Nitric Oxide Production In Soil Research Articles

The contributions of hydroxylamine and nitrite to NO and N2O production in alkaline and acidic vegetable soils

The contribution of hydroxylamine (NH2OH) and nitrite (NO2−) to nitric oxide (NO) and nitrous oxide (N2O) production remains unclear in vegetable production soils. Soils collected from six typical greenhouse vegetable fields were incubated for 48 h following amendment with 1 mM NaNO2, 10 μM NH2OH, or 1 mM NaNO2 + 10 μM NH2OH. The importance of abiotic processes on the NO and N2O formation from the NH2OH and NO2− were studied by irradiating the soil samples with γ-irradiation. NO2− amendment significantly stimulated NO production, while the NH2OH-dependent NO production was minimal. NH2OH stimulated more abiotic N2O production in alkaline soils than in acidic soils (p < 0.05), while NO2− stimulated more biotic N2O production in acidic soils than in alkaline soils (p < 0.05). The NH2OH- and NO2−-dependent sources produced biotic or abiotic N2O with site preference (SP) values of 27.4–36.5‰, which is similar to those from ammonia-oxidizing archaea (AOA) or ammonia-oxidizing bacteria (AOB) sources (25.1–34.2‰), indicating that abiotic N2O production were closely linked with biotic NH3 oxidation. The variability of NO2−+NH2OH-induced N2O production can be explained by the soil organic carbon and iron concentrations, whereas NO2−-induced NO production can be explained by the soil pH. NO2− addition dominated NO production in all soils. Furthermore, NO2− addition increased biotic N2O production in acidic soils, while NH2OH addition increased abiotic N2O production in alkaline soils. The presence of NO2− could significantly stimulate the abiotic conversion of NH2OH to N2O in soils with low soil organic carbon and high iron concentrations. Thus, assessing the abundance of NH2OH and NO2− could provide crucial information for understanding NO and N2O production procedures in vegetable soils. • The chemical decomposition of NO2− dominated NO production in all soils. • The NH2OH stimulated abiotic N2O production in alkaline soils. • The NO2− stimulated biotic N2O production in acidic soils. • The SP for abiotic NO2−-/NH2OH-related N2O were in the same range as AOB/AOA sources.

Soil-air exchange of nitric oxide: An overview of processes, environmental factors, and modeling studies

Terrestrial ecosystems with their main elements soil and plants may act, in principle, as both source and sink for atmospheric nitric oxide (NO). The net exchange between ecosystems and the atmosphere, however, is globally dominated by biogenic emissions of NO from soils. Consequently the soil–air exchange of NO is the focus of the following overview. Particular emphasis is placed on the major processes that are responsible for NO production in soils (nitrification, denitrification) and their regulation by environmental factors (nitrogen availability, soil water content, soil temperature, ambient NO concentration). It is shown that interactions of these factors are a major reason for the broad range that exists in published data on NO fluxes. This variability makes it difficult to predict the magnitude of NO fluxes on relevant spatial and temporal scales. To overcome the problem various generalization procedures for scaling up in space and time have been developed, and the potential and limitations of the different approaches is discussed.

Effect of Acetylene on Nitric Oxide Production in Soil under Denitrifying Conditions

Acetylene inhibition of N2O reduction to N2 is traditionally used to estimate denitrification. Although NO is also produced in the denitrification process, the effect of C2H2 on NO production in denitrification has not previously been examined, mainly because C 2 H 2 interferes with chemiluminescent analysis of NO. We used a gas-flow system to study the effect of C2H2 on NO and N2O production in soil columns under denitrifying conditions and developed a method to avoid C2H2 interference of NO analysis. Nitric oxide, N 2 O, and C 2 H 2 were measured in NO 3 - -amended Brookston clay loam (fine-loamy, mixed, mesic Typic Argiaquoll) and Fox sandy loam (fine-loamy over sandy or sandy-skeletal, mixed, mesic Typic Hapludalf) with various moisture contents with and without added glucose during 50-h anaerobic incubations. In glucose-amended Brookston soil with =8% C 2 H 2 added to the N2 carrier gas, net NO production rates were increasingly inhibited after the first 24 h, and by 50 h were only 2 to 7% of the rates obtained in the absence of C 2 H 2 . Without glucose amendment and with C 2 H 2 , net NO production rates decreased by 24 to 62% in the Brookston soil. In the Fox soil inhibition occurred almost immediately on C2H2 addition and net NO production during 50 h was reduced by 36 to 62% with glucose amendment, and by 65 to 76% without glucose amendment. In most cases, net N 2 O production rates were decreased by C2H2 due to the decrease in production of its precursor, NO, and in some cases, increased due to inhibition of N 2 O reduction to N 2 . Our data suggest that the C2H2 inhibition method may underestimate total denitrification rates under low water contents or high levels of C substrate.

A model relating laboratory measurements of rates of nitric oxide production and field measurements of nitric oxide emission from soils

An explanatory model that relates laboratory measurements of nitric oxide (NO) production in soil to field measurements of the diffusive flux of NO from the same soil to the atmosphere is presented. Microbial NO production in soils is represented by a production term independent of, and an uptake term with first‐order dependence on, NO concentration. These production and first‐order uptake terms can be measured in flow‐through soil columns. Within the model, representing a field soil, the divergence in vertical diffusive flux of NO is represented by the production minus uptake and so a flux to the atmosphere is calculated. At Kjettslinge, Sweden, a field flux of NO of 2 − 17 × 10−9 g N m−2 s−1 was observed under aerobic conditions, while laboratory measurements and the model give a calculated flux of NO for the same soil under the same environmental conditions of 3 − 11 × 10−9 g N m−2 s−1. Thus the results suggest that laboratory measurements on a specific soil may be used to determine the field flux from the same soil under certain well specified conditions.