Iron Fertilization Research Articles

Dissolved and particulate iron redox speciation during the LOHAFEX fertilization experiment.

The redox speciation of iron was determined during the iron fertilization LOHAFEX and for the first time, the chemiluminescence assay of filtered and unfiltered samples was systematically compared. We hypothesize that higher chemiluminescence in unfiltered samples was caused by Fe(II) adsorbed onto biological particles. Dissolved and particulate Fe(II) increased in the mixed layer steadily 6-fold during the first two weeks and decreased back to initial levels by the end of LOHAFEX. Both Fe(II) forms did not show diel cycles downplaying the role of photoreduction. The chemiluminescence of unfiltered samples across the patch boundaries showed strong gradients, correlated significantly to biomass and the photosynthetic efficiency and were higher at night, indicative of a biological control. At 150m deep, a secondary maximum of dissolved Fe(II) was associated with maxima of nitrite and ammonium despite high oxygen concentrations. We hypothesize that during LOHAFEX, iron redox speciation was mostly regulated by trophic interactions.

Foliar Application of Different Iron Sources Improves Morpho-Physiological Traits and Nutritional Quality of Broad Bean Grown in Sandy Soil.

Nano-fertilizers are a new tool that can be used to address plant production challenges, and it addresses such nutrient deficiencies through smart agriculture approaches. Iron (Fe) is a vital element for several metabolic and physiological processes; however, Fe deficiency is common in poorly fertile soils (sand soil) and in arid areas. Therefore, additional research is required to select the most efficient form of iron absorbance. This research was implemented on broad bean plants (Vicia faba L. var. major Harz) to examine the impact of three iron sources: nano-iron (FeNPs, T1), iron sulfate (T2), and chelated iron (T3) as a foliar spray on the morphological properties, physiological attributes, and nutritional status of these plants compared to the untreated plants (control). The obtained results showed that foliar spraying with FeNPs, chelated iron and sulphate iron fertilizers increased plant height by 35.01%, 26.2, and 20.4%; leaf area by 38.8%, 18.3%, and 8.1%; the fresh weight of the plant by 47%, 32.8%, and 7.3%; the dry weight of the plant by 52.9%, 37.3%, and 11.2%; and the number of branches by 47%, 31.3%, and 25.6 %, respectively, compared to the control treatment (CT). Furthermore, the application of FeNPs, chelated iron, and sulphate iron fertilizers improved the number of pods by 47.9%, 24.8%, and 6.1%; the number of seeds by 32.8%, 7.9%, and 2.8%; and seed weight by 20.8%, 9.1%, and 5.4%, compared to control treatment (CT). Additionally, foliar application of FeNPs showed the highest values of photosynthesis rate (Pn), water-use efficiency (WUE), total chlorophyll, and phytohormones (IAA, GA3) compared to all the other treatments. The anatomical structure revealed an enhancement of leaf size and thickness (epidermis cells and mesophyll tissue) affected by FeNPs treatment compared to other treatments. Foliar application of FeNPs also improved the total content of carbohydrates, crude protein, element content (N, P, K, Ca, Na, Fe, Zn, Mn, and Cu), and some amino acids such as lysine, arginine, phenylalanine, isoleucine, and tyrosine in the seeds of broad beans. Based on the above results, the maximum values of all tested measurements were observed when FeNPs were used as the foliar spraying followed by chelated and sulphate iron fertilizers. Therefore, these findings suggest that using FeNPs, as a foliar treatment, could be a promising strategy for reducing the Fe deficiency in sandy soil and enhancing plant growth, pod yield, and pod quality of broad bean plants in addition to being environmentally favored in arid areas.

