Статті в журналах: "Nutrient cycles"

1

Coleman, David C., and E. R. Ingham. "Terrestrial nutrient cycles." Biogeochemistry 5, no. 1 (February 1988): 3–5. http://dx.doi.org/10.1007/bf02180315.

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2

Hendrickson, O. Q., and J. Richardson. "Nested forest nutrient cycles: implications for plantation management." Forestry Chronicle 69, no. 6 (December 1, 1993): 694–98. http://dx.doi.org/10.5558/tfc69694-6.

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Natural forests may be viewed as containing nested nutrient cycles: an "external" cycle mediated by atmospheric processes, a "soil" cycle of litter production and decay, and one or more "plant" cycles involving retranslocation and internal storage pools. The goal of plantation forest management should be to enhance all of these cycles. Stimulating the "external" cycle by adding fertilizer nutrients is likely to increase "soil" and "plant" cycling rates as well. A basic understanding of how these nested cycles are linked can improve the management of nutrients in forest plantations.

3

COMERFORD, N. "Forest Soils and Nutrient Cycles." Soil Science 146, no. 6 (December 1988): 467. http://dx.doi.org/10.1097/00010694-198812000-00009.

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4

Alam, Jamaluddin Fitrah, Tamiji Yamamoto, Tetsuya Umino, Shinya Nakahara, and Kiyonori Hiraoka. "Estimating Nitrogen and Phosphorus Cycles in a Timber Reef Deployment Area." Water 12, no. 9 (September 9, 2020): 2515. http://dx.doi.org/10.3390/w12092515.

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In an oligotrophic bay, Mitsu Bay, Japan, artificial timber reefs (ATRs) are deployed to increase fish production. In such man-made ecosystems, the biological activities of other organisms as well as the physical structures of ATRs could influence nutrient cycling. A pelagic–benthic coupling model expressing both phosphorus and nitrogen cycling was developed to investigate seasonal variation in the associated nutrients and their annual budget in the ATR areas and the entire bay system. The model consists of equations representing all the relevant physical and biological processes. The model reproduced the observed seasonal variations in dissolved inorganic P, ammonium, and nitrate concentrations that were low in spring and summer and high in autumn and winter. The internal regeneration rates of the nutrients were two times higher in the ATRs than in the bay area, so that fish production was predicted to be higher in the ATRs than in the bay area. Considering the inflows from the land and precipitation are quite low, nutrient regeneration is an important source of nutrients for the water in Mitsu Bay. ATR deployment could be an important local nutrient source in an oligotrophic bay, and could increase fish production.

5

Moore, C. M. "Microbial proteins and oceanic nutrient cycles." Science 345, no. 6201 (September 4, 2014): 1120–21. http://dx.doi.org/10.1126/science.1258133.

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6

Arrigo, Kevin R. "Marine microorganisms and global nutrient cycles." Nature 437, no. 7057 (September 14, 2004): 349–55. http://dx.doi.org/10.1038/nature04159.

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7

Vasconcelos Fernandes, Tânia, Rabin Shrestha, Yixing Sui, Gustavo Papini, Grietje Zeeman, Louise E. M. Vet, Rene H. Wijffels, and Packo Lamers. "Closing Domestic Nutrient Cycles Using Microalgae." Environmental Science & Technology 49, no. 20 (September 29, 2015): 12450–56. http://dx.doi.org/10.1021/acs.est.5b02858.

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8

Fasham, M. J. R. "Antarctic nutrient cycles and food webs." Estuarine, Coastal and Shelf Science 25, no. 4 (October 1987): 483. http://dx.doi.org/10.1016/0272-7714(87)90041-2.

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9

Pascual, Mercedes, and Hal Caswell. "From the Cell Cycle to Population Cycles in Phytoplankton-Nutrient Interactions." Ecology 78, no. 3 (April 1997): 897. http://dx.doi.org/10.2307/2266068.

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10

Pascual, Mercedes, and Hal Caswell. "FROM THE CELL CYCLE TO POPULATION CYCLES IN PHYTOPLANKTON–NUTRIENT INTERACTIONS." Ecology 78, no. 3 (April 1997): 897–912. http://dx.doi.org/10.1890/0012-9658(1997)078[0897:ftcctp]2.0.co;2.

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11

Welti, Ellen A. R., Karl A. Roeder, Kirsten M. de Beurs, Anthony Joern, and Michael Kaspari. "Nutrient dilution and climate cycles underlie declines in a dominant insect herbivore." Proceedings of the National Academy of Sciences 117, no. 13 (March 9, 2020): 7271–75. http://dx.doi.org/10.1073/pnas.1920012117.

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Evidence for global insect declines mounts, increasing our need to understand underlying mechanisms. We test the nutrient dilution (ND) hypothesis—the decreasing concentration of essential dietary minerals with increasing plant productivity—that particularly targets insect herbivores. Nutrient dilution can result from increased plant biomass due to climate or CO2 enrichment. Additionally, when considering long-term trends driven by climate, one must account for large-scale oscillations including El Niño Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), and Pacific Decadal Oscillation (PDO). We combine long-term datasets of grasshopper abundance, climate, plant biomass, and end-of-season foliar elemental content to examine potential drivers of abundance cycles and trends of this dominant herbivore. Annual grasshopper abundances in 16- and 22-y time series from a Kansas prairie revealed both 5-y cycles and declines of 2.1–2.7%/y. Climate cycle indices of spring ENSO, summer NAO, and winter or spring PDO accounted for 40–54% of the variation in grasshopper abundance, mediated by effects of weather and host plants. Consistent with ND, grass biomass doubled and foliar concentrations of N, P, K, and Na—nutrients which limit grasshopper abundance—declined over the same period. The decline in plant nutrients accounted for 25% of the variation in grasshopper abundance over two decades. Thus a warming, wetter, more CO2-enriched world will likely contribute to declines in insect herbivores by depleting nutrients from their already nutrient-poor diet. Unlike other potential drivers of insect declines—habitat loss, light and chemical pollution—ND may be widespread in remaining natural areas.

12

Ford, Benjamin A., Geraldine J. Sullivan, Lisa Moore, Deepa Varkey, Hannah Zhu, Martin Ostrowski, Bridget C. Mabbutt, Ian T. Paulsen, and Bhumika S. Shah. "Functional characterisation of substrate-binding proteins to address nutrient uptake in marine picocyanobacteria." Biochemical Society Transactions 49, no. 6 (December 9, 2021): 2465–81. http://dx.doi.org/10.1042/bst20200244.

