Effect of water-filled pore space on carbon dioxide and nitrous oxide production in tilled and nontilled soils [Maize; Illinois; Kentucky; Minnesota; Nebraska]

• Published in: Soil Science Society of America journal Vol. 48; no. 6; pp. 1267 - 1272
• Main Authors: Linn, D.M, Doran, J.W
• Format: Journal Article
• Language: English
• Published: Madison, WI Soil Science Society of America 01-11-1984
• Subjects: Agronomy. Soil science and plant productions; Animal, plant and microbial ecology; Biological and medical sciences; CARBON DIOXIDE; Chemical, physicochemical, biochemical and biological properties; CLAY LOAM SOILS; Fundamental and applied biological sciences. Psychology; ILLINOIS; KENTUCKY; LOAM SOILS; MAIZE; MICROBIAL ACTIVITIES; Microbial ecology; MINNESOTA; NEBRASKA; NITROUS OXIDE; NO-TILLAGE; Organic matter; Physics, chemistry, biochemistry and biology of agricultural and forest soils; SILTY SOILS; Soil; Soil science; SOIL WATER CONTENT; TILLAGE; Microbial activity; Aerobiosis; Soil tillage; Carbon dioxide; Microflora; Soil air; Aeration; Nitrification; Denitrification; Soil; Porosity; Nitrogen protoxide; Respiration
• ISSN: 0361-5995; 1435-0661
• DOI: 10.2136/sssaj1984.03615995004800060013x

The percentage of soil pore space filled with water (percent water‐filled pores, % WFP), as determined by water content and total porosity, appears to be closely related to soil microbial activity under different tillage regimes. Soil incubated in the laboratory at 60% WFP supported maximum aerobic microbial activity as determined by CO2 production and O2 uptake. In the field, % WFP of surface no‐tillage soils (0–75 mm) at four U.S. locations averaged 62% at time of sampling, whereas that for plowed soils was 44%. This difference in % WFP was reflected in 3.4 and 9.4 times greater CO2 and N2O production, respectively, from surface no‐tillage soils over a 24‐h period as compared to plowed soils. At a depth of 75 to 150 mm, % WFP values increased in both no‐tillage and plowed soils, averaging approximately 70% for no tillage compared with 50 to 60% for plowed soils. Production of CO2 in the plowed soils was enhanced by the increased % WFP, resulting in little or no difference in CO2 production between tillage treatments. Nitrous oxide production, however, remained greater under no‐tillage conditions. Substantially greater amounts of N2O were produced from the N‐fertilized soils, regardless of tillage practice. Production of CO2 and N2O was primarily related to the % WFP of tillage treatments although, in several instances, soil‐water‐soluble C and NO‐3 levels were important as well. Calculations of relative aerobic microbial activity between no‐tillage and plowed soils, based on differences in % WFP relative to maximum activity at 60%, indicated linear relationships for CO2 and N2O production between WFP values of 30 to 70%. Below 60% WFP, water limits microbial activity, but above 60%, aerobic microbial activity decreases—apparently the result of reduced aeration.