Effects of Iron Rates on Growth and Development of Young Huanglongbing-affected Citrus Trees in Florida

Essential nutrients for citrus [‘Bingo’ (Citrus reticulata, Blanco)] production are important for different functions, including photosynthesis, resistance to disease, and productivity. During the past 15 to 20 years, citrus production in Florida has significantly declined as a result of the devastating citrus greening disease also called huanglongbing (HLB). Therefore, a greenhouse study was conducted for 2 years, starting in 2018, at the University of Florida/Institute of Food and Agricultural Sciences Citrus Research and Education Center in Florida to evaluate the effect of varying rates of iron on the growth and development of 2-year-old HLB-affected ‘Bingo’ (Citrus reticulata, Blanco) trees on Kuharske citrange rootstock. Four treatments were used in a randomized complete block (HLB status) design with seven single tree replicates for each treatment. The treatments applied were 0.0 (control), 5.6 (standard fertilization, lx), 11.2 (2x), and 22.4 (4x) kg⋅ha−1 iron on HLB-affected and healthy (non-HLB) citrus trees. Data including trunk diameter, tree height, and leaf samples were collected, processed, and analyzed at 3-month intervals for 2 years. At the end of the second year, trees were destructively sampled and processed as above-ground and below-ground biomass. Tree heights were different among iron rates of HLB-affected trees (P < 0.001); however, they were similar for non-HLB trees for both years. Higher average trunk diameters (P < 0.001) were observed for HLB-affected trees that received the 2x rate compared with the 1x rate and the control. In 2019, non-HLB trees showed 13% to 40% higher iron concentrations in leaves than HLB-affected trees. However, leaf iron concentrations were comparable for HLB-affected and non-HLB trees in 2020. Above-ground biomass for HLB-affected trees had between 33% and 44% more biomass (P < 0.01) than below-ground biomass for the corresponding iron fertilization. Iron accumulation correlated positively with all studied nutrients in the above-ground parts for both HLB-affected and non-HLB trees. A 95% confidence interval at which total biomass was nearly maximum corresponded to an iron rate of 9.6 to 11.8 kg⋅ha−1, which was close to the 2x rate. Therefore, soil iron application using the aforementioned rates may be appropriate for better growth and development of young HLB-affected trees.

Use of organic fertilizers in solar photo-Fenton process as potential technology to remove pineapple processing wastewater in Costa Rica.

Background: This work studied the use of the organic fertilizers DTPA-Fe and EDDS-Fe as iron chelates for solar driven photo-Fenton process at natural pH. This process was proposed to investigate its performance on removing a mixture of agrochemicals (propiconazole, imidacloprid and diuron) from pineapple processing wastewater to obtain a suitable effluent to be reused in the agricultural sector. Methods: Experiments were carried out in a solar simulator with a stirred cylindric photoreactor, with a volume of 150 mL and controlled temperature (20°C). The first set of experiments was carried out with ultrapure water to determine optimal iron and H 2O 2 concentrations. The second was performed with simulated wastewater of pineapple processing. Results: The optimized operational conditions for both iron complexes were 10 mg L -1 of Fe (III) and 25 mg L -1 of H 2O 2, since more than 80% of micropollutants (MP) (at an initial concentration of 1 mg L -1 of each compound) were removed in only 20 min with both DTPA-Fe and EDDS-Fe. The effect of organic matter and inorganic salts on radicals scavenging and chelates stability was also investigated in the experiments performed with synthetic pineapple processing wastewater. The results disclosed differences depending on the iron complex. Nitrites were the principal component influencing the tests carried out with EDDS-Fe. While carbonates at low concentration only significantly affected the experiments performed with DTPA-Fe, they were the major influence on the MPs removal efficiency decrease. In contrast, the presence of Ca 2+ and Mg 2+ only influence on this last one. Finally, the results of phytotoxicity disclosed the suitability of treated effluent to be reused in the agricultural sector. Conclusions: This work demonstrated that solar powered photo-Fenton catalysed by iron fertilizer EDDS is a suitable technology for depolluting water streams coming from pineapple processing plants at circumneutral pH, and its subsequent reuse for crop irrigation.