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Marine cyanobacteria are key primary producers, contributing significantly to the microbial food web and biogeochemical cycles by releasing and importing many essential nutrients cycled through the environment. A subgroup of these, the picocyanobacteria (Synechococcus and Prochlorococcus), have colonised almost all marine ecosystems, covering a range of distinct light and temperature conditions, and nutrient profiles. The intra-clade diversities displayed by this monophyletic branch of cyanobacteria is indicative of their success across a broad range of environments. Part of this diversity is due to nutrient acquisition mechanisms, such as the use of high-affinity ATP-binding cassette (ABC) transporters to competitively acquire nutrients, particularly in oligotrophic (nutrient scarce) marine environments. The specificity of nutrient uptake in ABC transporters is primarily determined by the peripheral substrate-binding protein (SBP), a receptor protein that mediates ligand recognition and initiates translocation into the cell. The recent availability of large numbers of sequenced picocyanobacterial genomes indicates both Synechococcus and Prochlorococcus apportion >50% of their transport capacity to ABC transport systems. However, the low degree of sequence homology among the SBP family limits the reliability of functional assignments using sequence annotation and prediction tools. This review highlights the use of known SBP structural representatives for the uptake of key nutrient classes by cyanobacteria to compare with predicted SBP functionalities within sequenced marine picocyanobacteria genomes. This review shows the broad range of conserved biochemical functions of picocyanobacteria and the range of novel and hypothetical ABC transport systems that require further functional characterisation.

13

Wilhelm, Steven W., and Curtis A. Suttle. "Viruses and Nutrient Cycles in the Sea." BioScience 49, no. 10 (October 1999): 781–88. http://dx.doi.org/10.2307/1313569.

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14

Arrigo, Kevin R. "Erratum: Marine microorganisms and global nutrient cycles." Nature 438, no. 7064 (November 2005): 122. http://dx.doi.org/10.1038/nature04265.

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15

Adame, María Fernanda, Bernardino Virdis, and Catherine E. Lovelock. "Effect of geomorphological setting and rainfall on nutrient exchange in mangroves during tidal inundation." Marine and Freshwater Research 61, no. 10 (2010): 1197. http://dx.doi.org/10.1071/mf10013.

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One of the key ecosystem services provided by mangroves is their role in mediating nutrient exchange, thereby protecting coastal ecosystems from negative impacts of nutrient enrichment. In this study, we tested whether geomorphological setting and level of rainfall affect the intensity and direction of nutrient exchange. Our hypotheses were that tidal mangroves retain more nutrients than riverine mangroves and that nutrient retention is stronger during periods of high rainfall. Concentrations of soluble reactive phosphorus (SRP), nitrogen oxides (NOx–-N) and ammonium (NH4+) were measured from water entering and leaving the mangroves during tidal cycles. Our results show that nutrient concentrations were higher in the flood tide compared with the ebb tide by up to 28% for NOx–-N, 51% for SRP and 83% for NH4+, suggesting retention by the mangroves. Geomorphological setting determined nutrient exchange to some extent, with some riverine sites receiving more nutrients than tidal sites and thus, being more important in nutrient retention. Rainfall was important in determining nutrient exchange as it enhanced SRP and NH4+ retention. These results show that mangroves can improve water quality of creeks and rivers, and underscore the need for conservation of mangroves over a range of geomorphological settings.

16

Larsen, T. A., M. Maurer, K. M. Udert, and J. Lienert. "Nutrient cycles and resource management: implications for the choice of wastewater treatment technology." Water Science and Technology 56, no. 5 (September 1, 2007): 229–37. http://dx.doi.org/10.2166/wst.2007.576.

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We look at the most important issues of the global nitrogen and phosphorus cycle and conclude that the nutrients from human metabolism are of no importance for the global nitrogen cycle and of minor importance for the global phosphorus cycle. However, for water pollution control, N and P from the human metabolism are of extreme importance. Nitrogen is mainly an issue for coastal waters, whereas P is an issue for freshwater and coastal areas alike. It is by now generally recognised that coastal ecosystems are exceedingly important for human well-being and at the same time highly endangered. The recycling issue is of high importance in areas where nutrient application is low due to economic constraints. NoMix technology (urine source separation) holds a large promise to become an efficient mainstream technology. The largest short-term potential is found in densely populated areas in coastal areas without existing infrastructure and in areas with nutrient deficiency, especially in urban areas with a large nutrient potential. We believe, however, that these technologies will, with time, also become competitive in Europe.

17

Islam, Waqar, Arfa Tauqeer, Abdul Waheed, and Fanjiang Zeng. "MicroRNA Mediated Plant Responses to Nutrient Stress." International Journal of Molecular Sciences 23, no. 5 (February 25, 2022): 2562. http://dx.doi.org/10.3390/ijms23052562.

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To complete their life cycles, plants require several minerals that are found in soil. Plant growth and development can be affected by nutrient shortages or high nutrient availability. Several adaptations and evolutionary changes have enabled plants to cope with inappropriate growth conditions and low or high nutrient levels. MicroRNAs (miRNAs) have been recognized for transcript cleavage and translational reduction, and can be used for post-transcriptional regulation. Aside from regulating plant growth and development, miRNAs play a crucial role in regulating plant’s adaptations to adverse environmental conditions. Additionally, miRNAs are involved in plants’ sensory functions, nutrient uptake, long-distance root transport, and physiological functions related to nutrients. It may be possible to develop crops that can be cultivated in soils that are either deficient in nutrients or have extreme nutrient supplies by understanding how plant miRNAs are associated with nutrient stress. In this review, an overview is presented regarding recent advances in the understanding of plants’ responses to nitrogen, phosphorus, potassium, sulfur, copper, iron, boron, magnesium, manganese, zinc, and calcium deficiencies via miRNA regulation. We conclude with future research directions emphasizing the modification of crops for improving future food security.

18

Slade, A. H., R. J. Ellis, M. van den Heuvel, and T. R. Stuthridge. "Nutrient minimisation in the pulp and paper industry: an overview." Water Science and Technology 50, no. 3 (August 1, 2004): 111–22. http://dx.doi.org/10.2166/wst.2004.0175.

