Determination of Fixed Ammonium in Soils

Fixation and defixation of ammonium in soils: a review

“…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%. The highest values were obtained in the method of Rodrigues and the lowest by the method of Bremner.…”

“…In the method by Mogilevkina (1964), soil organic matter is removed by dry combustion at 400°C during time periods between 24 and 72 h, depending on the organic matter content, prior removal of the fixed NH 4 + using sulfuric acid (Kjeldahl procedure). Most of the other methods use HF for the extraction of NH 4 + f (Rodrigues 1954;Dhariwal and Stevenson 1958;Bremner 1959). The method proposed by Silva and Bremner (1966) is the most commonly used and involves treating the soil with alkaline KOBr solution (to remove organic compounds), washing the residue with 0.5 M KCl and shaking with 5 N HF:1 N HCl for 24 h. The 24 h time for HF-HCl treatment could be reduced to 30 min by performing the treatment at 100°C.…”

Determinação das formas de nitrogênio e nitrogênio total em rochas-reservatório de petróleo por destilação com arraste de vapor e método do indofenol

“…As amostras 73319 e 73321, que apresentaram N orgânico como forma predominante de nitrogênio, apresentaram picos indicativos da presença de feldspatos. De acordo com a literatura 32,35 , os minerais illita, muscovita, clorita e feldspatos são potencialmente fixadores de nitrogênio, sendo que a illita é um dos principais minerais responsáveis pela fixação do íon N-NH 4 + . Portanto, os resultados indicam que provavelmente a forma de nitrogênio está relacionada à composição mineralógica da amostra.…”

Determination of fixed ammonium in soils

“…However, it is now well established that many soils have the capacity to fix ammonium (i.e., to adsorb ammonium in a manner such that it is not readily exchangeable) (Barshad, 1951;Allison et al, 1951Allison et al, , 1953bHanway and Scott, 1956;Nommik, 1957;Jansson, 1958;Stojanovic and uroadbent, 1960;Walsh and Murdoch, 1960), and recent work has shown that some soils contain significant amounts of fixed (i.e., nona exchangeable) ammonium which is not determined by the methods normally used for estimation of inorganic forms of nitrogen in soils (Rodrigues, 1954;Dhariwal and Stevenson, 1958;Stevenson and Dhariwal, 1959;Bremner and Harada, 1959;Walsh and Murdock, 1960;Schachtschabel, 1961a, b;Young, 1962;Young and Cattani, 1962). Present data indicate that the proportion of soil nitrogen as fixed ammonium usually does not exceed about 5% in surface soils, but that it can exceed 30% in certain subsoils.…”

“…The use of HF for determination of fixed ammonium in soils was originally proposed by Rodrigues (1954), but the HF treatment he adopted is very drastic, and there is evidence that it is subject to serious interference by soil organic matter . Dhariwal and Stevenson (1958) and have proposed milder HF procedures for estimation of fixed ammonium, and these methods have been used in most investigations concerning fixed ammonium in soils. However, Schachtschabel (1961b) has recently proposed an HF method involving a pretreatment with H2O2 to reduce interference by soil organic matter, and he found that this method gave much higher values than the Bremner's method.…”