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United States Department of Agriculture

Agricultural Research Service

Title: Nitrous Oxide Emissions from a Wheat-Soybean Relay Intercrop

Authors
item Tubbs, Ronald
item Schepers, James

Submitted to: Agronomy Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: August 1, 2005
Publication Date: November 1, 2005
Citation: Tubbs, R.S., Schepers, J.S. 2005. Nitrous oxide emissions from a wheat-soybean relay intercrop. Agronomy Abstracts.

Technical Abstract: Agricultural activities are the leading source of nitrous oxide (N2O) emissions, coming mainly from N fertilizers. This experiment took place in Shelton, Nebraska to evaluate soil emissions of N2O from a relay intercrop of wheat (Triticum aestivum L.) with soybean [Glycine max (L.) Merr] compared to growing either crop alone. Samples were taken on 22 June and 1 July 2005. On 22 June, immediately following a rainfall event, N2O-N flux was 14.7 g ha-1 d-1 from bare soil, 13.9 g ha-1 d-1 from wheat alone, 13.5 g ha-1 d-1 from soybean alone, and 21.7 g ha-1 d-1 from the relay intercrop of wheat and soybean. On 1 July, immediately before a rainfall event, N2O-N flux was 2.1 g ha-1 d-1 from bare soil, 1.7 g ha-1 d-1 from wheat alone, 1.8 g ha-1 d-1 from soybean alone, and 1.0 g ha-1 d-1 from the relay intercrop of wheat and soybean. In wet conditions, N2O emissions are much higher than in dry conditions. The relay crop system had lowest emissions in dry conditions and highest emissions in wet conditions. When soils are saturated beyond field capacity, plants emit N2O, which would account for the highest emissions in the relay crop system after rainfall, since more plants are present in that system. In non-saturated conditions, this data shows that a relay intercrop of wheat with soybean emits less N2O than either crop alone, most likely due to more efficient uptake of N fertilizer by the system.

Last Modified: 4/15/2014
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