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This paper reviews nutrient issues within the pulp and paper industry summarising: nitrogen and phosphorus cycles within treatment systems; sources of nutrients within pulping and papermaking processes; minimising nutrient discharge; new approaches to nutrient minimisation; and the impact of nutrients in the environment. Pulp and paper industry wastewaters generally contain insufficient nitrogen and phosphorus to satisfy bacterial growth requirements. Nutrient limitation has been linked to operational problems such as sludge bulking and poor solids separation. Nutrients have been added in conventional wastewater treatment processes to ensure optimum treatment performance. Minimising the discharge of total nitrogen and phosphorus from a nutrient limited wastewater requires both optimised nutrient supplementation and effective removal of suspended solids from the treated wastewater. In an efficiently operated wastewater treatment system, the majority of the discharged nutrients are contained within the biomass. Effective solids separation then becomes the controlling step, and optimisation of secondary clarification is crucial. Conventional practice is being challenged by the regulatory requirement to reduce nitrogen and phosphorus discharge. Two recent developments in pulp and paper wastewater treatment technologies can produce discharges low in nitrogen and phosphorus whilst operating under conventionally nutrient limited conditions: i) the nutrient limited BAS process (Biofilm-Activated Sludge) which combines biofilm and activated sludge technologies under nutrient limited conditions and ii) an activated sludge process based on the use of nitrogen-fixing bacteria. Aerated stabilisation basins often operate without nutrient addition, relying on settled biomass in the benthal zone feeding back soluble nutrients, or the fixation of atmospheric nitrogen. Thus effective nutrient minimisation strategies require a more detailed understanding of nutrient cycling and utilisation. Where it is not possible to meet discharge constraints with biological treatment alone, a tertiary treatment step may be required. In setting nutrient control guidelines, consideration should be given to the nutrient limitations of the receiving environment, including other cumulative nutrient impacts on that environment. Whether an ecosystem is N or P limited should be integrated with wastewater treatment considerations in the further design and development of treatment technology and regulatory guidelines. End-of-pipe legislation alone cannot predict environmental effects related to nutrients and must be supplemented by an effects-based approach.

19

Toberman, Hannah, Chengrong Chen, and Zhihong Xu. "Rhizosphere effects on soil nutrient dynamics and microbial activity in an Australian tropical lowland rainforest." Soil Research 49, no. 7 (2011): 652. http://dx.doi.org/10.1071/sr11202.

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Via vast exchanges of energy, water, carbon, and nutrients, tropical forests are a major driving force in the regulation of Earth’s biogeochemical, hydrological, and climatic cycles. Given the critical role of rhizosphere processes in nutrient cycling, it is likely that rhizosphere processes in tropical rainforests form a major component of the biome’s interactions with global cycles. Little is known, however, about rhizospheric processes in rainforest soils. In order to investigate the influence of rhizosphere processes upon rainforest nutrient cycling, we compared the nutrient status and microbial activity of rhizospheric soil from Australian lowland tropical rainforest with that of the surrounding bulk soil. We found a marked difference in the biological and chemical nature of the rhizosphere and bulk soils. Total carbon, microbial biomass carbon, total nitrogen, soluble nitrogen, and a suite of trace element concentrations, alongside microbial respiration and the rate and diversity of carbon substrate use, were all significantly higher in the rhizosphere soil than the bulk soil. Rhizosphere soil δ15N was significantly lower than that of the bulk soil. Ratios of carbon, nitrogen, phosphorus, and sulfur differed significantly between the rhizosphere and bulk soil. These clear differences suggest that rhizosphere processes strongly influence nutrient cycling in lowland tropical rainforest, and are likely to play an important role in its interaction with global cycles. This role may be under-represented with composite sampling of rhizosphere and bulk soil. Further research is required regarding the mechanisms of rainforest rhizospheric processes and their relationship with ecosystem productivity, stability, and environmental change.

20

CAMPBELL, T. A., J. H. ELGIN JR., C. D. FOY, and J. E. McMURTREY III. "SELECTION IN ALFALFA FOR TOLERANCE TO TOXIC LEVELS OF ALUMINUM." Canadian Journal of Plant Science 68, no. 3 (July 1, 1988): 743–53. http://dx.doi.org/10.4141/cjps88-087.

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The alfalfa (Medicago sativa L.) population ’B13’ was screened through four cycles of recurrent phenotypic selection for tolerance to toxic levels of Al in growth chambers; germplasm from cycles 1 through 4 was designated B13-A11, B13-A12, B13-A13, and B13-A14, respectively. Cycles 1 and 2 were screened in Tatum clay-loam subsoil (36% Al saturation for cycle 1 and 61% Al saturation for cycle 2), and cycles 3 and 4 were screened in a modified Steinberg solution (111 μmol Al, pH 4.5). Selection was based on root growth in the first two cycles and shoot growth in the latter two cycles. Selections were intercrossed with honey bees (Apis mellifera L.) at the end of each cycle. Efficacy of the selection procedure was evaluated in pH 4.5 Steinberg solutions (Al concentration of 0 or 111 μmol), and in Tatum soil (0 or 68% Al saturation). Regression analysis indicated that significant but minimal progress was made in developing synthetics with improved vigor under Al toxic conditions. B13-A14 was among the least impaired of the entries in the ability to take up nutrients whereas AS-4 and Williamsburg (susceptible checks) were among the most impaired. It was concluded that tolerance to Al in nutrient solutions and soil could involve different mechanisms and that the screening procedure used here was much more effective in selecting for vigor than for Al tolerance. Alternative breeding approaches were proposed.Key words: Alfalfa, plant breeding, germplasm, recurrent selection, hydroponic, nutrient solution

21

Elser, James J. "Pelagic nutrient cycles: Herbivores as sources and links." Limnology and Oceanography 43, no. 6 (September 1998): 1401–2. http://dx.doi.org/10.4319/lo.1998.43.6.1401.

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22

Chin, Jason P., John P. Quinn, and John W. McGrath. "Phosphate insensitive aminophosphonate mineralisation within oceanic nutrient cycles." ISME Journal 12, no. 4 (January 16, 2018): 973–80. http://dx.doi.org/10.1038/s41396-017-0031-7.

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23

Manzoni, S., A. Porporato, P. D'Odorico, F. Laio, and I. Rodriguez-Iturbe. "Soil nutrient cycles as a nonlinear dynamical system." Nonlinear Processes in Geophysics 11, no. 5/6 (November 24, 2004): 589–98. http://dx.doi.org/10.5194/npg-11-589-2004.

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Abstract. An analytical model for the soil carbon and nitrogen cycles is studied from the dynamical system point of view. Its main nonlinearities and feedbacks are analyzed by considering the steady state solution under deterministic hydro-climatic conditions. It is shown that, changing hydro-climatic conditions, the system undergoes dynamical bifurcations, shifting from a stable focus to a stable node and back to a stable focus when going from dry, to well-watered, and then to saturated conditions, respectively. An alternative degenerate solution is also found in cases when the system can not sustain decomposition under steady external conditions. Different basins of attraction for "normal" and "degenerate" solutions are investigated as a function of the system initial conditions. Although preliminary and limited to the specific form of the model, the present analysis points out the importance of nonlinear dynamics in the soil nutrient cycles and their possible complex response to hydro-climatic forcing.

24

SUSANTO, DWI, RATNA KUSUMA, and RUDIANTO AMIRTA. "Nutrient distribution on soil and abovegroundbiomass of Macaranga gigantea five years after planting." Asian Journal of Forestry 2, no. 1 (June 1, 2018): 12–19. http://dx.doi.org/10.13057/asianjfor/r020102.

