Nitrifying Organisms Research Articles

Competition Between Species During Nitrification in Soil

AbstractPreviously we have derived equations which describe populations of nitrifying organisms growing in an idealized soil column perfused with nutrient solutions. Population growth in the soil column at any particular depth is here discussed in terms of a kinetic model that allows for exhaustion of nutrient or space, i.e., surface area limitation, whether or not death occurs, and competition between two species in the same niche. The model in its various ramifications is subject to laboratory tests and points up inadequacies in current understanding of the microscopic ecology of nitrification.

Consequences of banding nitrogen fertilizers in soil

An account is given of the interactions which occur when urea or ammonium sulphate is banded in a clay soil. The spatial distributions of ammonium, nitrate, and nitrite around the band are given as functions of time and are discussed in relation to results from a series of incubations of homogeneous mixtures of various nitrogen compounds and soil. The diffusion of the banded fertilizers and their products through the soil presents the nitrifying organisms with a wide range of environments. The patterns of nitrification are therefore complicated. Nevertheless, they are explicable in terms of the main results of the incubations which were that (a) nitrification was completely inhibited if the osmotic suction of the soil solution was higher than 10 bars, if the ammonium-N concentration in the soil solution was above 3000 ppm, or if the pH was greater than 8, (b) nitrite accumulated if the pH was between 7 and 8, (c) nitrate accumulated if the pH was less than 7, and (d) above a minimum concentration of fertilizer the rate of nitrate formation was independent of the concentration unless the latter was so high that either pH, osmotic suction or ammonium concentration became inhibitory.

Kinetics of Nitrification in Soil: Growth of the Nitrifiers

Nitrification leads to growth of nitrifiers but also includes both maintenance and waste metabolism. The relative proportions of the three kinds of metabolism have yet to be measured, but waste and maintenance together are known to predominate. Rates of nitrification may be taken as proportional to growth of nitrifiers provided populations are small compared to the carrying capacity of the environment and provided that substrate concentrations are high enough to yield maximum specific growth rates. This applies to growth and metabolism in both batch culture and column perfusion studies. Equations have been derived which describe populations of nitrifying organisms as functions of depth of columns being perfused with nutrients (ammonium or nitrite) and nutrient concentration profiles in an idealized soil. Typically, growth of nitrite oxidizers will lag behind ammonium oxidizers behind the flow front during perfusion of short soil columns with ammonium.

Effect of Dyrene and Maneb on Nitrification and Ammonification, and Their Degradation in Tropical Soils

AbstractThe effect of 2,4‐dichloro‐6‐(o‐chloroanilino)‐s‐triazine (dyrene) and manganese ethylene bisdithiocarbamate (maneb) at 0, 15, 60, 240, and 960 ppm on nitrification of 100 ppm applied NH4‐N, and on ammonification of soil nitrogen, and the degradation of these fungicides, were studied in a lateritic clay and a fertile loam incubated at 24C for 16 weeks.Inhibition of nitrification by the fungicides was lesser and of shorter duration in the rapidly nitrifying loam than in the slow nitrifying lateritic soil. The chemicals inhibited the ammonia oxidizing bacteria but not the nitrite oxidizing bacteria. Maneb was several times more toxic to the nitrifying organisms than dyrene, and its effect lasted even after the chemical was degraded. Ammonification was inhibited only at 960 ppm of the fungicides. There was no synergistic effect with regard to inhibition of nitrification or ammonification when the soil received both the fungicides. The fungicides were degraded faster in the rapidly nitrifying soil than in the slow nitrifying soil. Maneb was decomposed earlier than dyrene.

Nitrification in Soil: Systems Approaching a Steady State

AbstractEquations are set up for the consecutive reactions NH4+ → NO2‐ → NO3‐ in an idealized soil column and solved, for an open system with a constant rate of entry of a solution of ammonium, for concentrations of ions as functions of time of flow and distance within the column. The equations take into account growth of nitrifying organisms but it is assumed that diffusion and ion exchange within the soil and fixation of nutrients by the nitrifiers are of secondary importance.

Accumulation of nitrate in fresh soils after gamma irradiation

SUMMARYIncreases in nitrate have been found in eight out of ten soils irradiated over the range 0·25–2·5 Mrad, with maximum accumulation between 0·25–0·75 Mrad. Oxidation of ammonium added to normal soils was poor at low pH, and showed a highly significant correlation with nitrate produced after 0·25 Mrad. It is suggested that radiation-released ammonium is less limiting to nitrate formation than the original population or activity of nitrifying organisms, which are favoured by alkaline conditions.

