Supplemental Material to Accompany: Long-term Agro-ecosystem Research in the Central Mississippi River Basin, USA - SWAT Simulation of Flow and Water Quality in the Goodwater Creek Experimental Watershed Claire Baffaut 1, Fessehaie Ghidey 1, E. John Sadler 1, and Stephen H. Anderson 2 1 USDA-ARS Cropping Systems and Water Quality Research Unit 2 University of Missouri, Department of Soil, Environmental and Atmospheric Sciences Columbia, Missouri Contents S1. Field operation scenarios... 2 S2. Land use and land management distribution... 4 S3. SWAT sensitive parameters in GCEW... 5 S4. Simulated effects of operation scheduling... 6 S5. Simulated effectiveness of herbicide incorporation... 7 S6. Simulated effectiveness of reducing atrazine application rate... 8 S7. References... 8 Tables: Supplemental Table S1. Crop and tillage management for corn, grain sorghum, soybean, and winter wheat.... 2 Supplemental Table S2. Land use and land management distribution before and after Hydrologic Response Unit definition.... 4 Supplemental Table S3: SWAT model parameters identified as sensitive and adjusted during calibration.... 5 Supplemental Table S4. Effect of using planting progress reports on simulated annual atrazine and sediment export from GCEW.... 6 Supplemental Table S5. Effect of incorporation after application on simulated annual atrazine export from GCEW.... 7 Supplemental Table S6. Effect of atrazine application rates on simulated atrazine export from GCEW.... 8
S1. Field operation scenarios Field operation scenarios were derived from producer specific information obtained through surveys conducted in 1992 and 2007, along with information on agronomic rates of fertilizers corresponding to expected crop yields in the region and label rates for herbicides. Dates were initially defined. Heat unit indices are defined in two ways, depending upon the growing status of a crop. If a crop is not growing, the heat unit index is defined as the fraction of cumulative heat degree days since the beginning of the year by the average annual number of heat degree days, relative to a base temperature of 0 o C. If a crop is growing, the heat unit index is defined as the fraction of cumulative heat degree days since the beginning of the growing season by the total number of heat degree days needed to bring the plant to maturity, relative to the base temperature of the plant. Supplemental Table S1. Crop and tillage management for corn, grain sorghum, soybean, and winter wheat. Crop Type Management Date HUI 1 Corn Conventional Corn Conservation Corn no-till Sorghum Conventional Disking Injection of Anhydrous Ammonia) @ 130 kg ha -1 Spreading of Elemental Nitrogen @ 33.6 kg ha -1 Spreading of Elemental Phosphorous @ 24.3 kg ha -1 Field Cultivation Planting corn Atrazine broadcast spraying @ 2.25 kg ha -1 Harvest / Kill Generic Conservation Tillage Injection of Anhydrous Ammonia @ 130 kg ha -1 Spreading of Elemental Nitrogen @ 33.6 kg ha -1 Spreading of Elemental Phosphorous @ 39.4 kg ha -1 Generic Conservation Cultivation Planting corn Atrazine broadcast spraying @ 2.25 kg ha -1 Harvest / Kill Knifing of Anhydrous Ammonia @ 130 kg ha -1 Spreading of Elemental Nitrogen @ 33.6 kg ha -1 Spreading of Elemental Phosphorous @ 24.3 kg ha -1 Atrazine broadcast spraying @ 1.25 kg ha -1 No-till mixing Planting corn Atrazine broadcast spraying @ 1.25 kg ha -1 Harvest Disking Injection of Anhydrous Ammonia @ 130 kg ha -1 Spreading of Elemental Nitrogen @ 33.6 kg ha -1 Spreading of Elemental Phosphorous @ 39.4 kg ha -1 Field Cultivation Planting sorghum Atrazine broadcast spraying @ 2.25 kg ha -1 Harvest / Kill Nov 1 March 15 April 1 April 2 April 3 April 25 May 8 Oct 1 Nov 1 March 15 April 1 April 2 April3 April 25 May 8 Oct 1 March 25 April 8 April 9 April 10 April 11 May 5 May 16 Oct 10 Nov 1 March 15 April 1 April 2 April3 April 25 May 8 Oct 1 0.96 0.05 0.09 0.10 0.11 0.16 0.07 1.12 0.96 0.06 0.09 0.10 0.11 0.16 0.07 1.22 0.05 0.11 0.12 0.13 0.14 0.19 0.06 1.12 0.96 0.05 0.09 0.10 0.11 0.17 0.05 1.16 Soybean General Conservation Plowing Nov 1 0.95
