Effect of Acidity on Nitrogen Mineralization and Nitrification in Atlantic Coastal Plain Soils

Abstract

The objective of this study was to determine the effect of acidity on mineralization, nitrification, and N2O evolution during these processes on naturally acid soils from the lower Coastal Plain of North Carolina. Six acid surface soils (pH ≤4.5) from the Tidewater region of North Carolina, with a range of organic matter (OM) contents (28‐850 g kg−1) were limed to give a range of pH values so that the effect of acidity on mineralization of organic N and nitrification of (NH4)2SO4 could be studied under controlled conditions in the laboratory. Cumulative net mineralization over 21 d was significantly (p <0.01) influenced by acidity in four of the six soils. However, no soil exhibited a significant net mineralization increase between the very acid initial pH value and the pH value to which liming is recommended (pH 4.8‐5.2 for Histosols) for crop production. Liming to pH values <7 increased net mineralization in only one soil. Adding a small increment of lime tended to decrease mineralization although this effect was significant in only one soil. Essentially all organic N mineralized was converted to NO‐3 at all pH values. However, the very high acidities tended to inhibit the nitrification of NH+4 added as (NH4)2SO4. There was apparently no influence of organic matter content on any of the processes studied except N2O evolution where the soils with <120 g OM kg−1 evolved the highest amounts of N2O during nitrification. Much of the N2O evolution was apparently due to denitrification because addition of nitrapyrin did not eliminate the evolution. It was concluded that the liming of acid soils in the Tidewater Region of North Carolina would have little influence upon N mineralization rates. The recommended pH values of 4.8 to 5.2 for Histosols appears to be adequate for both mineralization and nitrification.

Spatial variations of nitrogen trace gas emissions from tropical mountain forests in Nyungwe, Rwanda

“…It is well known that low pH decreases the activity of the N 2 O-reductase, thereby increasing production of N 2 O from denitrification (Nömmik, 1956;Weier and Gillam, 1986;Granli and Bockman, 1994). For nitrification, it has also been demonstrated that low pH values favor N 2 O production (Sitaula and Bakken, 1993;Martikainen and De Boer, 1993;Kesik et al, 2006).…”

Autotrophic Ammonia Oxidation at Low pH through Urea Hydrolysis

“…Nitrification has, however, been reported in acid soils at pH values as low as 3.7 (5,9,11,25,26,34,35,37). Although this may be due, in some cases, to heterotrophic nitrification (1,22) there is strong evidence for autotrophic nitrification in acid soils (19,38). Autotrophic ammonia oxidizers have been isolated from and enumerated in acid soils (7,13,16,20,26) and 16S rRNA gene sequences of ammonia oxidizers are frequently detected (6,33), with evidence for changes in relative abundance of different sequence clusters in soils of different pH (32).…”

Response of nitrifying bacteria in concretionary soil of Northern Ghana to phosphorus fertilization

“…Soils with pH value below 4.5 were observed to nitrify (Weber and Gainey 1962;Weier and Gilliam 1986) probably by acid adapted strains. Soil pH was insignificantly correlated with nitrifiers population, in contrast to the frequently reported negative relationship between pH and nitrifiers population (Dancer et al 1973;Gilmour 1984).…”