Iron-Marine Algal Interactions and Impacts: Decreasing Global Warming by Increasing Algal Biomass

Iron limitation in vast water bodies has been linked to decreased algal productivity, despite different iron-acquiring mechanisms, and the presence of ferritin in many algal species that act as an iron internal reservoir. Therefore, iron fertilization has been proposed to increase algal biomass and photosynthesis. This, in turn, will reduce carbon dioxide in the atmosphere and increase oxygen, thereby decreasing global warming, and achieving ecological balance. In addition, algal proliferation will hopefully lead to enhancement in biodiversity, Biological pump, fish productivity and, subsequently marine food industry. Many climate geoengineering experiments in the form of ocean iron fertilization have been conducted globally in order to achieve such a purpose. However, reservations remain as the outcomes are not as promising as were previously expected. As the temporal and spatial scales of iron fertilization experiments are limited, the effects on fish productivity remain speculative. On the other hand, side effects were also recorded. The main purpose of iron fertilization, for carbon dioxide sequestration and global warming mitigation, still remains to be fully realized and verified. Several improvements and future modifications are suggested, and legal issues are discussed in this review.

Features of the soybean photosynthetic productivity indicators formation depending on the foliar nutrition

The three-year research findings prove that foliar nutrition with trace elements influences the dynamics ofleaf surface formation, dry matter accumulation, and soybean photosynthetic net productivity under theWestern Forest-Steppe conditions of Ukraine. It was found out that foliar nutrition with the particular traceelements could enlarge the soybean leaf surface area, chlorophyll content and dry matter yield. During theexperimental studies, a positive effect on increasing the leaf surface area in soybean crops during the end offlowering was found in the variants where copper, iron and molybdenum-containing fertilizer were applied.The leaf surface area in the variant where copper was applied reached 46.3 thousand m-2 ha, which confirmsthe importance of copper in the formation of sugars and protein, direct participation in the process ofphotosynthesis. On the basis of the conducted researches it is established that in general on the amount ofchlorophyll in soybean leaves foliar feeding has a significant effect. The average chlorophyll content insoybean leaves was 1.10 mg-2 g of raw weight. The dynamics of dry matter by phases of growth anddevelopment of soybeans is established. Soybean produced the maximum amount of dry matter duringgrain ripening. Thus, 7.59 t-1 ha of dry matter was formed during the control.

Rice growth improvement, bio-fortification, and mitigation of macronutrient requirements through foliar application of zinc and iron- glycine chelate and zinc sulfate

Foliar application of Zinc (Zn) and Iron (Fe) fertilizers is known to be an effective solution to enhance rice grain yield and bio-fortification. The objectives of the current field experiment were to evaluate the effects of the foliar application of 0.5, 1, and 1.5 kg ha−1 of Zn and Fe glycine amino acid chelates and ZnSO4 on rice grain yield, protein, Zn, and Fe content of head rice (Hashemi cultivar) under both in the recommended and ½ of the recommended dose of NPK. The highest increase in the grain yield was recorded at 0.5 kgha−1 Fe-glycine amino acid chelate by about 29.2%. The maximum increase in protein and Zn content of head rice were recorded at 1.5 kg ha−1 of glycine amino acid-Zn chelate by about 10.5 and 22.3%, respectively. The most effective treatment to enhance the Fe content of head rice was the foliar application of 1.5 kg ha−1 of glycine amino acid-Fe chelate by about 32.6%. Interestingly, the foliar application of 1 kg ha−1 Zn-glycine amino acid chelate plus 1 kg ha−1 Fe-glycine amino acid chelate at the plots that received ½ of recommended NPK increased the grain yield, and protein, Zn and Fe content of head rice compared to control by about 7%, 18.5, 7.5, and 26.2, respectively. Therefore, regardless of rates and types, foliar application of Zn and/or Fe could enhance both rice yield, protein, Zn, and Fe content of head rice both in plots that received recommended and ½ of the recommended dose of NPK.

