Patterns Of Nitrification Research Articles

Heterotrophic nitrification by Arthrobacter sp. (strain 9006) as influenced by different cultural conditions, growth state and acetate metabolism

An Arthrobacter sp. (strain 9006), isolated from lake water, accumulated nitrite up to about 15 mg N/l, but no nitrate. In a mineral medium supplemented with tryptone, yeast extract, acetate and ammonium, the cells released nitrite into the medium parallel to growth or when growth had virtually ceased. The nitrite formed was proportional to the initial acetate concentration, indicating an involvement of acetate metabolism with nitrification. The organism grew with a wide variety of organic carbon sources, but washed cells formed nitrite from ammonium only in the presence of citrate, malate, acetate or ethanol. Magnesium ions were required for nitrification of ammonium and could not be replaced by other divalent metal ions. Analysis of the glyoxylate cycle key enzymes in washed suspensions incubated in a minimal medium revealed that isocitrate lyase and malate synthase were most active during the nitrification phase. Nitrite accumulation but not growth was inhibited by glucose, tryptone and yeast extract. A possible explanation for the different nitrification patterns during growth is based on the regulatory properties of glyoxylate cycle enzymes.

Climate, Time, and Organisms in Relation to Podzol Development in Michigan Sands: I. Site Descriptions and Microbiological Observations

AbstractDirect microscopic counts of microflora, nitrification patterns, and water‐soluble organic matter production in upper humic horizons of seven soils were studied in an attempt to determine the processes responsible for correlations between forest types and Podzol development in Michigan.The volume and surface area of fungal mycelia, the number of bacterial cells, and the length of actinomycete filaments per gram of organic matter were substantially greater in a mull humus horizon under 100% northern hardwoods than in a mor humus horizon under a forest stand dominated by hemlock.Maximum crenic acid production occurred in the mor humus horizons, these being associated with forest stands dominated either by hemlock or white pine. Leachates from these horizons contained no nitrate until incubated with periodic leaching for over 5 months. In a mull and a duff mull horizon, nitrification was nil during the period of maximum crenic acid production and the initial appearance of nitrate was closely accompanied by sharp decreases in pH of the leachates and sharply reduced production of crenic acid.Data obtained in these studies point to mor humus layers (Oh or O2 horizons) as a major site of production of water‐soluble organic materials having properties which suggest that they may be active agents in podzolization and contribute to the composition of Podzol illuvial horizons. Production of these materials is intimately linked with patterns of nitrogen transformation peculiar to forest soils, notably under conifers.

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.

Effects of some phenylamide herbicides and their degradation products on soil nitrification

The effects on nitrification as studied by soil perfusion techniques of the herbicides 3′, 4′-dichloro-propionanilide (propanil), 3-(3, 4-dichlorophenyl)-1, 1-dimethylurea (diuron), 3-(3, 4-dichlorophenyl)-1-methoxy-1-methylurea (linuron), and the compounds 3-(3, 4-dichlorophenyl)-1-methylurea (DMU), 3, 4-dichlorophenylurea (DU), 3, 4-dichloroaniline (3, 4-DCA), and 3, 3′,4, 4′-tetrachloroazobenzene (TCAB) are reported. Propanil at a concentration of 100 μg/g of soil resulted in marked retardation of the nitrification process for about 2 months. High application rates of linuron, diuron, DU, and TCAB were required to inhibit nitrification. Among the degradation products, 3, 4-DCA inhibited the oxidation of NH4-N to NO2-N, but was inactive against the organisms oxidizing NO2-N to NO3-N. DMU inhibited the oxidation of NO2-N to NO3-N by Nitrobacter spp., resulting in accumulations of NO2-N in soil from NH4-N. Moreover, the presence of DMU could be detected within 1 month after application of either linuron or diuron to soil by the changes in normal nitrification patterns. The significance of antimicrobial activity of the herbicides and degradation products is discussed.

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.

Influence of Environmental Factors on the Nitrogen Cycle in Water

Understanding the behavior of impounded water is essential to the evaluation of any project involving streamflow regulation for water quality. Since 1962, the Engineering Activities Section of the Basic and Applied Sciences Program of the Federal Water Pollution Control Administration has been studying this subject, as specified in amended P.L. 87‐660. The study presented in this article was one in a series, designed to investigate the influence of natural environmental factors on the nitrogen cycle. There have been many studies of natural environments, but few controlled studies to demonstrate the influence of environmental factors on the rate and extent of nitrification. Equipment and methods are discussed, along with typical nitrification patterns, seed concentration, ammonia nitrogen concentration, relative turbulence, nitrites and nitrates, organics, and bacterial enumeration.