Micronutrient Fertilizers

Shuman, L. M.

doi:10.1300/j144v01n02_07

Cited by 67 publications

(45 citation statements)

References 93 publications

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“…Mineral elements can be present in the soil as free ions, or ions adsorbed onto mineral or organic surfaces, as dissolved compounds or precipitates, as part of lattice structures or contained within the soil biota. The most important soil properties governing mineral availability are soil pH, redox conditions, cation exchange capacity, activity of microbes, soil structure, organic matter and water content (Shuman, 1998; Frossard et al ., 2000). Indeed, although high concentrations of Fe, Zn and Cu occur in many soils, the phytoavailability of these mineral elements is often restricted by soil properties (see References S4), which predetermine both genetic and agricultural strategies for their effective utilization.…”

Section: Phytoavailability Of Mineral Elementsmentioning

confidence: 99%

“…In nonpolluted areas, typical Zn 2+ concentrations in the soil solution range from 10 −8 to 10 −6 M and Cu 2+ concentrations range from 10 −9 to 10 −6 M (Barber, 1995; Welch, 1995; Frossard et al ., 2000; Broadley et al ., 2007). Because of their low concentrations in the soil solution and small diffusion coefficients, Zn 2+ and Cu 2+ have limited mobility in the soil (Gupta, 1979; Barber, 1995; Shuman, 1998; Whiting et al ., 2003; Broadley et al ., 2007; Cakmak, 2008) and plant roots must forage through the soil to acquire sufficient Zn and Cu for plant nutrition (Rengel, 2001; Hacisalihoglu & Kochian, 2003). Processes that increase Fe, Zn and Cu phytoavailability in the rhizosphere, such as the exudation of protons, phytosiderophores and organic acids by roots, generally increase the concentrations of these elements in crops (Welch, 1995; Rengel, 2001; Abadía et al ., 2002; Hoffland et al ., 2006; Wissuwa et al ., 2006; Ismail et al ., 2007; Degryse et al ., 2008).…”

Section: Phytoavailability Of Mineral Elementsmentioning

confidence: 99%

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Biofortification of crops with seven mineral elements often lacking in human diets – iron, zinc, copper, calcium, magnesium, selenium and iodine

White¹,

2009

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SummaryThe diets of over two-thirds of the world's population lack one or more essential mineral elements. This can be remedied through dietary diversification, mineral supplementation, food fortification, or increasing the concentrations and/or bioavailability of mineral elements in produce (biofortification). This article reviews aspects of soil science, plant physiology and genetics underpinning crop biofortification strategies, as well as agronomic and genetic approaches currently taken to biofortify food crops with the mineral elements most commonly lacking in human diets: iron (Fe), zinc (Zn), copper (Cu), calcium (Ca), magnesium (Mg), iodine (I) and selenium (Se). Two complementary approaches have been successfully adopted to increase the concentrations of bioavailable mineral elements in food crops. First, agronomic approaches optimizing the application of mineral fertilizers and/or improving the solubilization and mobilization of mineral elements in the soil have been implemented. Secondly, crops have been developed with: increased abilities to acquire mineral elements and accumulate them in edible tissues; increased concentrations of 'promoter' substances, such as ascorbate, β-carotene and cysteine-rich polypeptides which stimulate the absorption of essential mineral elements by the gut; and reduced concentrations of 'antinutrients', such as oxalate, polyphenolics or phytate, which interfere with their absorption. These approaches are addressing mineral malnutrition in humans globally.

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Section: Phytoavailability Of Mineral Elementsmentioning

confidence: 99%

Section: Phytoavailability Of Mineral Elementsmentioning

confidence: 99%

Biofortification of crops with seven mineral elements often lacking in human diets – iron, zinc, copper, calcium, magnesium, selenium and iodine

White¹,

2009

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“…Zinc is usually added to soil as an inorganic fertilizer (Rengel, 2002b;Rehman et al, 2012;Singh et al, 2014 and synthetic chelates (with EDTA, 14% Zn; with HEDTA and NTA, 9% Zn) (Shuman, 1998).…”

