Micronutrients sources

Secondary and Micronutrients in Fertilizers The great majority of farm fertilizers are produced, marketed, and appHed with regard only to the primary plant nutrient content. The natural supply of secondary and micronutrients in the majority of soils is usually sufficient for optimum growth of most principal crops. There are, however, many identified geographical areas and crop—soil combinations for which soil appHcation of secondary and/or micronutrient sources is beneficial or even essential. The fertilizer industry accepts the responsibiHty for providing these secondary and micronutrients, most often as an additive or adjunct to primary nutrient fertilizers. However, the source chemicals used to provide the secondary and micronutrient elements are usually procured from outside the fertilizer industry, for example from mineral processors. The responsibiHties of the fertilizer producer include procurement of an acceptable source material and incorporation in a manner that does not decrease the chemical or physical acceptabiHty of the fertilizer product and provides uniform appHcation of the added elements on the field. 

Generally, soluble materials are more effective as micronutrient sources than are insoluble ones. For this reason, many soil minerals that contain the micronutrient elements are ineffective sources for plants. Some principal micronutrient sources and uses are summarized below. In this discussion the term frits refers to a fused, pulverized siUceous material manufactured and marketed commercially for incorporation in fertilizers. Chelates refers to metaHoorganic complexes specially prepared and marketed as especially soluble, highly assimilable sources of micronutrient elements (see CHELATING agents). 

Since micronutrient fertilizers must be applied at very low rates to avoid plant toxicity, the prevailing practice is to incorporate them with macronutrient fertilizers. This can be accomplished by incorporation with solid fertilizers during the manufacturing process, by bulk blending with granular fertilizers, or by mixing with fluid fertilizers just prior to application. Care must be taken to select micronutrient sources and macronutrient fertilizers that are compatible to avoid the formation of reaction products that reduce availability of nutrients to plants (Mortvedt and Cunningham, 1971). 

Micronutrient sources vary considerably in their physical state, chemical reactiwty, cost, and availabi ty to plants [12]. There are four main classes of micronutri-... 

Methods of micronutrient application include application directly to soil, in foliar sprays, and as seed treatment. The most common application method for crops is soil application [12]. Because recommended application rates usually are less than 10 kg/ha (on an elemental basis), it is difficult to achieve uniformity when individual micronutrient sources are applied separately in the field. Therefore, both granular and fluid fertilizers are commonly used as carriers of micronutrients. Including micronutrients with mixed fertilizers is a convenient method of application, and it allows a more uniform distribution with conventional application equipment. 

It should be recognized that when micrcnuhrient materials are mixed with other fertilizers, chemical reactions are likely to occur. Lehr [14] has described many of the numerous chemical reactions. The effect of these chemical reactions may or may not be important. A water-soluble micronutrient source may be partially or wholly converted to a water-insoluble compourxl. Conversely, water-insoluble sources may be converted to water-soluble forms. The gain or loss of water solubility may or may not be important. Some examples follow. 

Both AIPO4 and BPO4 can be used as refractory materials, and the latter has found application as a versatile catalyst, as a micronutrient source of boron in fertiliser technology and as a reagent for the preparation of lanthanide and actinide phosphates (5.75, 5.76) or pyrophosphates (5.109), (5.110). Iron phosphate (qnartz form) can also be prepared (5.74) [35]. 

Iron. As with copper, some dozen or more materials are used as fertilizer Hon sources. These include ferrous and ferric oxides and sulfides and ferrous ammonium phosphate [10101 -60-7] ferrous ammonium sulfate [10045-89-3] frits, and chelates. In many instances, organic chelates are more effective than inorganic materials. Recommended appHcation rates range widely according to both type of micronutrient used and crop. Quantities of Fe range from as low as 0.5 kg/hm as chelates for vegetables to as much as a few hundred kg/hm as ferrous sulfate for some grains. 

Further efficient fermentative methods for manufacture of riboflavin have been patented one is culturing C. famata by restricting the carbon source uptake rate, thereby restricting growth in a linear manner by restriction of a micronutrient. By this method, productivity was increased to >0.17 g riboflavin/L/h (63). The other method, using Bacillus subtilis AJ 12644 low in guanosine monophosphate hydrolase activity, yielded cmde riboflavin 0.9 g/ L/3 days, when cultured in a medium including soy protein, salts, and amino acids (64). 