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Susanto D, Kusuma R, Amirta R. 2018. Nutrient distribution on soil and biomass of Macaranga gigantea five years after planting. Asian J For 2: 12-19. The aims of this study were to evaluate growth of M. gigantea and to calculate nutrient distribution in the soil and 5 year old M. gigantea. Soil sampling was conducted in all research plots with drill ground at a depth of 0-30 cm and 30-60 cm. The tree biomass were sampled within one stand to calculate the biomass of all the trees within a particular plot. The research findings revealed that plot 5 produces the best growth performance and the plant accumulates 2 times of N, P, K, Ca, Mg nutrients on wood, bark, branches and leaves, compared to the plants in plots 1. The most distributed nutrients in the soil were magnesium, nitrogen, calcium and phosphorus. Whereas the most acummulated nutrient in plant was potassium. The relative portion of K nutrients accumulates in the soil is quite small that is 44.18% but in stand was higher that is between 55.82%. It concluded that if the M. gigantea harvested at 5 years, it need to give attention to potassium nutrient for the next of planting cycles.

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RESENDE, CECÍLIA LEÃO PEREIRA, JULIANA BEZERRA MARTINS, FELIPE RIBEIRO ILARIA, CARLA MARIANE MACHADO DOS SANTOS, and FABRICIO RODRIGUES. "PHENOTYPIC AND GENETIC PARAMETERS ESTIMATED FOR FRESH CORN UNDER DIFFERENT NUTRIENT AVAILABILITY1." Revista Caatinga 34, no. 4 (December 2021): 752–62. http://dx.doi.org/10.1590/1983-21252021v34n402rc.

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ABSTRACT The objective of this work was to estimate and compare phenotypic and genetic parameters after three cycles of intrapopulation recurrent selection for fresh corn grown under three nutrient availability conditions. Three experiments derived from the same population (MV-003) were conducted to assess the ability of progenies to absorb nutrients, one under adequate fertilization (control; MV-006), one under low nitrogen availability (N; MV-006N), and one under low phosphorus availability (P; MV-006P). The experiments were carried out in randomized blocks, with 64 half-sib progenies and three replications for each nutritional condition. Chlorophyll index, plant height, ear insertion, ear diameter, ear length, unhusked ear yield, and marketable husked ear were evaluated. The populations showed variability for the three nutrient availability conditions. The variability reduced after only three selection cycles; thus, evaluating a higher number of half-sib progenies, above 64, under low N and P availability is indicated. The rates used to identify the most efficient progenies in breeding programs should be close to the appropriate one, with a slow reduction after the selection cycles. The variability will be thus maintained, with a greater possibility of identifying more promising progenies. In addition, the frequency of favorable alleles increases more gradually and effectively. The N and P rate of 60 kg ha-1 is not indicated as a critical level for the initial phase of the program.

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RUSSELLE, M. P., and R. L. McGRAW. "NUTRIENT STRESS IN BIRDSFOOT TREFOIL." Canadian Journal of Plant Science 66, no. 4 (October 1, 1986): 933–46. http://dx.doi.org/10.4141/cjps86-115.

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Birdsfoot trefoil (Lotus corniculatus L.) is often grown on poorly drained, low fertility, and low pH soils under marginal management. The objective of this research was to document several aspects of single nutrient stresses in birdsfoot trefoil. Plants were grown hydroponically in the glasshouse through two vegetative cycles and one reproductive growth cycle. Nutrient deficient treatments included P, K, Ca, Mg, S, B, Fe, Mn, Zn, Cu and Mo; toxicity treatments included B, Mn, Zn, Cu and Mo. Dry mass of shoots, shoot branching, and leaf area were typically lower in stressed plants than in plants grown in complete nutrient solution and specific leaf mass was generally larger in stressed plants. Nodule function and appearance were more severely affected by macronutrient than by micronutrient (except B) deficiencies. A deficiency or excess of a given nutrient often increased concentrations of other nutrients, but concentrations of some elements also decreased in response to a stress in another. In a few instances, concentrations of a nutrient differed from the complete treatment in an opposite manner in shoots than in roots. Seed yield and yield components were less frequently affected by nutrient stress than were herbage yields. Visual symptoms were generally similar to those of alfalfa (Medicago sativa) and the clovers (Trifolium spp.).Key words: Lotus corniculatus L., mineral nutrition, nutrient deficiency, nutrient toxicity, hydroponic solution culture, birdsfoot trefoil

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Thum, Tea, Silvia Caldararu, Jan Engel, Melanie Kern, Marleen Pallandt, Reiner Schnur, Lin Yu, and Sönke Zaehle. "A new model of the coupled carbon, nitrogen, and phosphorus cycles in the terrestrial biosphere (QUINCY v1.0; revision 1996)." Geoscientific Model Development 12, no. 11 (November 20, 2019): 4781–802. http://dx.doi.org/10.5194/gmd-12-4781-2019.

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Abstract. The dynamics of terrestrial ecosystems are shaped by the coupled cycles of carbon, nitrogen, and phosphorus, and these cycles are strongly dependent on the availability of water and energy. These interactions shape future terrestrial biosphere responses to global change. Here, we present a new terrestrial ecosystem model, QUINCY (QUantifying Interactions between terrestrial Nutrient CYcles and the climate system), which has been designed from scratch to allow for a seamless integration of the fully coupled carbon, nitrogen, and phosphorus cycles with each other and also with processes affecting the energy and water balances in terrestrial ecosystems. This new model includes (i) a representation of plant growth which separates source (e.g. photosynthesis) and sink (growth rate of individual tissues, constrained by temperature and the availability of water and nutrients) processes; (ii) the acclimation of many ecophysiological processes to meteorological conditions and/or nutrient availability; (iii) an explicit representation of vertical soil processes to separate litter and soil organic matter dynamics; (iv) a range of new diagnostics (leaf chlorophyll content; 13C, 14C, and 15N isotope tracers) to allow for a more in-depth model evaluation. In this paper, we present the model structure and provide an assessment of its performance against a range of observations from global-scale ecosystem monitoring networks. We demonstrate that QUINCY v1.0 is capable of simulating ecosystem dynamics across a wide climate gradient, as well as across different plant functional types. We further provide an assessment of the sensitivity of key model predictions to the model's parameterisation. This work lays the ground for future studies to test individual process hypotheses using the QUINCY v1.0 framework in the light of ecosystem manipulation observations, as well as global applications to investigate the large-scale consequences of nutrient-cycle interactions for projections of terrestrial biosphere dynamics.

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Thompson, SK, and JB Cotner. "P-limitation drives changes in DOM production by aquatic bacteria." Aquatic Microbial Ecology 85 (August 6, 2020): 35–46. http://dx.doi.org/10.3354/ame01940.