Section: Zincmentioning

confidence: 99%

Availability of Mn, Zn and Fe in the rhizosphere

Rengel

2015

J. Soil Sci. Plant Nutr.

214

186

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This review paper critically assesses the literature on soil-microbe-plant interactions influencing availability of micronutrients in the rhizosphere. The emphasis is placed on Zn and Mn, but Fe is also covered to some extent.Micronutrient availability in the rhizosphere is controlled by soil and plant properties, and interactions of roots with microorganisms and the surrounding soil. Plants exude a variety of organic compounds (carboxylate anions, phenolics, carbohydrates, amino acids, enzymes, etc.) and inorganic ions (protons, phosphate, etc.) to change chemistry and biology of the rhizosphere and increase micronutrient availability. Increased availability may result from solubilization and mobilization by short-chain organic acid anions, amino acids and other low-molecular-weight organic compounds. Acidification of the rhizosphere soil increases mobilization of micronutrients (eg. for Zn, 100-fold increase in solubility for each unit of pH decrease).For diffusion-supplied micronutrients, the uptake rate is governed by the soil nutrient supply. Fertilisation with micronutrients (more so in case of Zn than Fe) can be effective in increasing the concentration of micronutrients at the soil-root interface. In addition, micronutrient-efficient crops and genotypes can increase an available nutrient fraction and hence increase micronutrient uptake.Our understanding of the physiological processes governing exudation and the soil-plant-microbe interactions in the rhizosphere is currently inadequate, especially in terms of spatial and temporal variability in root exudation as well as the fate and effectiveness of organic and inorganic compounds in increasing availability of soil micronutrients and undesirable trace elements. The interactions between microorganisms and plants at the soilroot interface are particularly important as well obscure.

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“…Phosphorus (P) fertilizer efficiency in agricultural systems is low, with only 10-20 % of fertilizer applied P used by crops in the year of application, and residual value rarely exceeding 50 % (Bolland and Gilkes 1998). Typically, fertilizer P is converted to less soluble forms due to reactions with aluminium (Al) and/or iron (Fe) in acid soils and calcium (Ca) in neutral to alkaline soils (Holford 1997).…”

Section: Introductionmentioning

confidence: 99%

Wheat, canola and grain legume access to soil phosphorus fractions differs in soils with contrasting phosphorus dynamics

2009

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Despite the high phosphorus (P) mobilizing capacity of many legumes, recent studies have found that, at least in calcareous soils, wheat is also able to access insoluble P fractions through yet unknown mechanism(s). We hypothesized that insoluble P fractions may be more available to non-legume plants in alkaline soils due to increased dissolution of the dominant calcium(Ca)-P pool into depleted labile P pools, whereas non-legumes may have limited access to insoluble P fractions in iron(Fe)-and aluminium (Al)-P dominated acid soils. Four crop species (faba bean, chickpea, wheat and canola) were grown on two acid and one alkaline soil under glasshouse conditions to examine rhizosphere processes and soil P fractions accessed. While all species generally depleted the H 2 O-soluble inorganic P (water Pi) pool in all soils, there was no net depletion of the labile NaHCO 3 -extractable inorganic P fraction (NaHCO 3 Pi) by any species in any soil. The NaOH-extractable P fraction (NaOH Pi) in the alkaline soil was the only non-labile Pi fraction depleted by all crops (particularly canola), possibly due to increases in rhizosphere pH. Chickpea mobilized the insoluble HCl Pi and residual P fractions; however, rhizosphere pH and carboxylate exudation could not fully explain all of the observed Pi depletion in each soil. All organic P fractions appeared highly recalcitrant, with the exception of some depletion of the NaHCO 3 Po fraction by faba bean in the acid soils. Chickpea and faba bean did not show a higher capacity than wheat or canola to mobilize insoluble P pools across all soil types, and the availability of various P fractions to legume and non-legume crops differed in soils with contrasting P dynamics.

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Micronutrient Fertilizers

Cited by 67 publications

References 93 publications

Biofortification of crops with seven mineral elements often lacking in human diets – iron, zinc, copper, calcium, magnesium, selenium and iodine

Biofortification of crops with seven mineral elements often lacking in human diets – iron, zinc, copper, calcium, magnesium, selenium and iodine

Availability of Mn, Zn and Fe in the rhizosphere

Wheat, canola and grain legume access to soil phosphorus fractions differs in soils with contrasting phosphorus dynamics

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