ARS | Publication request: EFFECTS OF SOIL MOISTURE, PHYSICAL, AND CHEMICAL CHARACTERISTICS ON ABIOTIC NITRIC OXIDE PRODUCTION

Submitted to: Nutrient Cycling in Agroecosystems
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: August 4, 2004
Publication Date: May 1, 2005
Repository URL: http://hdl.handle.net/10113/22279
Citation: Venterea, R.T., Rolston, D.E., Cardon, Z. 2005. Effects of soil moisture, physical, and chemical characteristics on abiotic nitric oxide production. Nutrient Cycling in Agroecosystems. 72:27-40.

Interpretive Summary: The production of nitric oxide (NO) in agricultural soils can lead to off-site losses of fertilizer N in gaseous form which can have subsequent impacts on the local formation of ozone (O3) in the lower atmosphere. Crop damage due to the phytotoxic effects of O3 is estimated at $2 billion per year in the U.S. The objective of this study was to examine controls over the abiotic production of nitric oxide (NO) in agricultural soils from eight different fields in Minnesota, California, and Connecticut, USA. The major finding was that abiotic NO production decreased with increasing soil water content in all the soils examined. We also found that NO production was positively correlated with soil total carbon and nitrogen contents, levels of extractable iron, and clay and silt content, and negatively correlated with the ratio of cation exchange capacity:clay fraction. Multiple regression models incorporating two, three, and four parameters, were able to explain 87, 89, and 90% of the total variance in NO production, respectively. We also used the obtained relationships in a previously developed model in order to examine the overall sensitivity of net soil-to-atmosphere emissions of NO to varying soil water content. While managing soil water content has always been important in agricultural soils, these data present some new consequences of this management with respect to minimizing NO emissions and possibly controlling the impacts of soil NO emissions on local O3 formation. The data presented here will aid soil scientists in better understanding nitrogen dynamics in fertilized soils. In addition, this type of information will be useful to policy makers attempting to develop strategies for mitigating the overall environmental impacts of intensive nitrogen fertilizer use.

Technical Abstract: The objective of this study was to examine empirical controls over nitrous acid (HNO2)-mediated abiotic production of nitric oxide (NO) in agricultural soils from eight different fields in Minnesota, California, and Connecticut, USA. We determined the rate-coefficient (kp) describing HNO2-mediated NO production in gamma-irradiated soils and measured a range of soil physical and chemical characteristics. The major finding was that kp decreased with increasing gravimetric soil water content in all the soils examined. We also found that kp was positively correlated with soil total carbon and nitrogen contents, levels of extractable iron, and clay and silt content, and negatively correlated with the ratio of cation exchange capacity:clay fraction. Multiple regression models incorporating two, three, and four parameters, were able to explain 87, 89, and 90% of the total variance in kp, respectively. We also used the obtained relationships between kp and soil water content in a previously developed model describing NO production, transformation, and diffusive transport in order to examine the overall sensitivity of net soil-to-atmosphere emissions of NO to varying soil water content.