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Nitrification in a zeoponic substrateClinoptilolite is a zeolite mineral with high cation exchange capacity used in zeoponic substrates that have been proposed as a solid medium for growing plants or as a fertilizer material. The kinetics of nitrification has not been measured for NH4+ saturated zeoponic substrate. Experiments were conducted to evaluate the production of NO2- and NO3-, and nitrifier populations in zeoponic substrates. Small columns were filled with zeoponic substrate inoculated with a commercial inoculum or soil enrichment culture of nitrifying bacteria. In addition to column studies, a growth chamber study was conducted to evaluate the kinetics of nitrification in zeoponic substrates used to grow radishes (Raphanus sativus L.). The zeoponic substrate provided a readily available source of NH4+, and nitrifying bacteria were active in the substrate. Ammonium oxidation rates in column studies ranged from 5 to 10 micrograms N g-1 substrate h-1, and NO2- oxidation rates were 2 to 9.5 micrograms N g-1 substrate h-1. Rates determined from the growth chamber study were approximately 1.2 micrograms N g-1 substrate h-1. Quantities of NH4+ oxidized to NO2- and NO3- in inoculated zeoponic substrate were in excess of plant up-take. Acidification as a result of NH4+ oxidation resulted in a pH decline, and the zeoponic substrate showed limited buffering capacity.
Document ID
20040087445
Acquisition Source
Johnson Space Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
McGilloway, R. L.
(College Station TX, 77843-2474, United States)
Weaver, R. W.
Ming, D. W.
Gruener, J. E.
Date Acquired
August 21, 2013
Publication Date
October 1, 2003
Publication Information
Publication: Plant and soil
Volume: 256
Issue: 2
ISSN: 0032-079X
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: NGT9-34
Distribution Limits
Public
Copyright
Other
Keywords
NASA Discipline Life Support Systems
NASA Center JSC
Non-NASA Center

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