Denitrification activity in the root zone of a sludge-amended desert soil

Janick F. Artiola, Ian L. Pepper

Research output: Contribution to journalArticlepeer-review


We evaluated potential NOinf3sup-losses from organic and inorganic N sources applied to improve the growth of cotton (Gossypium hirsutum) on a Pima clay loam soil (Typic Torrifluvent). An initial set of soil cores (April 1989) was collected to a depth of 270 cm from sites in a cotton field previously amended with anaerobically digested sewage sludge or an inorganic N fertilizer. The denitrification potential was estimated in all soil samples by measuring N2O with gas chromatography. Soils amended with a low or high rate of sludge showed increased denitrification activity over soil samples amended with a low rate or inorganic N fertilizer. All amended samples showed greater denitrification activity than control soils. The denitrification decreased with soil depth in all treatments, and was only evident as deep as 90 cm in the soils treated with the high sludge rate. However, when soils collected from depths greater than 90 cm were amended with a C substrate, significant denitrification activity occurred. These date imply that organisms capable of denitrification were present in all soil samples, even those at depths far beneath the root zone. Hence, denitrification was C-substrate limited. A second series of soil cores taken later in the growing season (July 1989) confirmed these data. Denitrification losses (under laboratory conditions) to a soil depth of 270 cm represented 1-4% of total soil N depending on treatment, when the activity was C-substrate limited. With additional C substrate, the denitrification losses increased to 15-22% of the total soil N.

Original languageEnglish (US)
Pages (from-to)200-205
Number of pages6
JournalBiology and Fertility of Soils
Issue number4
StatePublished - Aug 1992


  • Anaerobically digested sludge
  • Cotton
  • Denitrification
  • Desert soil
  • Furrow irrigation

ASJC Scopus subject areas

  • Microbiology
  • Agronomy and Crop Science
  • Soil Science


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