Integrated Zinc and Iron Management Practices for Enhancing Productivity and Flower Quality of Marigold

An experiment was conducted at the Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, Coimbatore during 2021-2022 to evaluate the effect of zinc and iron on growth, quality, yield and biochemical trait of marigold cv. Local Orange. The experiment was laid out in completely randomized design (CRD) with eight treatments and three replications. The eight treatments included an untreated control (T1) , 100% RDF (T2) , along with RDF soil application of FYM enriched ZnSO4 and FeSO4 @ 10 and 15 kg ha-1 respectively (T3), along with RDF soil application of FYM enriched ZnSO4 and FeSO4 @ 15 and 20 kg ha-1 respectively (T4), along with RDF soil application of FYM enriched ZnSO4 and FeSO4 @ 20 and 25 kg ha-1 respectively (T5), along with RDF foliar spray of ZnSO4 and FeSO4 each @ 0.5% (T6), along with RDF foliar spray of ZnSO4 and FeSO4 @ 0.5 and 1.0 % respectively (T7) , along with RDF foliar spray of 1.0 % liquid multi micronutrient (T8). The effect was assessed on growth, quality, yield and xanthophyll content in marigold flower. The results revealed that foliar application of ZnSO4 and FeSO4 each @ 0.5 % along with RDF at 20DAT and 35DAT recorded maximum plant growth, flower quality and flower yield. On xanthophyll content foliar application of 1.0 % liquid multi micronutrient along with RDF produced significant effect compared to control. The present study revealed that the integrated application of zinc and iron fertilizer significantly improved the growth, yield, quality of marigold crop. However both soil application and foliar spray of zinc and iron showing significant effect compared to control for better productivity and flower quality of marigold.

Complete Genome Sequence of Vibrio maritimus BH16, a Siderophore-Producing Mutualistic Bacterium Isolated from Diatom Skeletonema costatum.

Complete Genome Sequence of Vibrio maritimus BH16, a Siderophore-Producing Mutualistic Bacterium Isolated from Diatom Skeletonema costatum.

Effect of Adding Bio-Fertilizer and Spraying Nano - and Chelated Iron Fertilizer on the Nutrient Content of Orange Seedling Leaves

The study was carried out in the certified citrus propagation nursery of the Horticultural and Forestry Company in Al-Hindiya District / Holy Karbala Governorate during the period 20/4/ up to 20/8/2021, in order to study the effect of adding bio-fertilizer and spraying nano and chelated iron fertilizers on the content of orange seedlings leaves of the elements food. The experiment included three factors, the first biological fertilizing factor, adding ground at four levels, which are (the comparison treatment, azotobacter, mycorrhizal fungi, mycorrhizal fungi + azotobacter). It is the spraying of chelated iron in three levels (zero, 3, and 6 g / liter). A factorial experiment was carried out with a Randomized Complete Block Design, and the averages of traits were compared with the L.S.D. test at the 5% probability level. The results indicated: The biofertilization treatment (Mycorrhizal fungus+ Azotobacter bacteria). And the spraying treatment with nano iron fertilizer (3 g. L-1) was significantly superior in the content of orange seedlings leaves of nutrients (Zn,Fe,K,P,N) and the spraying treatment was The chelated iron fertilizer (6g.l-1) showed the same behavior and showed significant differences in the content of nutrients in the leaves. It gave the highest concentrations of the studied elements. The dual interactions between the study factors gave significant differences in the school characteristics, as it gave the treatment (Azotobacter + Mycorrhizae) + spraying of nano iron (3 g. L-1), and biological fertilization (Azotobacter + Mycorrhizae) + spraying of chelated iron (6 g. L-1), And (nano iron spray (3 g.l-1) + chelated iron spray (6g.l-1) the highest values are superior to the rest of the treatments and reached (2.58%, 0.68%, 2.81%, 300.79 mg. kg-1. dry weight, 42.80 mg. kg-1.d.w.) (2.55%, 0.64%, 2.97%, 297.79 mg. kg-1. d.w., 42.19 mg. kg-1. d.w.) (2.49%, 0.62%, 2.74%, 256.17 mg kg-1 dry weight, 39.66 mg kg-1 dry weight, respectively, gave the triple interaction treatment (Azotobacter + Mycorrhizae) + spray of nano iron (3 g. L-1) + spray of chelated iron (6 g). L-1) was significantly superior in leaf content of the studied elements, and it reached (2.77%, 0.75%, 3.20%, 309.17 mg. kg-1. dry weight, 49.40 mg. kg-1. dry weight), respectively.

