Date of Award:


Document Type:


Degree Name:

Doctor of Philosophy (PhD)


Plants, Soils, and Climate


R. L. Smith


Curiosity is the cause of investigations, and the thirst for knowledge originates from it. Many times at the end of investigations, the number of questions raised are greater than those for which answers are sought. Therefore, all the information gathered through scientific investigations may not be of value for immediate application in practical life. Nevertheless, no research can be considered less important than the other because the integration of several scientific findings considered less less important at the time of investigation may reveal something of very high significance. Similarly, the study of various transformation reactions that the added fertilizers undergo may not be of value to the one whose main objective is to increase production, though it is of great value for the efficient use of fertilizers. Information on the reactions of each intermediate compound produced during the transformations of ammoniacal fertilizers may be useful in reducing or preventing the loss of N that could arise through some of the reactions. Such knowledge will be useful for the economical use of fertilizers.

Nitrite is an intermediate compound produced in nitrification, denitrification, and nitrite reduction processes. Chemistry of nitrite in alkaline solutions is well understood, while its fate in acid soils and solutions has eluded the attention of most workers. This is probably due to the fact that under acid conditions nitrite does not appear in large quantities contrary to its behavior in the alkaline region. However, the existence of nitrite in smaller concentrations under acid conditions suggests the possibility that it may be rapidly transformed to other forms of N and may lead to the loss of added N. The rates of such reactions and losses may be higher in acid than in alkaline soils.

In acid solutions nitrite also exists as un-ionized nitrous acid; the concentration of the latter form increases at higher acidities. In the following pages these two terms, nitrite and nitrous acid, will be used interchangeably. In acid soils, nitrous acid undergoes several changes such as its fixation by various soil components, chemical conversion to other N compounds, and loss of N either as N2 or in the form of oxides of nitrogen. Most of these reactions may probably result in reduced nitrogen availability to the crops.

In this investigation some of the factors influencing nitrite transformations, such as non-biological nitrification and loss of N in different forms, were studied. Validity of some of the proposed nitrite decomposition pathways were verified, and conditions favoring individual reactions were studied in various soil and resin systems.