Plant contents

Zn deficit Foothills of Turkmenistan and Zerafshan ranges, Uzbekistan and Tajikistan 1.5-2 times reducing Zn content in all Serozem sub-types. The plant content is < 7.5 ppm The reducing Zn content in blood (up to 1.8 ppm) and wool of sheep. Lowering activity of Zn-containing ferments. Endemic parakeratosis... 

The assessment of plant-available soil contents can frequently be achieved and validated by field experiments for nutritionally essential elements, and, for a few potentially toxic elements such as chromium, nickel and molybdenum, at the moderately elevated concentrations that can occur in agricultural situations. The validation of extraction methods, devised for agricultural and nutritional purposes, is much less easy to achieve when they are applied to heavy metals and other potentially toxic elements, especially at the higher concentrations obtained in industrially contaminated land. This is not surprising in view of the fact that for some heavy metals, for example lead, there is an effective root barrier, in many food crop plants, to their uptake and much of the metal enters plants not from the root but by deposition from the atmosphere on to leaves. In these circumstances little direct correlation would be expected between soil extractable contents and plant contents. For heavy metals and other potentially toxic elements, therefore, extraction methods are mainly of value for the assessment of the mobile and potentially mobile species rather than plant-available species. This assessment of mobile species contents may well, however, indicate the risk of plant availability in changing environmental conditions or changes in land use. 

The use of chemical extractants for the assessment or prediction of agricultural crop plant contents, plant growth or health and the estimation of the likelihood of plant or animal (consuming the fodder plant) deficiency or toxicity has been a major topic of study in agricultural laboratories for almost half a century, although... 

Most soils contain approximately 95% of their dry mass as mineral material and 5% as organic material. This chapter is largely concerned with the mineral material, and organic matter is discussed only so far as it influences the fate of the inorganic elements. The mineral material is derived from the break down of rocks. Embryonic soils are little more than a few millimetres of rock debris colonised by lichens while at the other extreme, in the tropics, tens of metres of weathered material may overlie unaltered rock. In all cases, however, the chemical nature of the soil will be influenced by the geochemical nature of the parent rock. In turn, plant contents tend to reflect soil contents, albeit indirectly. 

Recently, Chojnacka et al (2005) have reported an excellent linear relationship between available PTMs (As, Cd, Cr, Cu, Hg, Mn, Pb and Zn) content in polluted industrial soils, as extracted by 2% (w/v) ammonium citrate solution, and wheat plants content. For some elements of environmental concern, such as Pb, As, Cd, Hg and Cr, also the results obtained by 0.1 M NaN03, 0.5 M KN03 and 0.05 M CaCl2... 

When PTMs concentration is well in excess of normal soil content, extraction method validation, in terms of direct correlation between soil extractable contents and plant contents, is less easy to achieve. In these cases, it may be adequate to develop an operational estimate of the mobile and potentially mobile metal species rather than plant-available species. It is necessary to analyse metal partitioning between such fractions as exchangeable sites, organic matter and minerals of varying solubility. 

Safety Series No. 50-SG-G8 Licenses for Nuclear Power Plants Content, Format and Legal Considerations (1982). 

If the plant safety shutdown is not rapid enough and an overpressure situation develops, then the pressure relief system is activated. Pressure vessel design codes such as the ASME Boiler and Pressure Vessel Code require relief devices to be fitted on all pressure vessels (see Section 13.17). If the relief system has been properly designed and maintained, then in the event of an overpressure incident, the plant contents will be vented via relief valves or bursting disks into the relief system, where liquids are recovered for treatment and vapors are sent to flare stacks or discharged to the atmosphere if it is safe to do so. The pressure relief system should allow the plant to be relieved of any source of overpressure before damage to process equipment (leaks, bursting, or explosion) can occur. 

Whether the researcher wants to know the P concentration in the plant material, or some measure of total plant content of P per plot (i.e. will the data collected allow the required calculations to be made ). 

Fluorine is not an essential plant nutrient but is essential for animals. However, continuous ingestion by the animals of excessive amounts of F can lead to fluorosis, and sub optimal levels in the diet, can have an equally damaging effect. Therefore, plant content of F is of interest to livestock producers. 

Column 2 of Table 1.1 shows the ratio of plant content to soil content of important ions. The hydrogen, carbon, and oxygen ratios are omitted because these ions are not derived directly from soils. The ratios are crude indices of the relative availability of soil components to plants. Calcium, sulfur, nitrogen, and potassium in soils are more available than iron and manganese. One goal of soil chemistry is to explain why ions in soils vary widely in their degree of plant availability. 

Animals derive their essential elements from plants. The ability of plants to supply these elements to plants and animals depends on a combination of factors availability of the ions in the soil solution, plant selectivity at the soil solution/root interface, and ion translocation from root to plant top. The system is good but not perfect. The concentrations of essential elements are occasionally too high or too low for animals, because plants can tolerate a much wider range of elemental concentrations than can animals. Plant contents of iron, for example, tend to be lower than ideal for the human diet. Grazing animals in a few semiarid parts of North America may suffer from high selenium, in Australia from low cobalt, and formerly in Norway from low phosphorus availability because of unsatisfactory amounts in soils. The supply of essential elements by plants to animals is generally adequate cases of too little or too much are noteworthy because of their rarity. 

EDTA (ethylenediaminetetraacetic acid) extracts of soils tend in general to correlate well with plant contents, in particular with the plant-available fraction for Cd, Cu, Ni, Pb and Zn [208-210], EDTA (0.05 mol at pH 7 was used in the certification of the two soils mentioned above [197]. This test is assumed to extract both carbonate-bound and organically-bound fractions of metals and was hence considered to be suitable for calcareous soil analysis. 

Other researchers have noted significant correlations between the amount of Mo extracted with anion resin and the plant content of Mo (Jarrell and Dawson, 1978 Lombin, 1985 Ritchie, 1988). In contrast. 

Literature Plant Contents (Structure) Remarks (Activity)... 

Carotenoids occur in the leaves, shoots and roots of all higher plants (content up to... 

Plant Content of oxalic acid in weight percent... 

The only element which appears to be taken up by plants at the levels of soil contamination normally found in urban areas, in amounts which could create a widespread toxic hazard for animals, is cadmium. Although this element is now generally present in enhanced levels in soils in urban and industrial areas, information is lacking on the corresponding increase in plant content of cadmium which must now be characteristic of such areas. 

SG-G8 Licences for nuclear power plants Content, format and 1982... 

BERROW M.L., DAVIDSON M.S. and BURRIDGE J.C. 1982. Trace elements extractable by 2-ketogluconic acid from soils and their relationship to plant contents. Plant and Soil, 66, 161-171. 

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