Low source-inherited iron solubility limits fertilization potential of South American dust

Where atmospheric processing is weak due to low anthropogenic emissions, fertilization of iron-limited oceans by non-volcanic mineral dust aerosols strongly depends on iron solubility at the sources. Southern South America (SSA) is a pristine environment and the main dust supplier to the southern oceans, the most sensitive to iron fertilization. Thus, the present-day lack of SSA dust fertilization of the southern oceans is hypothesized to reflect low source-inherited iron bioavailability. However, a dearth of geochemical studies on SSA dust prevents testing this hypothesis. To remedy this, we conducted the first systematic sampling of SSA dust sources. Iron leaching experiments showed fractional solubilities of close-to-source dust (bulk) and dust-emitting surface sediments (<63 µm) in pure water (0.05 ± 0.05%), seawater (0.03 ± 0.04%) and 1% nitric acid (5 ± 6%) that imply a low mass-normalized fertilization potential of SSA dust compared to dust from other regions. Based on grain size, size-resolved mineralogy, elemental chemistry and iron speciation determinations, we found that variability in labile iron is enhanced by high clay contents, small grain size and higher proportions of paramagnetic versus non-paramagnetic iron, irrespective of oxidation state. The independence of the most labile, water-soluble iron on grain size and its strong negative correlation to the Chemical Index of Alteration may imply that we currently underestimate the role of coarse glaciogenic dust as a supplier of bioavailable iron during drier-than-present ice ages when continental chemical weathering was reduced, and during which enhanced supply of dust-borne bioavailable iron to the southern oceans is observed.

Southern Ocean Phytoplankton Stimulated by Wildfire Emissions and Sustained by Iron Recycling

AbstractLarge ash plumes emitted by the 2019–2020 Australian wildfires were associated with a widespread phytoplankton bloom in the iron‐limited Pacific sector of the Southern Ocean. In this study, we used satellite observations and aerosol reanalysis products to study the regional phytoplankton community response to wildfire emissions. The bloom was stimulated by pyrogenic iron fertilization and coincided with elevated cellular pigment concentrations, increased photochemical efficiency, and apparent community structural shifts. Physiological anomalies were consistent with previously observed phytoplankton responses to iron stress relief and persisted for up to 9 months. Supported by a regional iron budget, we conclude that the bloom was sustained by iron recycling and episodic inputs of pyrogenic and dust‐borne mineral iron. The continuous regeneration of iron was likely facilitated by the bloom's large size, mitigating edge dilution effects, as well as enhanced bioavailability of pyrogenic and mineral iron due to atmospheric and chemical processing during long‐range transport.

Fortification of Organic Manures with Iron on Nutrient Release Characteristics

Aims: The objective of current study was to examine the nutrient release pattern by enriching different organic manures with iron fertilizer at different ratios in regular sampling intervals.&#x0D; Study Design: The design used in this current study was Factorial completely randomized block design with six treatments replicated thrice.&#x0D; Place and Duration of Study: An incubation experiment was carried out in the Department of Soil Science and Agricultural Chemistry, Tamil Nadu Agricultural University, India during December - March 2022.&#x0D; Methodology: An incubation experiment was carried out by enriching inorganic iron fertilizer with three different organics such as FYM, vermicompost and biocompost in two ratios viz., 1:5 and 1:10 at four different sampling intervals 7, 14, 21 and 28 days after incubation and analyzed for various physical and chemical properties to study the iron release pattern.&#x0D; Results: The results revealed that the iron content ranged from 5324 to 8823 mg kg-1. Among all the combinations, the highest nutrient release was found in FeSo4 enriched with vermicompost 1:10 ratio at 21 DAI which is followed by FeSo4 enriched with FYM 1:10 ratio.&#x0D; Conclusion: The present study revealed that the integrated application of organic and inorganic fertilizer significantly improved the iron use efficiency. Only a few work were reported on integrated application of micronutrient at different organic fertilizer rates, however need further studies to validate the reliability.