Crop Type Management Date HUI 1 Conservation Spreading of Elemental Phosphorous @ 15.1 kg ha -1 Generic Conservation Cultivation Planting soybeans Harvest / Kill May 1 May 2 May 5 Oct 10 0.17 0.18 0.19 1.15 Soybean no-till Wheat no-till 1 Heat Unit Index Spreading of Elemental Phosphorous @ 15.1 kg ha -1 No-till incorporation Planting soybeans Harvest Spreading of Elemental Nitrogen @ 44.8 kg ha -1 Spreading of Elemental Phosphorous @ 30 kg ha -1 No-till incorporation Planting wheat Spreading of Elemental Nitrogen @ 67.2 kg ha -1 Harvest / Kill wheat Planting soybean Harvest / Kill soybean May 9 May 10 May 12 Oct 1 Oct 12 Oct 13 Oct 14 Oct 15 March 15 June 25 July 3 Oct 10 0.20 0.21 0.22 1.13 0.89 0.90 0.91 0.92 0.06 1.10 0.47 1.0
S2. Land use and land management distribution Supplemental Table S2. Land use and land management distribution before and after Hydrologic Response Unit definition. Land Use % of watershed area before HRU definition % of watershed area after HRU definition Residential 4.7 4.7 Corn Conventional 11.7 15.6 Corn Conservation 5.1 6.3 Corn No-till 3.5 4.7 Soybean Conventional 12.4 12.5 Soybean Conservation 8.8 8.6 Soybean No-till 26.3 26.6 Grain Sorghum Conventional 2.7 1.6 Wheat No-till 2.5 2.3 Woodland - Grazed 1.3 0.4 Woodland - Non grazed 6.1 2.2 Hay 3.9 4.0 Pasture 1 2.9 2.9 Pasture 2 2.9 2.9 CRP 4.7 4.8 Water 0.6 0.0
S3. SWAT sensitive parameters in GCEW Supplemental Table S3: SWAT model parameters identified as sensitive and adjusted during calibration. Model output Stream Flow Sediment Yield Atrazine Load P transport Parameter Definition Default Value Baseline Value Adjusted Value SFTMP Snow fall temperature 1.0 1.0 1.5 SMTMP Snow melt temperature 0.5 0.5-2.5 SMFMX Snow melt max rate 4.5 4.5 SMFMN Snow melt min rate 4.5 2.0 1.5 TIMP Snow pack temperature lag factor 1.0 1.0 SNOCOVMX Minimum snow water content for 100% snow cover 1.0 1.0 25.0 Fraction of snow volume represented by SNCSOCOV SNOCOVMX that corresponds to 50% snow cover 0.5 0.5 ESCO Soil evaporation compensation factor 0.95 0.95 0.90 EPCO Plant evaporation compensation factor 1.0 1.0 SURLAG Surface runoff lag coefficient 4.0 4.0 2.0 SHALLST Initial depth of water in the shallow aquifer 1000.0 1000.0 600.0 DEEPST Initial depth of water in the deep aquifer 2000.0 2000.0 1000.0 GW_DELAY Groundwater delay time 31.0 31.0 ALPHA_BF Baseflow alpha factor 0.048 0.048 0.4 GWQMN Shallow aquifer depth of water required for return 0.0 0.0 150.0 flow to occur GW_REVAP Groundwater revap coeffcient 0.020 0.020 0.045 REVAPMN Shallow aquifer depth of water required for revap 1.0 1.0 125.0 to occur RCHRG_DP Deep aquifer percolation fraction 0.05 0.05 USLE_P USLE support practice factor 1.0 1.0 0.70 USLE_K USLE erodibility factor 0.43 0.43 0.28 USLE_C Minimum value of USLE crop factor SWAT database Adjusted by tillage according to the values given by Alberts et al. (1985) CH_COV1 Channel erodibility factor 0.0 0.0 0.6 CH_COV2 Channel cover factor 0.0 0.0 0.6 ADJ_PKR Peak rate adjustment factor 0.0 0.0 0.9 PRF Peak rate adjustment factor for sediment routing 1.0 1.0 0.8 SPCON Linear parameter for channel sediment routing 0.0001 0.0001 0.0009 SPEXP Exponent parameter for channel sediment routing 1.0 1.0 1.25 HLIFE_S Atrazine half life 60.0 15.0 PERCOP Atrazine percolation coefficient 0.5 0.5 0.25 P_UPDIS Phosphorus uptake distribution parameter 20.0 20.0 60.0 PPERCO Phosphorus percolation coefficient 10.0 10.0 PSP Phosphorus sorption coefficient 0.4 0.4 0.69 PHOSKD Phosphorous soil partitioning coefficient 175.0 175.0 ERORGP Phosphorus enrichment ratio 0.0 0.0 3.5 BC4 Rate constant for mineralization of organic P to dissolved P in stream reach 0.35 0.35 0.08
