation measures. Notably, both the lake and its main tributary exhibited significant temporal change points for these parameters. Our findings offer evidence of a relatively rapid, positive effect of the implementation of field-scale agricultural nutrient mitigation measures contributing to subsequent improvements in downstream water quality. [Display omitted] • A hypereutrophic lake and tributary were monitored weekly, year-round, for 11 years. • Agricultural nutrient mitigation measures were implemented in the watershed. • Nutrient mitigation measures led to reduced downstream nitrogen and phosphorus. • Lake trophic status improved from hypereutrophic to eutrophic. • Nutrient concentration and stoichiometry temporal change points were identified. [ABSTRACT FROM AUTHOR]

Brazilian Cerrado soils are commonly deficient in boron (B) and zinc (Zn). It is still debated whether B and Zn interaction has a synergistic or antagonistic effect on the absorption thereof. Thus, we conducted this study to evaluate the effect of boron rates (0, 1, 2, 3, and 4 kg ha?1, as boric acid), with or without zinc fertilization (2 kg ha?1 Zn, as zinc sulfate), on corn nutritional status and grain yield. We also assessed the residual effect of such fertilization on the fall corn crop grown on an Oxisol in a no-tillage system. A synergistic effect between B and Zn was observed on corn nutritional status when applied to the soil at rates of up to 2 kg ha?1, with higher soil contents resulting from the interaction between these micronutrients. Zinc fertilization and increasing boron rates had no significant influence on corn grain yield in both spring/summer and fall crops, grown on a boron-deficient, clayey soil of Cerrado biome.

Minimum soil disturbance and increased crop residue retention practices are promising options to enhance soil organic matter, nutrient concentration and crop yield. However, the potentials of the practices in improving soil properties, increasing crop yield and in ensuring economic return have not been tested in the monsoon rice (Oryza sativa L.)-lentil (Lens culinaris L.)/wheat (Triticum aestivum L.)-jute (Corchorus culinaris L.) cropping systems on seasonally flooded lowlands of the Eastern Gangetic Plain of South Asia. A field trial for consecutive three years was conducted in the Gangetic Plains of Bangladesh to evaluate the effects of zero tillage (ZT), strip-tillage (ST), bed planting (BP) and conventional tillage (CT) with two residue retention levels (RL—a low level similar to current farmers’ practice and RH—increased retention) on soil properties, yield and economic return. Between rice and jute crops, lentil was grown for the 1st and 2nd years and wheat for the 3rd year during the dry winter season. The ST and BP performed better than the CT and ZT in terms of yield of rice and lentil, whereas ST and ZT performed better than other practices in the case of jute. Higher residue retention (RH) increased crop yield for all the years. The highest rice equivalent yield (sum of 3 crop yields, expressed as rice yield) and the greatest benefit-cost ratio (BCR) were recorded with ST and RH. The increased yield in the ST was associated with reduced soil bulk density (BD), while ST with RH increased soil water (SW) and decreased penetration resistance (PR) of soil. Compared to CT, minimum soil disturbance of ZT and ST increased soil organic matter (SOM) stock by 24% and 23%, respectively; total nitrogen (TN) by 23.5% and 18.4%, respectively; extractable sulphur (S) by 21% and 18%, respectively; whereas Zinc (Zn) concentrations increased by 53% and 47%, respectively, in the upper 0–5 cm soil depth. Accumulation of extractable P, S and Zn in the 0–5 cm depth of soil followed the sequence as ZT > ST > BP > CT practice. The higher amount of residue retention significantly increased SOM, TN and extractable P, K, S and Zn concentrations at 0–5 cm and 5–10 cm soil depths. The 3-year study suggests that ST with RH is a potential crop management approach for the seasonally flooded rice-lentil/wheat-jute cropping systems to enhance soil nutrients status, crop yield and farm economy.

Silicon (Si) is considered a beneficial element for plants due to the far-reaching benefits it confers, including enhanced growth, yield, and crop quality, as well as stress resistance. In this study, we evaluated the effect of Si during germination and initial growth (0.0, 0.5, 1.0, or 1.5 mM Si) and during vegetative growth (0, 1, 2, or 3 mM Si) in rice (Oryza sativa) cv. Morelos A-98. Si did not affect germination but stimulated seedling height, root length, number of roots, as well as fresh and dry biomass weight of shoots and roots during initial growth. During vegetative growth, the application of 3 mM Si significantly increased the chlorophyll a/chlorophyll b ratio, but no major changes were observed either in growth or in concentrations of most nutrients, with the exception of Ca (which increased with 3 mM Si), and B and Zn (which decreased in the presence of Si). In conclusion, applying Si had positive effects during the initial stage of growth, increasing seedling height, root length, root number, and fresh and dry biomass weight. Under our experimental conditions, Si did not affect germination and vegetative growth, but increased Ca concentrations and decreased B and Zn concentrations. [ABSTRACT FROM AUTHOR]

