Scientific status on nitrous oxide emissions from agricultural systems Johan Six
Management changes (regional) Tillage Fertilizer Cover crop GWP ΔSOC N 2 O (Mg CO 2 -eq ha -1 yr -1 ) (kg C ha -1 yr -1 ) (kg N ha -1 yr -1 ) Sacramento Valley convent. mineral, 75% no -.89 ±.76-2 ± 16-1.92 ± 1.59 conserv. mineral no -.68 ±.36 13 ± 34 -.64 ±.56 convent. mineral yes -1.36 ±.89 31 ± 18 -.48 ±.94 conserv. mineral yes -1.37 ±.88 312 ± 178 -.48 ±.94 convent. Organic no -1.16 ±.78 158 ± 63-1.23 ± 1.51 conserv. Organic no -1.94 ± 1.3 288 ± 88-1.89 ± 1.86 convent. Organic yes -2.6 ± 1.87 45 ± 212-2.38 ± 2.81 conserv. Organic yes -3.29 ± 2.7 532 ± 246-2.86 ± 2.98 San Joaquin Valley convent. mineral, 75% no -.61 ±.58-4 ± 14-1.33 ± 1.24 conserv. mineral no -.57 ±.33 81 ± 35 -.59 ±.55 convent. mineral yes -1.35 ± 1.7 284 ± 17 -.66 ± 1.36 conserv. mineral yes -1.38 ± 1.8 287 ± 169 -.68 ± 1.39 convent. Organic no -.49 ±.89 154 ± 54.16 ± 1.96 conserv. Organic no -1.14 ±.9 255 ± 79 -.43 ± 1.82 convent. Organic yes -1.87 ± 1.41 395 ± 23 -.89 ± 2.41 conserv. Organic yes -2.45 ± 1.52 498 ± 235-1.32 ± 2.41 De Gryze et al 211 AGEE
Status of N 2 O budgets (29) cropping system nr observations in literature alfalfa 4 nut orchards vineyards cotton 5 rice 78 intensely cropped vegetables 29 wheat 77 fruit orchards tomato 6 corn 157 3 in progress 3 published 3 in progress
N2O emission (g N2O-N ha -1 day -1 ) rainfall (mm day -1 ) N 2 O: variability! 25 2 2 winter tomato growing season fall 4 6 15 post spring tillage dry post-harvest 8 1 1 N applications 12 spring tillage fall tillages 14 5 16 18 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec time
N2O emission (g N2O-N ha -1 day -1 ) rainfall (mm day -1 ) N 2 O: targeted measures 25 2 2 winter tomato growing season fall 4 6 15 post spring tillage dry post-harvest 8 1 1 N applications 12 spring tillage fall tillages 14 5 16 18 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec time
Almond orchard Tree Row
Cumulative seasonal N 2 O emissions.6.5 kg N 2 O-N ha -1 season -1.4.3.2.1. Tree Row Garland et al In prep
Cumulative & weighted N 2 O emissions.5.4 kg N 2 O-N ha -1 yr -1.3.2.1. Garland et al In prep
Fertigation event N 2 O emissions.12.1 Surface Drip Microsprinkler Sub-surface Drip kg N 2 O-N ha -1.8.6.4.2. Treatments Suddick et al 211
Cumulative annual N 2 O emissions (Tomato) Kennedy et al in prep
Management Fertilizer Type Tomato Cultivar kg N ha -1 applied Yield (ton acre -1 ) Conventional Integrated CAN17 UN32 AB2 AB2 19 25 35 53 Kennedy et al in prep
Biochar
Cumulative N 2 O emissions (Walnut).25 Walnut Orchard Tree Row Cumulative N 2 O (Kg N 2 O-N ha -1 season -1 ).2.15.1.5. control compost biochar biochar + compost Apr Jun Aug Oct Dec Sampling Date (21).8 Walnut Orchard Tractor Row Cumulative N 2 O (Kg N 2 O-N ha -1 season -1 ).6.4.2. Apr Jun Aug Oct Dec Sampling Date (21) Suddick et al In prep
Cumulative N 2 O emissions (Lettuce) Cumulative N2O (kg N2O-N ha -1 ).25.2.15.1.5. -.5 Control Compost Biochar + Compost Biochar 27 28 29 3 31 Julian Day Suddick et al In prep
Vineyard Vine Row
Cumulative annual N 2 O emissions 2.5 2. kg N 2 O-N ha -1 yr -1 1.5 1..5. Year 1 Year 2 Garland et al In prep
Conclusions N 2 O emissions are significant in agriculture BUT, there are options to reduce it AND not only through reducing fertilizer use and impacting yields SO, simple emission factors do not work!
Eddy covariance (TDL / QCL) N 2 O flux footprint
N2O emission (g N2O-N ha -1 day -1 ) rainfall (mm day -1 ) Modeling! 25 2 2 winter tomato growing season fall 4 6 15 post spring tillage dry post-harvest 8 1 1 N applications 12 spring tillage fall tillages 14 5 16 18 2 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec time
Acknowledgements Emma Suddick Gina Garland Taryn Kennedy Bob Rousseau Steven De Gryze California Energy Commission Packard Foundation Thank you!
Cumulative seasonal N 2 O emissions 3.5 3. kg N 2 O-N ha -1 season -1 2.5 2. 1.5 1..5. Vine Row Garland et al In prep
N 2 O emissions Steenwerth & Belina 21 AGEE
Tree N 2 O g N 2 O-N ha -1 day -1 5 4 3 2 1 fertilization precipitation 8 7 6 WFPS % WFPS 5 4 3 2 1 8 NO 3 ug NO 3 -N g -1 soil 6 4 2 25 NH 4 ug NH 4 -N g -1 soil 2 15 1 5 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Date Garland et al In prep
N 2 O g N 2 O-N ha -1 day -1 5 4 3 2 1 Row fertilization fertilization precipitation 8 7 WFPS % WFPS 6 5 4 3 2 1 8 NO 3 ug NO 3 -N g -1 soil 6 4 2 8 NH 4 ug NH 4 -N g -1 soil 6 4 2 Mar Apr May Jun Jul Aug Sep Oct Nov Dec Jan Feb Mar Date Garland et al In prep
CT Vine CT Row.14.2 kg N 2 O-N ha -1 hr -1.12.1.8.6.4.2 fertilization kg N 2 O-N ha -1 hr -1.15.1.5 Cover crop incorporation precipitation.. -.2 -.4 Mar Apr May Jun Jul Aug Sep Oct Date -.5 Mar Apr May Jun Jul Aug Sep Oct Date NT Vine NT Row.7.6 fertilization.6.5 Cover crop mow kg N 2 O-N ha -1 hr-1.5.4.3.2.1 kg N 2 O-N ha -1 hr -1.4.3.2.1 precipitation.. -.1 Mar Apr May Jun Jul Aug Sep Oct Date -.1 Mar Apr May Jun Jul Aug Sep Oct Date Garland et al 211 AGEE
Lettuce biochar experiment Head Lettuce : Environmentally sensitive 1m by 1m plots 4 treatments with 5 replicates Fertilizer added to all plots : 12 kg N/ha Treatments Control (only fertilizer added) Biochar (5 t/ha) Compost (5 t/ha) Biochar + Compost (2.5 + 2.5 t/ha)
Lettuce Yield g fresh weight -1 16 14 12 1 8 6 4 Control Compost Biochar + Compost Biochar All treatments statistically the same yield = bio-char did NOT kill the lettuce! 2 Treatments