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Heterotrophic bacteria are key biogeochemical regulators in freshwater systems. Through both decomposition and production of organic matter, bacteria link multiple biogeochemical cycles together. While there has been a significant amount of work done on understanding the role of microbes in the aquatic carbon cycle, important linkages with other biogeochemical cycles will require more information about how organic matter transformations impact other nutrients, such as phosphorus. In this study, we conducted a culture-based laboratory experiment to examine the production of dissolved organic matter (DOM) by heterotrophic bacteria under varied nutrient conditions. In addition to quantifying the production of dissolved organic carbon (DOC), we also measured the production of dissolved organic phosphorus (DOP) and characterized the microbially produced organic matter using optical properties. Results demonstrated that measurable amounts of DOC and DOP were produced by heterotrophic bacteria under nutrient regimes ranging from carbon-limitation to strong phosphorus-limitation. Additionally, optical characterization of DOM revealed that the organic matter produced by bacteria grown under high phosphorus conditions was highly aromatic with similar optical properties to terrestrially derived organic matter. Overall, these findings suggest that heterotrophic bacteria can be important producers of organic matter in freshwaters and that continued trends of increased nutrient concentrations (eutrophication) may fundamentally change the composition of microbially produced organic matter in freshwater systems.

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Cerrillo, Míriam, Laura Burgos, Joan Noguerol, Victor Riau, and August Bonmatí. "Ammonium and Phosphate Recovery in a Three Chambered Microbial Electrolysis Cell: Towards Obtaining Struvite from Livestock Manure." Processes 9, no. 11 (October 27, 2021): 1916. http://dx.doi.org/10.3390/pr9111916.

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Ammonia and phosphate, which are present in large quantities in waste streams such as livestock manure, are key compounds in fertilization activities. Their recovery will help close natural cycles and take a step forward in the framework of a circular economy. In this work, a lab-scale three-chambered microbial electrolysis cell (MEC) has been operated in continuous mode for the recovery of ammonia and phosphate from digested pig slurry in order to obtain a nutrient concentrated solution as a potential source of fertilizer (struvite). The maximum average removal efficiencies for ammonium and phosphate were 20% ± 4% and 36% ± 10%, respectively. The pH of the recovered solution was below 7, avoiding salt precipitation in the reactor. According to Visual MINTEQ software modelling, an increase of pH value to 8 outside the reactor would be enough to recover most of the potential struvite (0.21 mmol L−1 d−1), while the addition of up to 0.2 mM of magnesium to the nutrient recovered solution would enhance struvite production from 5.6 to 17.7 mM. The application of three-chambered MECs to the recovery of nutrients from high strength wastewater is a promising technology to avoid ammonia production through industrial processes or phosphate mineral extraction and close nutrient natural cycles.

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Pérez-Huerta, Alberto, and Nathan D. Sheldon. "Pennsylvanian sea level cycles, nutrient availability and brachiopod paleoecology." Palaeogeography, Palaeoclimatology, Palaeoecology 230, no. 3-4 (January 2006): 264–79. http://dx.doi.org/10.1016/j.palaeo.2005.07.020.

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Large, Ross R., Jacqueline A. Halpin, Elena Lounejeva, Leonid V. Danyushevsky, Valeriy V. Maslennikov, Daniel Gregory, Patrick J. Sack, et al. "Cycles of nutrient trace elements in the Phanerozoic ocean." Gondwana Research 28, no. 4 (December 2015): 1282–93. http://dx.doi.org/10.1016/j.gr.2015.06.004.

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Rastetter, E. B., R. D. Yanai, R. Q. Thomas, M. A. Vadeboncoeur, T. J. Fahey, M. C. Fisk, B. L. Kwiatkowski, and S. P. Hamburg. "Recovery from disturbance requires resynchronization of ecosystem nutrient cycles." Ecological Applications 23, no. 3 (April 2013): 621–42. http://dx.doi.org/10.1890/12-0751.1.

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Barber, Steven T., Jingjing Yin, Kathleen Draper, and Thomas A. Trabold. "Closing nutrient cycles with biochar- from filtration to fertilizer." Journal of Cleaner Production 197 (October 2018): 1597–606. http://dx.doi.org/10.1016/j.jclepro.2018.06.136.

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Golterman, H. L. "Preface to the symposium ?Nutrient Cycles, A Joy Forever?" Hydrobiologia 315, no. 1 (November 1995): 7–8. http://dx.doi.org/10.1007/bf00028625.

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Hammes, F., Y. Kalogo, and W. Verstraete. "Anaerobic digestion technologies for closing the domestic water, carbon and nutrient cycles." Water Science and Technology 41, no. 3 (February 1, 2000): 203–11. http://dx.doi.org/10.2166/wst.2000.0073.

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Sustainable wastewater treatment requires that household wastewater is collected and treated separately from industrial wastewater and rainwater run-offs. This separate treatment is, however, still inadequate, as more than 70% of the nutrients and much of the chemical oxygen demand (COD) and potential pathogens of a domestic sewage system are confined to the few litres of black water (faeces, urine and toilet water). Whilst grey water can easily be filter treated and re-used for secondary household purposes, black water requires more intensive treatment due to its high COD and microbial (pathogens) content. Recently developed vacuum/dry toilets produce a nutrient rich semi-solid waste stream, which, with proper treatment, offers the possibility of nutrient, carbon, water and energy recovery. This study investigates the terrestrial applicability of Life Support System (LSS) concepts as a framework for future domestic waste management. The possibilities of treating black water together with other types of human-generated solid waste (biowastes/mixed wastes) in an anaerobic reactor system at thermophilic conditions, as well as some post treatment alternatives for product recovery and re-use, are considered. Energy can partially be recovered in the form of biogas produced during anaerobic digestion. The system is investigated in the form of theoretical mass balances, together with an assessment of the current feasibility of this technology and other post-treatment alternatives.

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Bonachela, J. A., S. D. Allison, A. C. Martiny, and S. A. Levin. "A model for variable phytoplankton stoichiometry based on cell protein regulation." Biogeosciences 10, no. 6 (June 27, 2013): 4341–56. http://dx.doi.org/10.5194/bg-10-4341-2013.

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Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. When different species compete, the existence of a wide co-limitation zone implies a more complex pattern of coexistence and exclusion compared to previous model predictions. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.

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Bonachela, J. A., S. D. Allison, A. C. Martiny, and S. A. Levin. "A model for variable phytoplankton stoichiometry based on cell protein regulation." Biogeosciences Discussions 10, no. 2 (February 21, 2013): 3241–79. http://dx.doi.org/10.5194/bgd-10-3241-2013.

