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Microbial responses and nitrous oxide emissions during wetting and drying of organically and conventionally managed soil under tomatoes

Biology and Fertility of Soils

By:
, , , , , , and
DOI: 10.1007/s00374-005-0007-z

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Abstract

The types and amounts of carbon (C) and nitrogen (N) inputs, as well as irrigation management are likely to influence gaseous emissions and microbial ecology of agricultural soil. Carbon dioxide (CO2) and nitrous oxide (N2O) efflux, with and without acetylene inhibition, inorganic N, and microbial biomass C were measured after irrigation or simulated rainfall in two agricultural fields under tomatoes (Lycopersicon esculentum). The two fields, located in the California Central Valley, had either a history of high organic matter (OM) inputs ("organic" management) or one of low OM and inorganic fertilizer inputs ("conventional" management). In microcosms, where short-term microbial responses to wetting and drying were studied, the highest CO2 efflux took place at about 60% water-filled pore space (WFPS). At this moisture level, phospholipid fatty acids (PLFA) indicative of microbial nutrient availability were elevated and a PLFA stress indicator was depressed, suggesting peak microbial activity. The highest N 2O efflux in the organically managed soil (0.94 mg N2O-N m-2 h-1) occurred after manure and legume cover crop incorporation, and in the conventionally managed soil (2.12 mg N2O-N m-2 h-1) after inorganic N fertilizer inputs. Elevated N2O emissions occurred at a WFPS >60% and lasted <2 days after wetting, probably because the top layer (0-150 mm) of this silt loam soil dried quickly. Therefore, in these cropping systems, irrigation management might control the duration of elevated N2O efflux, even when C and inorganic N availability are high, whereas inorganic N concentrations should be kept low during times when soil moisture cannot be controlled.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
Microbial responses and nitrous oxide emissions during wetting and drying of organically and conventionally managed soil under tomatoes
Series title:
Biology and Fertility of Soils
DOI:
10.1007/s00374-005-0007-z
Volume
42
Issue:
2
Year Published:
2005
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
Larger Work Title:
Biology and Fertility of Soils
First page:
109
Last page:
118