Phytotron Experiments to Evaluate the Effect of Growing Plants on Denitrification
1985
Haider, K. | Mosier, A. | Heinemeyer, O.
The amount and availability of plant rhizosphere carbon deposits and their influence on microbial denitrification in soil are not clearly defined. To evaluate this possibly important facet of fertilizer N loss from agricultural soils a study was conducted to simultaneously quantify the carbon fixed by plants and the fate of fertilizer nitrogen applied to the soil during a plant growing season. Corn (Zea mays) or wheat (Triticum aestivum) was grown in a phytotron under a continuous supply of ¹⁴CO₂ in ¹⁵N fertilized soil. The results of the studies show that denitrification was not stimulated in soils planted with corn or wheat compared to unplanted soil. About 60% of the root biomass carbon could be found in the soil as rhizodeposited carbon at the termination of the experiments. Only 5 to 7% of this carbon was, however, extractable with water or 2 M Na₂SO₄. This suggests that even though a sufficient quantity of carbon was deposited in the soil by the plants that the carbon was not available for denitrification.
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