Evaluation of the acetylene inhibition method for measuring denitrification in soilless plant culture systems

• Published in: Biology and fertility of soils Vol. 24; no. 1; pp. 111 - 117
• Main Authors: Daum, D, Schenk, M.K
• Format: Journal Article
• Language: English
• Published: Berlin Springer 01.01.1997; Springer Nature B.V
• Subjects: acetylene; Agronomy. Soil science and plant productions; Air flow; Biochemistry and biology; Biological and medical sciences; carbon dioxide; Chemical, physicochemical, biochemical and biological properties; concentration; Cucumis sativus; Denitrification; determination; diurnal variation; Emissions; Environmental conditions; Fumigation; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Generalities; greenhouse production; inhibition; length; losses; Lycopersicon esculentum; measurement; microbial activity; nitrogen; nitrous oxide; oxygen; Oxygen consumption; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Plant growth; reduction; Root zone; Roots; seedling growth; Seedlings; shoots; Soil science; soilless culture; Soilless cultures. Co2 fertilization; Soilless cultures. Protected cultivation; Soils; Solanum lycopersicum var. lycopersicum; spatial variation; Sulfuric acid; Tomatoes; weight; Microbial activity; Gas emission; Horticulture; Growth; Nutrient solution; Protected cultivation; Acetylene; System performance; Acetylene inhibition method; Dicotyledones; Angiospermae; Lycopersicon esculentum; Solanaceae; Soilless cultivation; Root; Cucurbitaceae; Cucumis sativus; Nitrogen cycle; Nitrogen Molecules; Vegetable crop; Denitrification; Soil biology; Spermatophyta; Measurement method; Nitrogen protoxide
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/BF01420230

Denitrification measurements by means of the acetylene inhibition method require a continuous presence of acetylene to block the microbial reduction of N2O to N2. To examine the effect of such steady exposures on the growth of plants, roots of cucumber and tomato seedlings were treated with different acetylene concentrations. Acetylene concentrations of greater than or equal to 1 vol% in the gas phase, which were necessary for complete inhibition of N2 formation, led to a significant retardation of root growth. This was partly due to trace amounts of ethylene contained in the acetylene gas which could not be removed with the usual prescrubbing through a sulfuric acid train. As a result of the growth impairment, oxygen consumption in the root zone decreased after 4 days of exposure. In order to avoid these side effects, the denitrification measurements in soilless cultures were performed on individual plants over a limited period of 2-3 days. The flow-through chamber method proved to be suitable for determining the gaseous N losses in a closed-loop system. It avoided greater air variations from the environmental conditions (substrate temperature, airflow and plant composition) and excluded errors in measurement caused by injury to roots and spatial variability of denitrification activity in the root medium. For exact estimation of the gaseous N losses, preceding 24-h acetylene fumigation was necessary. Subsequently at least three gas samples had to be taken throughout the day, because the N2O+N2 emissions were subject to a pronounced diurnal variability.