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Abstract. The elemental ratios of marine phytoplankton emerge from complex interactions between the biotic and abiotic components of the ocean, and reflect the plastic response of individuals to changes in their environment. The stoichiometry of phytoplankton is, thus, dynamic and dependent on the physiological state of the cell. We present a theoretical model for the dynamics of the carbon, nitrogen and phosphorus contents of a phytoplankton population. By representing the regulatory processes controlling nutrient uptake, and focusing on the relation between nutrient content and protein synthesis, our model qualitatively replicates existing experimental observations for nutrient content and ratios. The population described by our model takes up nutrients in proportions that match the input ratios for a broad range of growth conditions. In addition, there are two zones of single-nutrient limitation separated by a wide zone of co-limitation. Within the co-limitation zone, a single point can be identified where nutrients are supplied in an optimal ratio. The existence of a wide co-limitation zone affects the standard picture for species competing for nitrogen and phosphorus, which shows here a much richer pattern. However, additional comprehensive laboratory experiments are needed to test our predictions. Our model contributes to the understanding of the global cycles of oceanic nitrogen and phosphorus, as well as the elemental ratios of these nutrients in phytoplankton populations.

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Elliott, Jane. "Evaluating the potential contribution of vegetation as a nutrient source in snowmelt runoff." Canadian Journal of Soil Science 93, no. 4 (September 2013): 435–43. http://dx.doi.org/10.4141/cjss2012-050.

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Elliott, J. 2013. Evaluating the potential contribution of vegetation as a nutrient source in snowmelt runoff. Can. J. Soil Sci. 93: 435–443. On the Canadian prairies, most nutrient transport to surface waters takes place during snowmelt. The potential for a range of 11 residue types to release nitrogen (N), phosphorus (P) and carbon (C) was assessed by snowmelt simulation. Interactions between soils and residues were measured for two contrasting residues. Samples (taken in late fall) were frozen prior to snowmelt simulations that consisted of three diurnal temperature cycles from −5°C to +9°C followed by a final melt at +5°C. Releases of total and total dissolved P (TP and TDP), total dissolved N (TDN), and dissolved organic C (DOC) during simulated snowmelt were greater from actively growing residues than from crop stubble and were significantly related to plant moisture and nutrient contents. Nutrient release from wheat stubble (WS) was statistically similar to that from the underlying surface soil but releases of P and ammonia (NH3) from winter wheat (WW) were at least four times greater than for the corresponding soil. When combined samples of residue and soil were tested, releases of most nutrients were less than when the residue and soil were tested separately. Potential release of nutrients from vegetation is a factor for consideration in the design of practices to reduce nutrient transport.

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Reetsch, Anika, Kai Schwärzel, Christina Dornack, Shadrack Stephene, and Karl-Heinz Feger. "Optimising Nutrient Cycles to Improve Food Security in Smallholder Farming Families—A Case Study from Banana-Coffee-Based Farming in the Kagera Region, NW Tanzania." Sustainability 12, no. 21 (November 2, 2020): 9105. http://dx.doi.org/10.3390/su12219105.

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In East Africa, soil nutrient depletion and low yields jeopardise the food security of smallholder farming families and exacerbate poverty. The main reasons for the depletion of soil nutrients are overuse due to population growth, limited land, and increasing uncertainty in agricultural production caused by climate change. This study aims to analyse and optimise nutrient flows and stocks in the homegardens of smallholder banana-coffee-based farming systems in the Kagera region in NW Tanzania. The plant nutrients nitrogen (N), phosphorus (P), and potassium (K) in plant-based biomass and organic farm waste are under investigation. We used data from a farm household survey (150 households) and from focus group discussions with 22 trainers who had been training about 750 farm households in sustainable land management (SLM) at a local farmer field school. In total, we identified six farm household types and calculated a nutrient balance (NB) for the homegardens of each household type. The NB was calculated for the following five management scenarios: S0: business as usual; S1: the use of 80% of the available human urine; S2: the incorporation of 0.5 t yr−1 of the herbaceous legume species Crotalaria grahamiana into the soil; S3: the production of 5 m3 yr−1 CaSa-compost (human excreta and biochar) and its application on 600 m2 land; and S4: a combination of S1, S2, and S3. The results show that the NB varies considerably depending on whether farmers have implemented the SLM training, apply nutrient-preserving manure collection and storage methods, and purchase fodder (imported nutrients), or whether they do not collect manure or do not purchase fodder. Trained farm households are more likely to have a positive NB than untrained households because they have already improved the nutrient management of their farms through the successful implementation of SLM practices. Untrained households would improve the NB in their homegardens under all management scenarios. However, the NB depends on labour-intensive manure collection and compost production, labour shortages, prolonged dry seasons, and socio-economic imbalances. As long as these constraints remain, nutrient deficiencies will not be overcome with mineral fertilisers alone, because soils have to be further enriched with organic matter first. In this paper, we also emphasise the importance of the system boundary, because only a complete NB can give an estimate of actual nutrient removal and the resulting nutrient demand (including removals by fodder and trees). Further improvements in the SLM training may be achieved by (i) measuring the current nutrient status of soils, (ii) analysing the need for the coexistence of free-range livestock on the grassland and zero-grazing in trained households, and (iii) conducting an in-depth analysis of the socio-economic differences between successful and unsuccessful households. In conclusion, if smallholder farmers were to integrate further improved SLM training and optimised nutrient management (S1 to S4), we assume that the NB would turn positive. Last but not least, the SLM training by the farmer field school may serve as a best-practice example for training and policy recommendations made by government institutions.

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Van Wambeke, France, Vincent Taillandier, Karine Desboeufs, Elvira Pulido-Villena, Julie Dinasquet, Anja Engel, Emilio Marañón, Céline Ridame, and Cécile Guieu. "Influence of atmospheric deposition on biogeochemical cycles in an oligotrophic ocean system." Biogeosciences 18, no. 20 (October 22, 2021): 5699–717. http://dx.doi.org/10.5194/bg-18-5699-2021.

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Abstract. The surface mixed layer (ML) in the Mediterranean Sea is a well-stratified domain characterized by low macronutrients and low chlorophyll content for almost 6 months of the year. In this study we characterize the biogeochemical cycling of nitrogen (N) in the ML by analyzing simultaneous in situ measurements of atmospheric deposition, nutrients in seawater, hydrological conditions, primary production, heterotrophic prokaryotic production, N2 fixation and leucine aminopeptidase activity. Dry deposition was continuously measured across the central and western open Mediterranean Sea, and two wet deposition events were sampled, one in the Ionian Sea and one in the Algerian Basin. Along the transect, N budgets were computed to compare the sources and sinks of N in the mixed layer. In situ leucine aminopeptidase activity made up 14 % to 66 % of the heterotrophic prokaryotic N demand, and the N2 fixation rate represented 1 % to 4.5 % of the phytoplankton N demand. Dry atmospheric deposition of inorganic nitrogen, estimated from dry deposition of nitrate and ammonium in aerosols, was higher than the N2 fixation rates in the ML (on average 4.8-fold). The dry atmospheric input of inorganic N represented a highly variable proportion of biological N demand in the ML among the stations, 10 %–82 % for heterotrophic prokaryotes and 1 %–30 % for phytoplankton. As some sites were visited on several days, the evolution of biogeochemical properties in the ML and within the nutrient-depleted layers could be followed. At the Algerian Basin site, the biogeochemical consequences of a wet dust deposition event were monitored through high-frequency sampling. Notably, just after the rain, nitrate was higher in the ML than in the nutrient-depleted layer below. Estimates of nutrient transfer from the ML into the nutrient-depleted layer could explain up to a third of the nitrate loss from the ML. Phytoplankton did not benefit directly from the atmospheric inputs into the ML, probably due to high competition with heterotrophic prokaryotes, also limited by N and phosphorus (P) availability at the time of this study. Primary producers decreased their production after the rain but recovered their initial state of activity after a 2 d lag in the vicinity of the deep chlorophyll maximum layer.

