Nitrous Oxide Emission in Relation to Soil Factors at Low to Intermediate Moisture Levels
1994
Robertson, Kerstin
The objective of this study was to investigate the N₂O emission from agricultural soils (14 field plots/38 measurements) as a function of environmental and soil factors-clay content, soil temperature, soil moisture, total organic C and N, water-soluble organic C, nitrate and ammonium concentrations, and pH-that are considered of significance for N₂O production in soil. Passible relations were tested by multiple linear regression and multivariate data analysis (PLS). A significant (P ≤ 0.05) relation (linear regression) was obtained only between N₂O emission rates and NO⁻₃ concentration in soil. However, the degree of explanation was low (R² = 13%). If one field, with N₂O emission rate several orders of magnitude higher than from the others, was excluded from the analysis a significant relation with the NH⁺₄ concentration was obtained. In this case the degree of explanation was 17%. The results from the PLS analysis were similar to those from the regression analysis. If clay soils (>40% clay) were analyzed separately, NH⁺₄ concentration and soil moisture accounted for 65% (P < 0.05) of the variability of the N₂O emission rates. In the medium- and low-clay soils no similar relationships were found. In conclusion, the obstacles caused by the complexity of the soil system and the different scales of measurement of N₂O emission rates and soil factors probably obscured the possibility to relate the N₂O emission rates to single or combinations of soil factors.
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