S4. Simulated effects of operation scheduling The following table presents annual values of herbicide and sediment transport out of GCEW from 1993 to 2010. The coefficients of determination and slope of the regression between measured and simulated values are also presented. Supplemental Table S4. Effect of using planting progress reports on simulated annual atrazine and sediment export from GCEW. Annual Atrazine Loss, g ha -1 Sediment transport, kg ha -1 Year Measured With planting progress reports Without planting progress reports Measured With planting progress reports Without planting progress reports 1993 17.2 14.6 22.1 3083 2196 2148 1994 11.2 10.8 7.0 1550 1246 1313 1995 18.7 15.8 134.8 1227 1343 792 1996 10.8 11.7 23.5 466 293 423 1997 15.2 17.4 22.3 1089 1011 1086 1998 11.5 5.0 1.6 1255 1846 1538 1999 21.4 17.0 34.2 883 1300 1251 2000 1.5 2.0 1.8 34 56 53 2001 16.0 14.7 13.8 903 1450 1434 2002 22.3 19.6 36.9 1103 2929 3287 2003 11.6 5.4 2.4 1132 1492 1661 2004 4.3 7.5 11.1 1490 910 936 2005 3.2 2.0 1.7 1164 539 565 2006 10.7 10.9 7.7 371 660 664 2007 8.0 1.8 0.6 1361 742 616 2008 25.0 26.4 20.6 5713 3554 3362 2009 22.1 20.2 14.6 2834 1743 1706 2010 11.9 8.9 10.3 3170 1560 1616 Mean 13.5 11.7 20.4 1602 1382 1358 r 2, 0.84 0.19 0.55 0.47 Regression slope 0.94 1.96 0.49 0.46 : The coefficient of determination and the regression slopes are between the measured and simulated values.
S5. Simulated effectiveness of herbicide incorporation Incorporating herbicide was simulated by adding a tillage operation after the application. Three tillage implements were considered: a no-till incorporation, a field cultivation, and a deeper disk cultivation. The following table shows the annual unit area loss for the watershed from the 18- year, 1993 to 2010 period. Supplemental Table S5. Effect of incorporation after application on simulated annual atrazine export from GCEW. Annual Atrazine Loss, g/ha Year Measured Simulated No Conservation Field Disk incorporation tillage implement Cultivation 1993 17.2 14.6 14.2 10.9 6.3 1994 11.2 10.8 10.7 9.6 8.4 1995 18.7 15.8 15.7 14.8 13.5 1996 10.8 11.7 11.3 8.5 4.6 1997 15.2 17.4 17.2 14.6 10.9 1998 11.5 5.0 4.9 4.1 3.0 1999 21.4 17.0 17.0 15.8 14.1 2000 1.5 2.0 1.9 1.4 0.8 2001 16.0 14.7 14.3 11.4 7.7 2002 22.3 19.6 19.6 18.6 18.3 2003 11.6 5.4 5.3 4.2 2.6 2004 4.3 7.5 7.3 5.5 3.0 2005 3.2 2.0 2.0 1.7 1.4 2006 10.7 10.9 10.6 8.2 5.0 2007 8.0 1.8 1.8 1.5 1.2 2008 25.0 26.4 25.9 21.7 15.7 2009 22.1 20.2 20.0 16.9 13.6 2010 11.9 8.9 8.8 7.5 5.7 Average 13.5 11.7 11.6 9.8 7.5 Reduction 2% 17% 36%
S6. Simulated effectiveness of reducing atrazine application rate The following table shows the simulated annual unit area loss for the watershed during the 18- year, 1993 to 2010 period. Supplemental Table S6. Effect of atrazine application rates on simulated atrazine export from GCEW. Annual Atrazine Loss, g/ha Simulated Year Measured Simulated percent reduction in 2.25 kg/ha 1.46 kg/ha atrazine loss 1993 17.2 14.6 9.4 36% 1994 11.2 10.8 6.5 40% 1995 18.7 15.8 9.9 37% 1996 10.8 11.7 7.5 36% 1997 15.2 17.4 10.8 38% 1998 11.5 5.0 3.1 38% 1999 21.4 17.0 10.7 37% 2000 1.5 2.0 1.3 35% 2001 16.0 14.7 9.4 36% 2002 22.3 19.6 12.4 37% 2003 11.6 5.4 3.4 37% 2004 4.3 7.5 4.8 36% 2005 3.2 2.0 1.2 40% 2006 10.7 10.9 7.0 36% 2007 8.0 1.8 1.1 39% 2008 25.0 26.4 17 36% 2009 22.1 20.2 12.6 38% 2010 11.9 8.9 5.5 38% Average 13.5 11.7 7.4 37% S7. References Alberts, E. E., R. C. Wendt, and R. E. Burwell. 1985. Corn and soybean cropping effects on soil losses and C factors. Soil Sci. Soc. Am. J. 49:721-728.