DNDC and Its Applications DNDC stands for D e n itrification and D e c omposition, two processes dominating loss of N and C from soil into the atmosphere, Changsheng Li respectively. Institute for the Study of Earth, Oceans and Space University of New Hampshire Biogeochemical Model is a Mathematical Expression of Biogeochemical Field The DNDC model is a result of Biochemical & Environmental Ecological geochemical factors drivers more than 10-year international reactions Mechanical movement Gravity efforts with researchers from the Dissolution / crystallization Radiation Climate Transformation Combination / decomposition Temperature U.S., China, Germany, the U.K., Soil properties & transport of chemical Oxidation / reduction Moisture Vegetation elements Eh Canada, Australia, New Zealand, Adsorption / desorption Anthropogenic activities pH Complexation / decomplexation Substrates the Netherlands, and Japan. Assimilation / dissimilation The DNDC Model Input Parameters ecological Climate Soil Vegetation Human activity drivers 1. Climate: - Daily air temperature and precipitation; water demand daily growth annual litter - Solar radiation; average water uptake potential temp. N-demand CO 2 very labile labile resistant - Atmospheric N deposition; evapotrans. microbes LAI-regulated water stress N-uptake grain albedo + evap. trans. NH 4 labile resistant vertical water stems 2. Soil: - Bulk density; soil temp humads flow root respiration profile labile resistant roots DOC - Texture (clay fraction); Plant growth soil moist O 2 soil Eh O 2 use profile diffusion profile - Total organic C content; passive humus Soil climate Decomposition effect of temperature and moisture on decomposition - pH; soil Temperature Moisture pH Eh Substrates: NH 4 + , NO 3 - , DOC environmental 3. Management:- Crop type and rotation; factors - Tillage; - Irrigation; NO 2 - NH 4 + CH 4 NO nitrate DOC nitrifiers CH 4 production DOC soil Eh - Fertilization; denitrifier NO 3 - NH 3 clay- - Manure amendment; N 2 O nitrite aerenchyma CH 4 oxidation + NH 4 denitrifier - NO 3 - Grazing . N 2 O NO N 2 NH 3 DOC N 2 O CH 4 transport Denitrification denitrifier Nitrification Fermentation 1
Biogeochemical Model Predicts Impacts of Alternative Management on Crop Yield and Environmental Safety Output INPUT INPUT INPUT PROCESSES OUTPUT 1. Crop: - Photosynthesis; Climate - Respiration; - Temperature Used by Emissions of - Water and N demands/uptake; - Precipitation soil N2O, NO, N2, - N deposition - Biomass allocation; microbes CH4 and CO2 - Yield and litter production; Soil properties Model - Texture - Organic matter tracking Dynamics - Bulk density 2. Soil: - Temperature, moisture, pH and Eh profiles; fundamental of soil water, - pH biochemical Competition NH4, NO3, N leaching - SOC dynamics; & and DOC geochemical - N leaching; processes Management - Emissions of N 2 O, NO, N 2 , NH 3 , CH 4 and CO 2 - Crop rotation - Tillage Used by Growth of crop - Fertilization plants biomass - Manure use - Irrigation - Grazing Comparison on CO2 emissions from a silty loam soil in a tilled and fertilized witer wheat field in Columbia, Missouri 40 Tillage Winter wheat field CO2 emission rate, kg C/ha/day 30 Model Validation 20 10 0 30 60 90 120 150 180 210 240 270 300 330 360 Julian day Simulated root respiration Simulated total CO2 Measured CO2 2