Performance of Annona Plants Subjected to Different Graft Combinations, Soil Types and Iron Fertilization

In the last decade, annona crop was introduced to Lebanon. This experiment was conducted to enhance the adaptation of annona to local conditions. Three scion/rootstock combinations were obtained from self– and cross– cleft grafting of Annona squamosa (Sq) and Annona cherimola (Ch), planted in calcareous “white soil” and clay–loamy “red soil”, and fertilized or not by iron (Fe) through fertigation. In the third year, the treatment red soil–iron fertilization–Sq/Ch had significantly highest plant height, trunk diameter, leaf number, number of primary roots, fruit number and yield. In the third year, despite iron fertilization, plants of the three graft combinations cultivated in red soil had higher flower number, fruit number, individual fruits weight and yield, than those planted in white soil. In the same year, iron fertilization in white soil had only affected total dry mass, leaf mass fraction and leaf iron content. However, iron fertilization of Sq/Ch planted in red soil has improved leaf number, primary root number, primary root length, leaf chlorophyll index, and leaf iron content compared to non–fertilized plants. Conclusively, iron fertilization in red soil could be a useful method improving the performance and yielding capacity of annona crop mainly in Sq/Ch combination.

Effect of different concentrations of foliar iron fertilizer on chlorophyll fluorescence characteristics of iron-deficient rice seedlings under saline sodic conditions

The effectiveness of iron is reduced in saline conditions, which can easily lead to iron deficiency and inhibit photosynthesis in rice. In this study, 4-week-old Fe-deficient rice seedlings were treated under saline sodic stress (50 mM) to different concentrations (0, 0.2%, 0.4%, 0.8%, 1.6%, and 3.2%) of foliar iron fertilizer (FeEDDHA). Differences in prompting fluorescence and the MR820 signal of rice leaves after 7 days of treatment were probed using the JIP-test. The results show that the performances of the two rice varieties were in general agreement. Under iron deficiency and soda salinity stress conditions, rice growth was inhibited, and the pigment content, specific energy flux, quantum yield, performance of the active PSII reaction center (PIABS) and the oxidation (Vox) and reduction rates (Vred) of PSI were reduced. These indicators first increase and then decrease with increasing iron fertiliser concentrations. The best results were obtained with the Fe3 treatment (0.8%). Fluorescence parameters such as the relative variable fluorescence (WK and VJ) and the quantum yield of energy dissipation (φDo) showed opposite trends. This suggests that iron deficiency/excess and soda saline stress disrupt the electron and energy transport in the photosystem. Appropriate iron fertilization concentration can repair the photosynthetic electron transport chain, improve electron transport efficiency and promote balanced energy distribution. Therefore, we suggest that moderate amounts of Fe are beneficial for improving the electron and energy transport properties of the photosystem, while spraying high concentrations of Fe fertilizer has a negative effect on improving salt tolerance in rice.

Dust correlation and oxygen isotope stratigraphy in the Southern Ocean over the last 450 kyrs: An Indian sector perspective

The chronology of Southern Ocean (SO) marine sediment cores forms the basis of understanding the SO paleoceanography, with significant implications for global climate. Because tuning of the oxygen isotope (δ18O) record of a marine sediment core to a δ18O stack (δ18O stratigraphy) is difficult in the SO because of a general paucity of calcareous foraminifera, tuning of the dust proxy signal of a marine sediment core to the dust record of an ice core (dust correlation) is a promising way to construct an age–depth model. However, the reliability of dust correlation has not been established, especially beyond the last ∼300 kyrs, and such work has been performed more in the Atlantic and Pacific sectors of the SO than in the Indian sector. Here we present a new dust correlation using the rock magnetic record, together with continuous δ18O stratigraphy, for a marine sediment core in the Indian sector of the SO over the last ∼410 kyrs. The δ18O stratigraphy is consistent with the dust correlation within their chronological uncertainties, supporting the reliability of the latter chronology for glacial–interglacial timescales. However, the dust correlation often produces older ages than the δ18O stratigraphy by up to 3 kyrs (410–126 ka and 84–50 ka). We additionally compiled, based on dust correlation, available dust proxy records in the circum-Antarctic SO for the last 450 kyrs to discuss variations in the dust proxy record within the Indian sector and between all three sectors. For the Indian sector, there is a marked difference in dust proxy signals for Marine Isotope Stage (MIS) 6 between two cores that have markedly different latitudinal positions relative to the oceanic fronts. Increased biogenic magnetite production by iron fertilization in the Subantarctic Zone during MIS 6 may partly explain the difference between the two cores. For the circum-Antarctic SO, moving correlation coefficients were computed between the marine sediment-core dust proxy signals and the dust flux of an Antarctic ice core. Strong correlation was recognized for intervals of high dust flux in the ice core, except for MIS 6. Although minor, the slightly lower correlation in the Indian sector than in the other sectors indicates a contribution from local dust source and volcanic materials and thus suggests the necessity for caution when performing dust correlation in the Indian sector of the SO.

