The extraction and definition of non-exchangeable or fixed ammonium in some soils from southern New South Wales

Abstract

The amounts of non-exchangeable or fixed NH4+ in six soils from southern New South Wales were determined by using three methods. Using a potassium hydroxide pretreatment 2-13 % of the total nitrogen in the surface soils was fixed and between 16 and 33 % in the subsoils. Different methods showed up to a threefold difference in the amount on some soils and non-significant differences in others. The interpretation of the part played by this fraction of soil nitrogen in the chemical and biological equilibrium of soil must be qualified according to the extraction method used. The use of soil samples having a larger particle size (< 2 mm) than previously used (<0.147 mm) was found to be adequate with the soils studied. As the present definition of non-exchangeable or fixed NH4+ is misleading, it is proposed that this fraction of soil nitrogen be called intercalary ammonium (NH4+). Intercalary NH4+ is defined as that nitrogen recovered from within clay minerals by hydrofluoric-hydrochloric acid treatment, subsequent to a potassium hydroxide or potassium hypobromite/potassium hydroxide pretreatment and 0 . 5N potassium chloride leaching to remove exchangeable NH4+ and organic nitrogen from the outside of the clay particles.

Fixation and defixation of ammonium in soils: a review

“…Similarly, Moyano and Gallardo (1988) also obtained significantly lower values with the method of Mogilevkina (1964) as compared to that of Silva and Bremner (1966). The method of Silva and Bremner (1966) gave higher values than the Dhariwal and Stevenson (1958), Bremner (1959), and Mogilevkina (1964) methods and lower values than the Rodrigues (1954) and Schachtschabel (1960) methods (Silva and Bremner 1966;Osborne 1976a). Dixit and Mir (1987) compared the methods proposed by Rodrigues (1954), the modified Rodrigues method (Bremner et al 1967) and those by Dhariwal and Stevenson (1958), Bremner (1959), and Silva and Bremner (1966) on ten soils varying in clay content from 12% to 31%.…”

“…McBeth (1917) defined the unrecovered portion of the added NH 4 + as "fixed NH 4 + " (henceafter refered as NH 4 + f ). The fixation of NH 4 + is defined as "the adsorption or absorption of ammonium ions by the mineral or organic fraction of the soil in a manner that they are relatively unexchangeable by the usual methods of cation exchange" (Osborne 1976a;SSSA 1984). Osborne (1976a) suggested "intercalary NH 4 + " and Mengel and Scherer (1981) "non-exchangeable NH 4 + " to distinguish between the NH 4 + recovered from clay minerals by digestion of the soil with 5 N HF:1 N HCl and NH 4 + which is bound organically or as NH 4 -phosphate (Frye and Hutcheson 1981).…”

“…The fixation of NH 4 + is defined as "the adsorption or absorption of ammonium ions by the mineral or organic fraction of the soil in a manner that they are relatively unexchangeable by the usual methods of cation exchange" (Osborne 1976a;SSSA 1984). Osborne (1976a) suggested "intercalary NH 4 + " and Mengel and Scherer (1981) "non-exchangeable NH 4 + " to distinguish between the NH 4 + recovered from clay minerals by digestion of the soil with 5 N HF:1 N HCl and NH 4 + which is bound organically or as NH 4 -phosphate (Frye and Hutcheson 1981). While earlier investigations concluded that only a very small amount of NH 4 + f is available to microorganisms and plants (Allison et al 1951(Allison et al , 1953bAxley and Legg 1960;Lutz 1966), studies in the last three decades suggest that NH 4 + f may be released and used by crops (Kudeyarov 1981;Nommik 1981;Mengel and Scherer 1981;Nommik and Vahtras 1982;Preston 1982;Scherer 1984Scherer , 1987Scherer , 1993Lu et al 2010).…”

Measurement and simulation of soluble, exchangeable, and non-exchangeable ammonium in three soils

“…Ammonium fixation in its non-exchangeable form is defined as "the adsorption or absorption of ammonium ions by the mineral or organic fraction of the soil in a manner that they are relatively unexchangeable by the usual methods of cation exchange" (Osborne, 1976b, as cited by Nieder et al, 2011). Fixation occurs mostly in the interlayer regions of 2:1 clay minerals, such as illite, vermiculite, and montmorillonite.…”

Variations in the cation exchange capacity of a ferralsol supplied with vinasse, under changing aeration conditions

“…For example, K + may be trapped in the clay interfoliar space and reduce its thickness (Khaled and Stucki, 1991), and then exchanges more easily with NH 4 + than with other cations (Ciesielski and Sterckeman, 1997b). Trapping of NH 4 + (Osborne, 1976;Evangelou and Lumbanraja, 2002) and Cs radionuclides (Hird et al, 1996) have also been observed. It has been shown that CEC varies with the amount and nature of the soil clay, soil organic matter content and solution pH, although the proportion of pH dependent charges varies with the solids (Brady and Weil, 2002).…”