Manganese plant availability

Warden B.T., Reisenauer H.M. Fractionation of soil manganese forms important to plant availability. Soil Sci Soc Am J 1991 55 345-349. 

Hoyt PB, Nyborg N. Use of dilute calcium chloride for the extraction of plant available aluminum and manganese from acid soil. Can. J. Soil Sci. 1972 52 163-167. 

Hoyt, P.B. and Nyborg, M. (1971b) Toxic metals in acid soils. II. Estimation of plant-available manganese. Soil Sci. Soc. Am. Proc., 35, 241-244. 

Wright, A.J., Baligar, VC. and Wright, S.F. (1988) Estimation of plant-available manganese in acidic subsoil horizons. Commun. Soil Sci. Plant Anal, 19, 643-662. 

Some laboratories employ operationally defined procedures to extract total elements from soils, such as a one hour reflux with a mixture of boiling nitric and hydrochloric acids. Such an approach may be adequate, for example, to study the build up of elements such as zinc, cadmium, copper, lead, and nickel in sludge-treated soils. However, operationally defined procedures are much more often used to extract the portions of elements present in soils and sediments in a labile or plant-available form. For example, solutions of EDTA or CDTA may be used to extract copper, zinc, manganese, and iron from soils,17 or hydroxylamine hydrochloride may be used to extract easily reducible manganese or manganese oxide-bound trace elements.6... 

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. 

In anaerobic soils, the individual chemistry of the ions is more distinctive. The transition metal ions in the middle of each period of the periodic table—chromium, manganese, iron, nickel, cobalt, and copper—can reduce to lower oxidation states, while the end members—scandium, titanium, and zinc—have only one oxidation state. The lower oxidation states are more water soluble but still tend to precipitate as carbonates and sulfides, or associate with organic matter, thus reducing their movement but increasing then plant availability. 

The manganese, iron, cobalt, copper, zinc, and molybdenum ions of this group are all essential for plants and animals. In addition, vanadium, chromium, nickel, and tin are essential for animals. The soil solution concentrations and plant availabilities of these ions generally decline with increasing pH. Molybdenum is an exception and becomes more available with increasing pH. Reducing conditions dissolve Mn2+ andFe2+. 

Reisenauer, H.M., 1988. Determination of plant-available soil manganese. In Graham, R.D., Hannam, R.J., Uren, N.C. (Eds.), Manganese in Soils and Plants. Kluwer Academic Publishers, The Netherlands, pp. 87-95. 

A detailed review of the methods for deterrnination of low manganese concentration in water and waste is available (179). A review on the speciation of Mn in fresh waters has been reported (180). Reviews for the chemical analysis of Mn in seawater, soil and plants, and air are presented in References 181, 182, and 183, respectively. 

Soil pH is easily tested for and determines the availability of nutrients and the success of white clover. Very acid soils (below pH 5.0) will cause a deficiency of the trace elements iron, boron, copper and molybdenum and conversely will cause injury to plant growth by increasing the availability of aluminium and manganese to toxic levels. Over-liming, on the other hand, which can raise the pH above 6.5, will reduce the availability of certain essential elements such as phosphorus, manganese and boron. 

Schwab A.P., Lindsay W.L. The effect of redox on the solubility and availability of manganese in a calcareous soil Rice plants. Soil Sci Soc Am J 1983 47 217-220. 

The first consideration was the speciation and distribution of the metal in the sediment and water. Benthic organisms are exposed to surface water, pore water and sediment via the epidermis and/or the alimentary tract. Common binding sites for the metals in the sediment are iron and manganese oxides, clays, silica often with a coating of organic carbon that usually accounts for ca. 2% w/w. In a reducing environment contaminant metals will be precipitated as their sulfides. There is not necessarily a direct relationship between bioavailability and bioaccumulation, as digestion affects the availability and transport of the metals in animals, in ways that differ from those in plants. 

Localized spots of decomposing oigauicmattei aie important in reducing small but important quantities of iron to ferrous form and manganese to divalent form so that they become available to plants. Moderately to highly alkaline soils sometimes have inadequate activity of the reduced forms of iron and manganese, particularly in the absence of sufficient organic matter. 

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