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Soil Respiration as an Index of Soil Aeration
Author(s) -
Neilson J. W.,
Pepper I. L.
Publication year - 1990
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1990.03615995005400020022x
Subject(s) - loam , aeration , bulk density , soil respiration , soil water , environmental science , water content , agronomy , chemistry , soil test , calcareous , fertilizer , soil science , environmental chemistry , botany , geology , biology , geotechnical engineering , organic chemistry
The accurate determination of available soil O 2 is problematic due to the dynamic interaction of physical and biological soil properties. This study was conducted to evaluate combined effects of soil bulk density, water content, and organic and inorganic amendments on available soil O 2 , using CO 2 evolution from soil respiration as an index. Optimal levels of soil aeration vary with respiratory O 2 consumption, which is influenced by soil amendments. Comparisons were made between Pima clay loam [fine‐silty, mixed (calcareous), thermic, Typic Torrifluvent] amended with inorganic fertilizer or anaerobically digested liquid sewage sludge at equivalent N loading rates. Pima soil was amended with inorganic fertilizer, artificially compacted to bulk densities of 1.1, 1.4, and 1.6 Mg m −3 and maintained at gravimetric water contents of 0.10, 0.20, and 0.24 kg kg −1 . Soil samples were placed in air‐tight mason jars fitted with rubber serum stoppers for gas sampling. Carbon dioxide evolution from microbial respiration was monitored for an incubation period of 18 to 26 d. Aeration became limiting to microbial respiration at a bulk density of 1.6 Mg m −3 and 0.24 kg kg −1 water content (97% saturation). In sewage‐sludge‐amended soil compacted to a bulk density of 1.4 Mg m −3 and maintained at a range of water contents from 0.09 to 0.30 kg kg −1 , aeration became limiting to microbial respiration at a water content of 0.26 kg kg −1 (77% saturation). These data illustrate the limitation of using percent saturation or water‐filled pore space as an index characterizing soil aeration, particularly when soils of differing bulk densities are compared. Respiration rates in the inorganic‐fertilizer‐ and sludge‐amended soil samples were equivalent.