Changes in flower yield, essential oil yield and oil composition after soil and foliage zinc and iron fertilization in German chamomile

In order to analyze the effects of zinc (Zn) and iron (Fe) on growth, yield, oil production and oil quality of German chamomile, an open field experiment was conducted at the Research Center, CSIR-Central Institute of Medicinal and Aromatic Plants (CIMAP), Pantnagar, Uttarakhand, India in 2019–2020 and 2020–2021. The experiment was set according to Randomized block design (RBD) with 7 treatments and three replications. Treatments were as follow: T1: control (without Zn or Fe fertilizers), T2: Foliar Fe spray @ 0.5%, T3: Foliar Fe spray @ 1.0%, T4: Foliar Zn spray @ 0.5%, T5: Foliar Zn spray @ 1.0%, T6: Mixing of Zn in soil @ 30 kg/ha before transplanting, T7: Mixing of Fe in soil @ 30 kg/ha before transplanting. Foliar spray of zinc (Zn) and iron (Fe) was conducted twice before flowering throughout the crop growth period. Obtained results showed that the plant height, canopy, number of flowers, fresh & dry flower yield, oil production, oil content and oil composition were radically increased and improved by foliar spray and soil mixing of Zn and Fe, compared to control. The maximum fresh flower & dry flower yield, oil content, and oil production were recorded in the treatment of foliar spray of Zn @ 0.5% followed by 1.0% in 2019–2020 and 2020–2021. The results also showed that Zn and Fe improved the oil quality and increased the concentration of major compounds like chamazulene, Z-spiroether, α-bisabolol oxide-A & B in oil compared with control.

Biogeochemical Equilibrium Responses to Maximal Productivity in High Nutrient Low Chlorophyll Regions

AbstractWhether ocean iron fertilization in high nutrient low chlorophyll (HNLC) regions is a practical geoengineering strategy to combat climate warming has been debated because the fate of absorbed carbon by the ocean remains unclear. We use an optimized oceanic biogeochemical inverse model to explore the equilibrium responses to increased productivity in major HNLC regions. We find that an overall downward shift of nutrients and carbon from the surface and intermediate to the deep waters with maximal productivity in the HNLC Southern Ocean (SO), North Pacific (NP) and eastern equatorial Pacific (EP). The efficiency of soft tissue pump is increased by 37.8%, 2.7% and 5.4% in the SO, EP and NP simulation while atmospheric CO2 concentration is drawn down by 45.1, 3.4 and 6.7 ppm, respectively. Meanwhile, global mean oxygen is decreased by 21.1%, 1.3% and 2.4% in the SO, EP and NP simulation, accompanied by an expansion of oxygen minimum zones by 400%, 26% and 63%, respectively. Our study indicates that iron fertilization has the potential to be an effective geoengineering approach to mitigate climate warming but also has a strong impact on the development of ocean hypoxia.