Two N2O peaks were caused by fertilization and rainfalls at a grassland in England Lianshui, Jiangsu, China, 1983-1992 0.008 DNDC captured long-term (Field data from Ryden 1983) 0.006 N2O + N2 Fluxes from a Grassland at Berkshire, England, May 28-June 28, 1981 0.004 SOC dynamics observed at 0.002 700 0 four crop fields in China 1 2 3 4 5 6 7 8 9 1 0 Year 600 500 - Lianshui, Jiangsu y a /d Yucheng, Shandong, China, 1986-94 /h a N 400 0.008 , g Field x 0.006 u Model fl 2 N 300 + 0.004 - Yucheng, Shandong O 2 N 0.002 200 0 1 2 3 4 5 6 7 8 9 1 0 100 Year - Pingliang, Gansu 0 7 9 1 3 5 7 9 1 3 5 7 9 1 3 5 7 4 1 1 4 1 5 1 5 1 5 1 5 1 5 1 6 1 6 1 6 1 6 6 1 1 7 1 7 1 7 1 7 Day Pingliang, Gansu, China, 1979-86 - Yueyiang, Hunan 0.008 Dynamics of Several Soil Environmental Factors at a Grassland 0.006 in Berkshire, England, May 28-June 28, 1981 0.004 0.002 120 12 0 1 2 3 4 5 6 7 8 Year 100 10 ) a /h F N 80 8 V N g , A k NH4+ ( ) - a Yueyang, Hunan, China, 1986-90 3 O /h NO3- 60 6 C N 0.03 g DOC d k n a C ( Eh O 0.02 + $ 40 4 D H N 0.01 20 2 0 1 2 3 4 5 6 Year 0 0 4 8 5 0 5 2 5 4 5 6 5 8 6 0 6 2 6 4 6 6 6 8 7 0 7 2 7 4 7 6 7 8 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 Day 3
10 Low N2O fluxes were 90 8 measured at a grassland in Two high peaks of N2O 80 N2O flux, g N/ha/day N2O flux, g N/ha/day 70 Colorado. Both nitrate and flux were caused by 6 60 DOC were limiting factors. 50 fertilization at a corn field 4 40 30 in Costa Rica, 1994. (Field data from Mosier et al., 20 2 1996) 10 (Field data from Crill et al., 0 314 320 326 332 338 344 350 356 362 3 9 15 21 27 33 39 45 51 57 63 69 0 1999) 1 20 39 58 77 96 115 134 153 172 191 210 229 248 267 286 305 324 343 362 Day -2 Field KC3 Field KC4 Model Day Field Model 5 25 Eh or Substrate (kg N or C/ha) 4 20 3 15 10 2 5 1 0 314 320 326 332 338 344 350 356 362 3 9 15 21 27 33 39 45 51 57 63 69 0 Day 1 19 37 55 73 91 109 127 145 163 181 199 217 235 253 271 289 307 325 343 361 NH4+ NO3- DOC ANVF X 10 Day NH4+ NO3- DOC ANVF Comparison of Measured and Modeled N 2 O Fluxes from 8 Agricultural N2O Fluxes from a Organic Soil at Glades, Florida, 1979-80 Sites In the U.S., China, Germany, and Costa Rica 5000 4500 1000 4000 Florida, unfertilized 3500 100 M o de le d N2O e mission, kg N/ha/yr N2O flux, g N/ha/day 3000 Jiangsu, Germany, fertilized fertilized 2500 10 2000 Costa Rica, Costa Rica, Beijing, unfertilized fertilized 1 fertilized 1500 Beijing, 0.01 0.1 1 10 100 1000 unfertilized 1000 Colorado, unfertilized 0.1 500 0 106 123 140 157 174 191 208 225 242 259 276 293 310 327 344 361 13 30 47 64 81 98 115 132 149 166 183 200 217 234 251 268 285 302 319 336 353 0.01 Day Observed N2O emission, kg N/ha/yr Field Model N 2 O and NO from Forests: Comparisons between observed and modeled fluxes from 28 forest stands in Europe and the U.S. (from dissertation of Florian Stange, Fraunhofer Institute for Atmospheric Environmental Studies, Garmisch- Patenkerchin, Germany, 2000) 4
Application 1: Predicting mitigation options 5
Application 2: Regional Inventory U.S. agricultural land emitted 876 Tg CO 2 -C in 1990 U.S. agricultural land received 1153 Tg residue-C in 1990 DNDC-Modeled C Storage in and Fluxes U.S. Agricultural Land gained 460 Tg SOC in 1990 from Agricultural Land in the U.S. in C storage in cropland, 1990 1990 Cropland Grassland and pasture Acreage (million ha) 141.2 204.5 C storage in 0-30 cm 7898.8 4155.7 (Tg C) Incorporated plant 331.7 821.4 residue (Tg C) Manure amendment 81.0 76.5 C storage in grassland and pasture, 1990 (Tg C) CO2 emission (Tg C) 446.8 428.7 CH4 emission (Tg C) 0.05 -0.03 DOC leaching (Tg C) 7.9 2.4 SOC change (Tg C) -7.0 466.9 6
http://www.dndc.sr.unh.edu 7
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