Nitrite Transformations in California Soils

Abstract

AbstractIncubation studies of factors influencing nitrite oxidation in four California soils were conducted at two temperatures—45° and 75° F. In acid soils nitrite transformations were found to be highly sensitive to nitrite concentration in the soil and were inhibited by very low levels. Nitrite had less effect on the second step of nitrification in alkaline soils. Nitrite oxidizers were shown to be very sensitive to low temperature soil conditions.Although nitrite disappeared rapidly following addition to acid soils, little nitrate was produced during the incubation period. Much of the nitrite‐nitrogen was lost from the system. Experiments using acid soils which had been sterilized showed similar losses in added nitrite‐nitrogen and lead to the conclusion that these losses result from nonbiological processes. Studies to determine the nature of these losses suggest nitrogen gas as the principal product.Investigations of respiration rates of the soil population where various concentrations of nitrite were added reveal that nitrites inhibit the respiratory activity of the soil microorganisms as a whole and not merely the nitrifying group. Very low concentrations were inhibitory in acid soils; however, in a calcareous soil more than a hundred‐fold increase in nitrite concentration was required to achieve the same magnitude of respiratory inhibition.