ISSN:
1365-2389
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
,
Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
Notes:
Existing mechanistic models of denitrification in clods of soil describe the anaerobic activity in the centres of the clods, but they neglect the role of particulate organic materials. We therefore studied the effect of particulate organic matter on denitrification in soil both under pasture and in arable cultivation. Clods were separated into two compartments: (i) particulate organic matter and adhering soil exceeding 200 μm (coated POM), and (ii) the matrix (the rest of the soil). Potential denitrification and production of CO2 were then estimated on coated POM, matrix and unfractionated soil. The quantity and the quality of coated POM were assessed individually in 100 clods from the pasture and 100 from the arable land. The rate of potential denitrification was similar in unfractionated soil from these treatments. However, it was 70 times greater in the coated POM than in the matrix from the arable soil. Production of CO2 was nine times greater in the coated POM than in the matrix from the pasture soil and 33 times greater in the arable soils. These observations were the basis for a mechanistic model of denitrification, taking into account contributions from coated POM and the matrix. Denitrification rates in a computerized representation of clods from both pasture and arable soil had approximately the same distribution as experimental data both in the matrix and coated POM contributions in the cropped soil and in the matrix alone in the pasture soil. Coated particulate organic matter can explain more than half of the denitrification and most of the variation in denitrification when it increases microbial activity sufficiently and the soil structure limits the supply of O2.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1046/j.1365-2389.2000.00298.x
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