PN should provide a balanced nutritional intake, including macronutrients, micronutrients, and fluid. Macronutrients, including amino acids, dextrose, and intravenous lipid emulsions, are important sources of structural and energy-yielding substrates. A balanced PN formulation includes 10% to 20% of total daily calories from amino acids, 50% to 60% of total daily calories from dextrose, and 20% to 30% of total daily calories from intravenous lipid emulsion. Micronutrients, including electrolytes, vitamins, and trace elements, are required to support essential biochemical reactions. Parenteral... 

Fruits and vegetables have historically been considered rich sources of some essential dietary micronutrients and fibers, and more recently they have been recognized as important sources for a wide array of phytochemicals that individually, or in combination, may benefit health (Stavric 1994 Rechkemmer 2001). Therefore, some people have conferred on fruits and vegetables the status of functional foods. There are many biologically plausible reasons for this potentially protective association, including the fact that many of the phytochemicals act as antioxidants. 

Media were devised that supported consistent growth of the rhizobia, and mannitol often was favored as the energy source in the media. Yeast extract commonly was added to supply micronutrients. Selection of effective strains of the rhizobia was an empirical process based on greenhouse and field testing. Usually, several effective strains were grown on liquid media and then mixed on a solid support for distribution. 

The data presented in Table 11.1 indicate that the fluvial gross river flux is the major source of trace metals to the oceans and that most of this flux is in particulate form (fluvial gross particulate flux). But the majority of this particulate flux is trapped within estuaries, primarily via settling, and, hence, is not released into the open ocean. As a result, the fluvial net particulate flux is only about 10% of the fluvial gross particulate flux. In seawater, most of this particulate metal remains in solid form due to low solubilities. The particulate metals eventually settle to the seafloor and are subsequently buried in the sediments. In the case of iron, a small fraction of the particulate pool does dissolve. In the surface waters, solubilization of particulate iron can provide a significant amount of this micronutrient to the phytoplankton. 

Figure 6.28 The vascular link between the absorptive area of the intestine and the liver the hepatic portal vein. This vein is the only one that links capillaries in two organs and is fundamentally important in ensuring that the liver has access to all the nutrients, including the micronutrients, absorbed by the intestine. Note that the liver has two sources of blood.

Dietary Reference Intake (DRI) of Cu, 17-18% of the DRI of K, P, and Fe, and between 5 and 13% of the DRI of Zn, Mg, and Mn (Table 5.1). Potatoes are generally not rich in Ca, but can be a valuable source of trace elements, such as Se and I, if fertilized appropriately (Eurola et al., 1989 Poggi et al., 2000 Turakainen et al., 2004 Broadley et al., 2006). Moreover, since potato tubers have relatively high concentrations of organic compounds that stimulate the absorption of mineral micronutrients by humans, such as ascorbate (vitamin C), protein cysteine and various organic and amino acids (USDA, 2006), and low concentrations of compounds that limit their absorption, such as phytate (0.11-0.27% dry matter Frossard et al., 2000 Phillippy et al., 2004) and oxalate (0.03% dry matter Bushway et al., 1984), the bioavailability of mineral elements in potatoes is potentially high. 

Andre, C. M., Ghislain, M., Bertin, P., Oufir, M., Herrera Mdel, R., Hoffmann, L., Hausman, J. R, Larondelle, Y, Evers, D. (2007a). Andean potato cultivars (Solanum tuberosum L.) as a source of antioxidant and mineral micronutrients. J. Agric. Food Chem., 55, 366-378. 

Iron, an important plant micronutrient, is adsorbed rapidly onto particles and becomes unavailable for uptake by phytoplankton. The major source of iron to the ocean is in the form of atmospheric dust. Relatively little is known about the temporal variability of total iron in surface waters,... 

In conclusion, it appears that the uptake enhancement of macro- and micronutrients due to HS is a synergic sum of various effects exerted by these molecules at a rhizosphere level. Besides a direct source of nutrient subsequent their decomposition and apart from their chelating properties, HS interaction with plant root plasma membrane has been demonstrated in relation to its solubility, its surfactant-... 

Brewers yeast (S. cerevisiae) is permitted as a feed ingredient in organic diets. This by-product was used traditionally in poultry diets in the past as a source of AA and micronutrients (Bolton and Blair, 1974), a practice largely discontinued because of economics. Inactivated yeast should be used for animal feeding since live yeast may grow in the intestinal tract and compete for nutrients. This ingredient can be used only at low levels in poultry diets... 

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