Antiphased dust deposition and productivity in the Antarctic Zone over 1.5 million years

The Southern Ocean paleoceanography provides key insights into how iron fertilization and oceanic productivity developed through Pleistocene ice-ages and their role in influencing the carbon cycle. We report a high-resolution record of dust deposition and ocean productivity for the Antarctic Zone, close to the main dust source, Patagonia. Our deep-ocean records cover the last 1.5 Ma, thus doubling that from Antarctic ice-cores. We find a 5 to 15-fold increase in dust deposition during glacials and a 2 to 5-fold increase in biogenic silica deposition, reflecting higher ocean productivity during interglacials. This antiphasing persisted throughout the last 25 glacial cycles. Dust deposition became more pronounced across the Mid-Pleistocene Transition (MPT) in the Southern Hemisphere, with an abrupt shift suggesting more severe glaciations since ~0.9 Ma. Productivity was intermediate pre-MPT, lowest during the MPT and highest since 0.4 Ma. Generally, glacials experienced extended sea-ice cover, reduced bottom-water export and Weddell Gyre dynamics, which helped lower atmospheric CO2 levels.

Mineral-enhanced biological pump&amp;mdash;A strategy based on mineral-microbe interactions for increasing carbon sink in water

<p indent=0mm>Addressing the threats posed by global climate change by reducing the number of greenhouse gases is currently one of the most important research goals of the scientific community. Ocean iron fertilization (OIF) is a geoengineering strategy aimed at mitigating global warming through human intervention. The OIF concept is based on the idea that artificial adding of iron nutrients into iron-depleted regions of the ocean will lead to a rapid boost of phytoplankton populations and the mass sinking of organic matter that ultimately leads to the sequestration of significant amounts of atmospheric CO₂ in the deep sea and sediments. The OIF experiments have been conducted in past over the time and the space scales of weeks and kilometres in polar, subpolar and tropical areas of the oceans. The results have generated new knowledge and a better understanding of the role of iron in regulating marine ecosystems and have confirmed that the iron supply is one of the key controls on the dynamics of phytoplankton blooms, such as diatom as the base of the marine food chain, which in turn affect the whole biogeochemical cycling of carbon. However, the OIF as an effective carbon control strategy is not adequately supported with concerns about potential significant impacts on marine ecosystems. The iron fertilization also did not significantly strengthen the vertical carbon export to the deep sea and thereby the sequestration of CO₂. The efficacy by which the OIF vertically exports organic carbon associated with diatom blooms to the deep sea remains constrained due to the remineralization and the loss of organic carbon during the sinking process of diatomaceous biogenic silica (BSi). Therefore, to address these limitations, the next generation of the IOF geoengineering experiments should be designed to improve the low efficiency of the vertical export of bloomed phytoplankton, which will reduce the loss of organic carbon during the sinking of biomass. In our recent studies, we observed a noticeable dissolution-inhibition effect of Al-bearing lake diatomaceous BSi, which is caused by the high content of Al incorporation in the structure of the BSi. This finding inspired a new idea about the possibility of incorporating naturally occurring, environmentally safe and Al-rich minerals as an Al source for the geoengineering experiments. We hypothesize that clay minerals, with characteristically high contents of Al and Si, might be good ingredients for mineral fertilization in geoengineering experiments to enhance the efficiency of the vertical carbon export of the biological pump. This new proposed mineral-aided process is termed mineral-enhanced biological pump (MeBP). In this paper, the concept, background and theoretical basis of MeBP for CO₂ sequestration in water bodies as a new and inexpensive geoengineering strategy are explained. The basic idea of the MeBP concept is to use finely grained powders of minerals, such as clay minerals as nutrients for geoengineering or ecological engineering experiment to enhance the efficiency of the complexes of microbial organic matter and minerals and to hinder the loss of particulate organic carbon by adjusting the mineral ratios and regulating the particle properties. If so, the improved carbon sequestration efficiency of the biological pump and the CO₂ sink enhancement in water bodies could be achieved. The MeBP offers several potential advantages such as application simplicity, low-cost, scalability, environmental friendliness, and flexibility, and it could be applied alone or in combination with other carbon sequestration strategies. Also, the approaches for the research and application of MeBP, the environmental and ecological risks of applying MeBP and the possible ways of avoiding these risks are discussed. These discussions aim to stimulate new thinking toward the development of new technologies of increasing carbon sink in water bodies that are sustainable, ecologically acceptable and scalable, and can be translated into real applications and engineering practices.