Discerning agricultural management effects on nitrous oxide emissions from conventional and alternative cropping systems: A California case study

Authors: SUDDICK, EMMA - University Of California; Steenwerth, Kerri; GARLAND, GINA - University Of California; SMART, DAVID - University Of California; SIX, JOHAN - University Of California

Submitted to: Journal of the American Chemical Society
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/12/2012
Publication Date: 10/12/2012
Citation: Suddick, E.C., Steenwerth, K.L., Garland, G.M., Smart, D., Six, J. 2012. Discerning agricultural management effects on nitrous oxide emissions from conventional and alternative cropping systems: A California case study. Journal of the American Chemical Society. DOI: 10.1021/bk-2011-1073.ch012.

Interpretive Summary: Several decades of research have provided crucial understanding of the production of nitrous oxide (N2O) from agricultural soils and the major environmental and managerial factors that play a role in the evolution of this potent greenhouse gas (GHG). The increase in demands for food production and the concomitant increases in use of N fertilizers to meet this demand, it is becoming more important to quantify the effects of the different factors contributing to N2O emissions and produce detailed, accurate and reliable annual N2O emission budgets for different agricultural systems. Within the diverse cropping regions of California, annual budgets are missing or incomplete for some of the state’s more important, high acreage cash crops such as grape and nut crops. Recent research documented within this paper highlights the difference in N2O emissions between conventional and alternative management practices in perennial cropping systems of California. Standard tillage (ST) had lower but not statistically significant N2O emissions compared to no tillage (NT) practices in a Northern California vineyard, where cumulative emissions were 0.19 ± 0.017 kg N2O-N ha-1 from the NT system as compared to 0.13 ± 0.021 kg N2O-N ha-1in the ST system. Our data highlights that there are large differences between standard and conservation irrigation techniques used and their effect on N2O emissions from a Northern California almond orchard, where following a four day fertigation event, sub-surface drip irrigation had lower emissions of N2O compared to surface drip, 0.006± 0.001 kg N2O-N ha-1 and 0.8 ± 0.021 kg N2O-N ha-1, respectively. We also show that the use of pyrolyzed agricultural wastes (biochar) as a soil amendment has the ability to reduce N2O emissions associated with fertigation peaks by approximately 41 %. Finally, we recommend based on our studies that future investigations in California should include longer term and more robust sampling to be able to create more accurate future emissions budgets and mitigate GHG emissions from perennial crops.

Technical Abstract: Several decades of research have provided crucial understanding of the production of nitrous oxide (N2O) from agricultural soils and the major environmental and managerial factors that play a role in the evolution of this potent greenhouse gas (GHG). The increase in demands for food production and the concomitant increases in use of N fertilizers to meet this demand, it is becoming more important to quantify the effects of the different factors contributing to N2O emissions and produce detailed, accurate and reliable annual N2O emission budgets for different agricultural systems. Within the diverse cropping regions of California, annual budgets are missing or incomplete for some of the state’s more important, high acreage cash crops such as grape and nut crops. Recent research documented within this paper highlights the difference in N2O emissions between conventional and alternative management practices in perennial cropping systems of California. Standard tillage (ST) had lower but not statistically significant N2O emissions compared to no tillage (NT) practices in a Northern California vineyard, where cumulative emissions were 0.19 ± 0.017 kg N2O-N ha-1 from the NT system as compared to 0.13 ± 0.021 kg N2O-N ha-1in the ST system. Our data highlights that there are large differences between standard and conservation irrigation techniques used and their effect on N2O emissions from a Northern California almond orchard, where following a four day fertigation event, sub-surface drip irrigation had lower emissions of N2O compared to surface drip, 0.006± 0.001 kg N2O-N ha-1 and 0.8 ± 0.021 kg N2O-N ha-1, respectively. We also show that the use of pyrolyzed agricultural wastes (biochar) as a soil amendment has the ability to reduce N2O emissions associated with fertigation peaks by approximately 41 %. Finally, we recommend based on our studies that future investigations in California should include longer term and more robust sampling to be able to create more accurate future emissions budgets and mitigate GHG emissions from perennial crops.