Studies on the environmental conditions controlling nitrification in soil

Abstract As reported in the first part of this work (4), it is clear that concentration of ammonium ion and total salt in soil solution has a great effect on the rate of nitrification. Cationexchange materials in soil regulate concentration of ammonium ion in soil solution, and may be favorable as a habitat for soil microorganisms including nitrifying organisms. Therefore, nitrification in soil solution would be affected by cation-exchange materials in soil. LEES and QUASTEL (5) aroused attention as to the importance of the effects of colloidal soil particles on microbial activity. Very few researches (3,5,6), however, have been made on these properties of the cation-exchange materials in soil that affect the rate of nitrification, and moreover, some of the data reported are conflicting and inconclusive.

Interrelations of micro-organisms and mulberry

Evidence has been presented to show that the autotrophic nitrifying organisms get stimulated in the mulberry rhizosphere. Three species of Pseudomonas, one each of Achromobacter and Bacillus capable of degrading methionine were shown to be stimulated in the rhizosphere. These bacteria were capable of reversing the inhibitory effect of methionine on soil nitrification. Two of them were able to form nitrite from methionine. The possibility that the increased nitrifying activity in the mulberry rhizosphere in the presence of methionine found in mulberry root exudations was the result of the activity of these organisms was suggested.

Patterns Observed for the Oxidation of Ammonium to Nitrate by Soil Organisms

AbstractAmmonium sulfate solutions were percolated for 28 days through samples from the top two horizons of 55 soils derived from several classes of glacial tills and through six calcareous horizons influenced by sodium. Four general nitrification patterns were observed:(I) Ammonium rapidly oxidized to nitrite which accumulated over a long period before being oxidized to nitrate. (II) Ammonium and the produced nitrite both rapidly oxidized. (III) Ammonium slowly oxidized to nitrate without nitrite appearing. (IV) Ammonium oxidation not detectable by either nitrite or nitrate formation.The occurrence of the four patterns was correlated with soil reaction and other acidity related properties. Nitrosomonas spp. and Nitrobacter spp. organism numbers and proliferation characteristics influenced by soil environment accounted for the four nitrification patterns observed except insufficient Nitrobacter spp. organisms were detected to produce the nitrate formed in type III soils.Nitrification patterns were modified by altering the soil properties and the number of nitrifying organisms consistent with the above interpretations. Ammonia, nitrite, nitrate, and pH affected Nitrobacter spp. lag in type I soils.

Some factors in low‐temperature storage influencing the mineralisable‐nitrogen of soils

AbstractThe effect of storing soils at −20° on their subsequent ability to mineralise nitrogen on incubation differs according to the soil, because significantly more mineral‐N (ammonium‐and nitrate‐N) and nitrate‐N was produced by three of four soils tested. These increases, apparently induced by freezing and thawing, may have been partly related to the moisture and carbon contents of the soils. Samples stored for different periods up to 6–9 months differed little in their rates of mineralisation. Experiments with added ammonium‐N suggested, however, that numbers of nitrifying organisms decreased after 6 months storage.

EFFECT OF MIXING VARYING QUANTITIES OF DICYANDIAMIDE WITH AMMONIUM FERTILIZERS ON NITRIFICATION OF AMMONIA IN SOILS

A series of laboratory experiments were conducted to evaluate the effect of dicyandiamide on the transformation of fertilizer nitrogen in Georgia soils. These studies indicated that dicyandiamide inhibited nitrification of ammonium sulphate at all rates utilized. The inhibitory action of dicyandiamide was attributed to its toxic effect on the nitrifying organisms which failed to function in the presence of dicyandiamide. Complete nitrification eventually occurred but only after a long period.Decomposition of dicyandiamide was more rapid in fine-textured Cecil sandy loam containing relatively more organic matter than on the coarse-textured and low organic matter Lakeland sandy soil. Soil texture and organic matter content are two factors that must be considered in evaluating the length of time that dicyandiamide will inhibit nitrification in any given soil.Sucrose apparently provided a quickly available source of energy for soil microorganisms that utilized the dicyandiamide as a source of nitrogen and preventing its inhibiting effect on nitrification. The nitrogen from the dicyandiamide was eventually mineralized as indicated by the higher total ammonium and nitrate nitrogen found at the end of incubation period.

An Organelle confined within the Cell Wall of Nitrosocystis oceanus (Watson)

ONE of us isolated a nitrifying organism from the open ocean and called it Nitrosocystis oceanus1. In the course of examining this organism, observations were made on the fine structures shown in sections of embeddings made in ‘Vostopal W’ following the preparative prescriptions of Ryter and Kellenberger2,3. A number of structural peculiarities were observed, which will be described in a separate paper, and among them there was a structure that seems to be without precedent so far as wo are aware. It was an organelle of regular and recognizable form lying between the major layers which make up the cell wall of this bacterium.