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Trong Hung, Dao, Harold Hughes, Markus Keck, and Daniela Sauer. "Rice-Residue Management Practices of Smallholder Farms in Vietnam and Their Effects on Nutrient Fluxes in the Soil-Plant System." Sustainability 11, no. 6 (March 19, 2019): 1641. http://dx.doi.org/10.3390/su11061641.

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In Vietnam, approximately 39 million tons of rice (Oryza sativa) residues accrue every year. In this study, we quantified soil nutrient balances of paddy rice fields under different crop-residue management practices in northern Vietnam. On twelve farms, we calculated nutrient balances for the four prevalent rice-residue management practices, i.e., (1) direct incorporation of rice residues into the soil, (2) application of rice-residue compost, (3) burning of rice residues on the field, and (4) the use of rice residues as fodder for livestock. Soils under practices (1) to (3) showed a positive nutrient balance, which indicates that soil fertility can be maintained under these practices and that the amounts of chemical fertilizers can be considerably reduced. If not, there is a risk of eutrophication in the surrounding surface waterbodies. Practice (4), in contrast, resulted in a negative nutrient balance, which indicates the need for returning nutrients to the soils. From our findings we conclude that knowledge about the effects of rice-residue management practices on nutrient cycles may help to optimize the use of fertilizers, resulting in a more sustainable form of agriculture.

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Ezzat, Leïla, Jean-François Maguer, Renaud Grover, and Christine Ferrier-Pagès. "New insights into carbon acquisition and exchanges within the coral–dinoflagellate symbiosis under NH 4 + and NO 3 − supply." Proceedings of the Royal Society B: Biological Sciences 282, no. 1812 (August 7, 2015): 20150610. http://dx.doi.org/10.1098/rspb.2015.0610.

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Anthropogenic nutrient enrichment affects the biogeochemical cycles and nutrient stoichiometry of coastal ecosystems and is often associated with coral reef decline. However, the mechanisms by which dissolved inorganic nutrients, and especially nitrogen forms (ammonium versus nitrate) can disturb the association between corals and their symbiotic algae are subject to controversial debate. Here, we investigated the coral response to varying N : P ratios, with nitrate or ammonium as a nitrogen source. We showed significant differences in the carbon acquisition by the symbionts and its allocation within the symbiosis according to nutrient abundance, type and stoichiometry. In particular, under low phosphate concentration (0.05 µM), a 3 µM nitrate enrichment induced a significant decrease in carbon fixation rate and low values of carbon translocation, compared with control conditions (N : P = 0.5 : 0.05), while these processes were significantly enhanced when nitrate was replaced by ammonium. A combined enrichment in ammonium and phosphorus (N : P = 3 : 1) induced a shift in nutrient allocation to the symbionts, at the detriment of the host. Altogether, these results shed light into the effect of nutrient enrichment on reef corals. More broadly, they improve our understanding of the consequences of nutrient loading on reef ecosystems, which is urgently required to refine risk management strategies.

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Alongi, Daniel M. "Macro- and Micronutrient Cycling and Crucial Linkages to Geochemical Processes in Mangrove Ecosystems." Journal of Marine Science and Engineering 9, no. 5 (April 22, 2021): 456. http://dx.doi.org/10.3390/jmse9050456.

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High mangrove productivity is sustained by rapid utilization, high retention efficiency and maximum storage of nutrients in leaves, roots, and soils. Rapid microbial transformations and high mineralization efficiencies in tandem with physiological mechanisms conserve scarce nutrients. Macronutrient cycling is interlinked with micronutrient cycling; all nutrient cycles are linked closely to geochemical transformation processes. Mangroves can be N-, P-, Fe-, and Cu-limited; additions of Zn and Mo stimulate early growth until levels above pristine porewater concentrations induce toxicity. Limited nutrient availability is caused by sorption and retention onto iron oxides, clays, and sulfide minerals. Little N is exported as immobilization is the largest transformation process. Mn and S affect N metabolism and photosynthesis via early diagenesis and P availability is coupled to Fe-S redox oscillations. Fe is involved in nitrification, denitrification and anammox, and Mo is involved in NO3− reduction and N2-fixation. Soil Mg, K, Mn, Zn and Ni pool sizes decrease as mangrove primary productivity increases, suggesting increasing uptake and more rapid turnover than in less productive forests. Mangroves may be major contributors to oceanic Mn and Mo cycles, delivering 7.4–12.1 Gmol Mn a−1 to the ocean, which is greater than global riverine input. The global Mo import rate by mangroves corresponds to 15–120% of Mo supply to the oceanic Mo budget.

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Corbett, D. R. "Resuspension and estuarine nutrient cycling: insights from the Neuse River Estuary." Biogeosciences Discussions 7, no. 2 (April 16, 2010): 2767–98. http://dx.doi.org/10.5194/bgd-7-2767-2010.

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Abstract. For at least the past several decades, North Carolina's Neuse River Estuary (NRE) has been subject to water quality problems relating to increased eutrophication. Research studies initiated in the past several years have addressed the complex nutrient cycles in this system. Most of this research, however, is concerned with the nutrient processes of the water column and the passive diffusion processes of the benthic sedimentary environment. Resuspension of bottom sediments, by bioturbation, tides, or wind-generated waves, may have a significant effect on the flux of nutrients in an estuarine system These processes can result in the advective transport of sediment porewater, rich with nitrogen, phosphorus and carbon, into the water column. Thus, estimates of nutrient and carbon inputs from the sediments may be too low. This study focused on the potential change in porewater and bottom water nutrient concentrations associated with measured resuspension events. Previous research used short-lived radionuclides and meteorological data to characterize the sediment dynamics of the benthic system of the estuary. These techniques in conjunction with the presented porewater inventories allowed evaluation of the depth to which sediments have been disturbed and the advective flux of nutrients to the water column. The largest removal episode occurred in the lower NRE as the result of a wind event and was estimated that the top 2.2 cm of sediment and corresponding porewater were removed. NH4+ advective flux (resuspended) was 2 to 6 times greater than simply diffusion. Phosphate fluxes were estimated to be 15 times greater than the benthic diffusive flux. Bottom water conditions with elevated NH4+ and PO43− indicate that nutrients stored in the sediments continue to play an important role in overall water quality and this study suggests that the advective flux of nutrients to the water column is critical to understand estuarine nutrient cycling.