The Nachchaduwa sub-catchment (598.74 km2) of the Malwathu Oya basin is seasonally stressed in the dry periods and its downstream parts undergo intermittent floods during monsoon seasons while the fate and behaviour of excess nitrogen (N) and phosphorus (P) added to the waterways due to agricultural fertilisers used in the upstream areas remain unresolved. This study incorporated the Water and Energy Transfer Processes (WEP) model to assess the present status of the catchment concerning water resources and pollutant transport. Results showed that the catchment response to the rainfall is highly regulated due to reservoir storage effect (ungauged basin with regulated flows). The amounts of N and P in fertilisers applied in this catchment exceeded the actual plant requirement. In both wet [Maha cultivation season (October to March)] and dry [Yala cultivation season (April to September)] seasons, the differences between the upstream and downstream values of measured water quality parameters (N and P components - total, dissolved and particulate) in waterways were not statistically significant. On average, the wet season had about 5~7 times the dry season value of the total suspended solids (TSS) in the streams, and in both seasons, the modelled TSS, NO- 3 and PO3-4 were within the ranges of the previously published results. This study will be continued in the future to analyse possible hydrological and material transport related scenarios to identify best water resources management practices and to pragmatically cope with the excess fertiliser usage, an issue commonly found in most of the similar catchments. [ABSTRACT FROM AUTHOR]

To reduce losses and improve forage use efficiency in dairy farming systems, mass and nutrient flows during silage production have to be measured from the field to feed bunk. However, data on these losses at the farm scale are scarce. Thus, we examined dry‐matter (DM) losses and changes in nutrient concentrations (proximate constituents, nitrogen [N], phosphorus [P]) and energy values (net energy for lactation [NEL]) of silages on three experimental farms from ensiling to feed‐out. The investigated material included forages from permanent grassland and whole‐crop maize that were stored in 64 side‐walled bunker silos. To determine DM losses, the total‐in versus total‐out method was applied. Additionally, the changes in the nutrient concentrations were measured by comparing the concentrations before and after ensiling. Data analyses were carried out by using ANOVA, and the means across groups were compared via multiple contrast tests. On average, the farms had good silage production management. Average values showed a trend towards higher DM losses during the ensiling process with grass (9%) than maize (7%). The N and P concentrations of the silages remained mainly unchanged during the ensiling process, suggesting that the total losses of N and P were also low (<10%). Regarding the fibre fractions, ensiling resulted in a significant reduction in the concentration of amylase‐treated ash‐excluded neutral detergent fibre (aNDFom) for grass (11%) and maize (15%), while ash‐excluded acid detergent fibre (ADFom) was not affected by the ensiling process. These changes resulted in slightly improved energy values in the silages. [ABSTRACT FROM AUTHOR]

The determination of the trophic status of transitional ecosystems from the physico-chemical and biological point of view is one of the requirements of the European Water Framework Directive (WFD 2000/60/EC). In Italy, its determination is implemented by the Regional Agencies for Environmental Protection (ARPAs) that have activated multi-annual monitoring programs. However, as the availability of funds is increasingly scarce, the number of environmental parameters to detect environmental changes should be conveniently managed. The high number of environmental parameters, nutrient and macrophyte datasets available for the LTER-Italia site "Venice lagoon" can be an useful tool to analyze the trophic changes over recent years and to foresee environmental evolutions. Nutrient data on a spatial basis have been available since 1948, whereas macroalgal maps date back to 1980. The aim of this paper is to highlight the changes of the trophic status of the lagoon since the middle of the 20th century by considering the concentrations of nutrients in the surface sediments and in the water column, the variation of some physico-chemical parameters and the biomass of macroalgae and also to foresee the way it will possibly evolve. In fact, after many anthropogenic impacts that in the second half of the 20th century affected the lagoon, starting from the year 2010, the ecological status is progressively improving. Nutrients show a significant reduction both in the water column and in surface sediments, and the macrophytes are represented by species of higher ecological value while the opportunistic species such as the Ulvaceae are in strong regression. [ABSTRACT FROM AUTHOR]