The biochemistry of the nitrifying organisms. 6. The effect of oxygen concentration on nitrite oxidation in the presence of different inorganic ions

The biochemistry of the nitrifying organisms. 6. The effect of oxygen concentration on nitrite oxidation in the presence of different inorganic ions

XVII. Nitrifying activities of two cultivated Soils

Summary Nitrifying organisms occurred in the soils of two New Zealand tussock grasslands. The nitrifying activity of Taupo soil was less in the vicinity of the roots of Festuca tussock plants than in soil at a distance from these plants but little difference was found between the samples of Cass soil. These and previous results indicated that growing Festuca tussock plants do not stimulate the activity of nitrifying organisms in these tussock-grassland soils. The nitrifying activity of the Taupo soil was generally greater in summer than in spring but no seasonal differences were found in the strongly acid Cass soil which had a low nitrifying potential. In both soils, a significant increase in nitrifying activity resulted after growth of crops or introduced pastures, following preliminary ploughing and the addition of fertilisers. The activities of these cultivated tussock-grassland soils were similar to those of three other cultivated soils that were originally under forest.

The Formation of Nitrate from Ammonium Nitrogen in Soils: III Influence of Temperature and Initial Population of Nitrifying Organisms on the Maximum Rate and Delay Period

AbstractA number of soils of varying properties were incubated at several temperatures and rates of inoculation of nitrifying organisms to determine the influence of these factors on nitrification. The time‐nitrification curve generally exhibited a “delay” phase and a “maximum rate” phase followed by a phase in which the rate of nitrification declined as the substrate was exhausted and the end product concentration increased. Each phase must be measured and characterized before difference in nitrification in soils can be fully understood and described.In soils incubated at field capacity, the maximum nitrification rates increased from immeasurably low values to as great as 900 ppm. per week in some soils and the delay periods decreased from about 32 weeks to < 1 day, as temperatures increased from 0 to 25° C. Increase in initial population of nitrifying organisms caused decreases in delay periods but did not appreciably affect the maximum rate above 10° C. The influence of temperature and nitrifying population on delay periods and maximum rates varied greatly among soils indicating that other factors inherent in the soils also affect nitrification.

Effect of temperature on nitrification in soils

Abstract Nitrification plays an important role in nitrogen transformation in soils. As a practical problem the fact is noteworthy that by nitrification, the loss of nitrogen from soils is caused at higher temperatures in the summer. On the contrary, it is quite slow at the lower temperatures of early spring. Recently much Work has been done on the effect of temperature on nitrification in soils. It was noticed that its effect is not the same according to the difference of soils. Soils which have high nitrifying activities at ordinary temperatures (around 25°C) show fairly good nitrification even at lower temperatures (1, 2, 5). However, in nitrification by usual experimental methods, the amount of nitrate produced can be only estimated while nitrifying organisms are increasing or decreasing in soil. As the growing Process of microbes is extremely influenced by both the properties of the soil and the cultural conditions, it is necessary to examine the effect of temperature on the growing process of microbe...

Biological studies of some tussock-grassland soils

Summary Nitrifying organisms occur in the soils of three New Zealand tussock grasslands. A low nitrifying potential, particularly for the oxidation of nitrite, is shown by the moderately to strongly acid Tekoa soil near Bealey. The Taupo soil near Waiouru and the Omarama soil near Alexandra show much greater activity. An increase in activity has not been found at the base of Festuca tussock plants. The effect of seasons upon nitrifying activity has been briefly studied.

On a method for isolation of Nitrifying Organisms

Abstract Silica gel plate method has been considered for a long time most useful for the isolation of nitrifying organisms. However, even this method is not always good and sure. In most cases workers must try experiments many times to gain a pure culture by chance, even though the possibility of success by this method is somewhat higher than by other method such as dilution method in liquid media. The reason for this difficulty of their isolation seems to lie in the fact that in ordinary soils, the number of general soil microbes is much larger than that of nitrifying organisms and within the lower degree of dilution, the contamination of their colonies by other microbes is liable to take place.

The biochemistry of the nitrifying organisms. V. Nitrite oxidation by Nitrobacter.

The biochemistry of the nitrifying organisms. V. Nitrite oxidation by Nitrobacter.

Estimation of numbers of Nitrosomonas in soil and culture.

ATTEMPTS to estimate the numbers of nitrifying organisms in soil have usually been made by some form of dilution technique involving culture of the dilutions in liquid media in tubes (see ref. 1). The number of dilutions, and of replicate tubes at each dilution, that are necessary to give reliable estimates, makes this method extravagant of material and time.