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Giang, P. H., H. Harada, S. Fujii, N. P. H. Lien, H. T. Hai, P. N. Anh, and S. Tanaka. "Transition of fertilizer application and agricultural pollution loads: a case study in the Nhue-Day River basin." Water Science and Technology 72, no. 7 (June 16, 2015): 1072–81. http://dx.doi.org/10.2166/wst.2015.312.

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Rapid socio-economic development in suburban areas of developing countries has induced changes in agricultural waste and nutrient management, resulting in water pollution. The study aimed at estimating agricultural nutrient cycles and their contribution to the water environment. A material flow model of nitrogen (N) and phosphorus (P) was developed focusing on agricultural activities from 1980 to 2010 in Trai hamlet, an agricultural watershed in Nhue-Day River basin, Vietnam. The model focused on the change in household management of human excreta and livestock excreta, and chemical fertilizer consumption. The results showed that the proportion of nutrients from compost/manure applied to paddy fields decreased from 85 to 41% for both N and P between 1980 and 2010. The nutrient inputs derived from chemical fertilizer decreased 6% between 1980 and 2000 for both N and P. Then, these nutrients increased 1.4 times for N and 1.2 times for P from 2000 to 2010. As of 2010, the total inputs to paddy fields have amounted to 435 kg-N/ha/year and 90 kg-P/ha/year. Of these nutrient inputs, 40% of N and 65% of P were derived from chemical fertilizer. Thirty per cent (30%) of total N input was discharged to the water bodies through agricultural runoff and 47% of total P input accumulated in soil.

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Stadmark, J., and D. J. Conley. "Mussel farming as a nutrient reduction measure in the Baltic Sea: Consideration of nutrient biogeochemical cycles." Marine Pollution Bulletin 62, no. 7 (July 2011): 1385–88. http://dx.doi.org/10.1016/j.marpolbul.2011.05.001.

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Salonius, Peter. "Will forestry follow agriculture toward unsustainable soil depletion?" Forestry Chronicle 83, no. 3 (May 1, 2007): 375–77. http://dx.doi.org/10.5558/tfc83375-3.

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Human settlement has increased food production by progressively converting complex, self-managing natural ecosystems with tight nutrient cycles into simplified, intensively-managed agricultural ecosystems that are subject to nutrient leaching. Conventional stem wood forest harvesting is now poised to be replaced by intensive harvesting of biomass to substitute for increasingly scarce non renewable fossil fuels. Removal of nutrient-rich forest biomass (harvesting slash) can not be sustained in the long term. Key words: soil nutrient depletion, biomass harvesting, site productivity

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Leite, Fernando Palha, Ivo Ribeiro Silva, Roberto Ferreira Novais, Nairam Félix de Barros, and Júlio César Lima Neves. "Alterations of soil chemical properties by eucalyptus cultivation in five regions in the Rio Doce Valley." Revista Brasileira de Ciência do Solo 34, no. 3 (June 2010): 821–31. http://dx.doi.org/10.1590/s0100-06832010000300024.

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Little is currently known about modifications in edaphic characteristics caused by short-rotation eucalyptus and the impacts of these alterations on the sustainability of eucalyptus wood production. This study was carried out to identify theses changes at five sites of eucalyptus plantation in the region of the Rio Doce Valley, state of Minas Gerais, Brazil. Areas with more than three previous eucalyptus cycles, adjacent to pasture land or native forest, were chosen. Soil samples were collected and soil fertility analyzed by routine methods and other fractionation methods in order to measure alterations in the K, Ca and Mg contents as a consequence of eucalyptus cultivation. In the eucalyptus areas, reductions in the exchangeable Ca2+, Mg2+ and K+ contents and pH were observed and increased Al3+ and H + Al contents. Of all nutrients, only P contents (Mehlich-1 P) increased in the eucalyptus areas. The reduction in exchangeable forms and in medium-term soil nutrient pools indicates the need for higher nutrient rates than the currently applied in order to prevent nutritional limitations and soil nutrient exhaustion. After several eucalyptus rotations there was a recovery in the SOM content in comparison to degraded pasture soils, although not to the level of the native forest soil. The positive correlation between effective CEC and medium-term non-exchangeable Ca, Mg and K with SOM emphasizes the need for adequate fertilizer and plant residue management to sustain or even increase forest productivity in future cycles.

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Linz, Alexandra M., Shaomei He, Sarah L. R. Stevens, Karthik Anantharaman, Robin R. Rohwer, Rex R. Malmstrom, Stefan Bertilsson, and Katherine D. McMahon. "Freshwater carbon and nutrient cycles revealed through reconstructed population genomes." PeerJ 6 (December 10, 2018): e6075. http://dx.doi.org/10.7717/peerj.6075.

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Although microbes mediate much of the biogeochemical cycling in freshwater, the categories of carbon and nutrients currently used in models of freshwater biogeochemical cycling are too broad to be relevant on a microbial scale. One way to improve these models is to incorporate microbial data. Here, we analyze both genes and genomes from three metagenomic time series and propose specific roles for microbial taxa in freshwater biogeochemical cycles. Our metagenomic time series span multiple years and originate from a eutrophic lake (Lake Mendota) and a humic lake (Trout Bog Lake) with contrasting water chemistry. Our analysis highlights the role of polyamines in the nitrogen cycle, the diversity of diazotrophs between lake types, the balance of assimilatory vs. dissimilatory sulfate reduction in freshwater, the various associations between types of phototrophy and carbon fixation, and the density and diversity of glycoside hydrolases in freshwater microbes. We also investigated aspects of central metabolism such as hydrogen metabolism, oxidative phosphorylation, methylotrophy, and sugar degradation. Finally, by analyzing the dynamics over time in nitrogen fixation genes and Cyanobacteria genomes, we show that the potential for nitrogen fixation is linked to specific populations in Lake Mendota. This work represents an important step towards incorporating microbial data into ecosystem models and provides a better understanding of how microbes may participate in freshwater biogeochemical cycling.

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Sfriso, A., B. Pavoni, A. Marcomini, and A. A. Orio. "Macroalgae, Nutrient Cycles, and Pollutants in the Lagoon of Venice." Estuaries 15, no. 4 (December 1992): 517. http://dx.doi.org/10.2307/1352394.

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