Supporting Information Changes in environmental impacts of major crops in the U.S.

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1 Supporting Information Changes in environmental impacts of major crops in the U.S. Yi Yang and Sangwon Suh* Bren School of Environmental Science and Management, University of California, Santa Barbara, CA * The author to whom correspondence should be made suh@bren.ucsb.edu Office Phone: (805) Fax: (805) Table 21 Pape 21 1

2 1. Impact categories selected from TRACI 2.0 for analysis Table S1. Detailed information on impact categories selected from TRACI 2.0 Impact category Media Unit Explanation Acidification air moles of Increases in hydrogen ion (H+) within a H+ eq local environment Eutrophication water kg N eq Nutrient buildup in aquatic ecosystems that stimulates excessive biological productivity such as algal growth Smog formation air kg O 3 eq Photochemical reactions between nitrogen oxides (NO x) and volatile organic compounds (VOCs), resulting in a range of respiratory issues Freshwater ecotoxicity Human health respiratory Human health cancer Human health noncancer multimedia CTUe air kg PM 10 eq multimedia CTUh multimedia CTUh Estimates of the potentially affected fraction of species (PAF), expressed in comparative toxic units (CTUe) Criteria pollutants such as particulate matter that cause respiratory illness and death. Increases in morbidity in the total human population, expressed in comparative toxic units (CTUe) Increases in morbidity (e.g., reproductive, developmental, and neurotoxic effects) in the total human population, expressed in comparative toxic units (CTUe) 2

3 2. Numerical information on inputs applied to major crops in the U.S. Tables S2-S5 present inputs data that were used for LCA calculation in this study. It is worth noting that a large number of pesticides were applied to the four crops in the years investigated: 84 for corn, 113 for cotton, 81 for soybean, and 65 for wheat. But these are not the complete list of pesticides applied because USDA, the department that collects such data, often withholds information on certain pesticides to avoid disclosing data from individual farms. The pesticides unpublished are usually applied in a small number of states and in small amounts, which get lumped in the total amount of herbicides, insecticides, fungicides, or other chemicals disclosed for all the states surveyed. The amount of pesticides published and specified in general accounts for 95% of the total applied. There are a few pesticides not consistently published for the years investigated; they are denoted NA in Tables S2-S5. The inconsistency reflects, in most cases, changes in the number of states applying the pesticides and, as a result, changes in the amount applied. For example, bromoxynil was published for corn production in years 2001 and 2005 but not for that in A closer examination of the state-level pesticide data shows that the pesticide was applied in 12 states in 2001 and 9 states in 2005 but only in 1 state in It was hypothesized that given their small amounts, the unpublished pesticides (i.e., NAs) would have little effect on the overall freshwater ecotoxicity impact. To rigorously test this hypothesis, we run the following analysis. First, we replaced all the NAs for given years with maximal rates (kg ha -1 ) identified from other years. In the case of bromoxynil applied to corn, for example, we replaced the NA for 2010 with from This would be considered a worst-case, unlikely scenario given the number of states dropped significantly that applied this pesticide. Next, we recalculated the freshwater ecotoxicity impact and compared how much it had changed for each crop. The results generally confirmed our hypothesis. The new ecotoxicity impact per ha corn produced would increase by <2% for all years; the same goes for soybean. The new impact per ha wheat produced would increase by <6% for all years. And the new impact per ha cotton produced would increase by <2% for 2000 and 2003 but by around 13% for This is because the unpublished pesticides are generally in small amounts relative to other pesticides and their freshwater ecotoxicity potentials as assigned by TRACI 2.0 are also relatively small. The results also identified several pesticides worth of further analysis. For 2007 cotton, we identified cyanazine, fenpropathrin, and profenofos as the major contributor to the large difference (i.e., 13% increase) if their NAs (kg ha -1 ) were replaced with maximal rates. We took a further look into the state-level data and estimated their 2007 application rates (kg ha -1 ) based on the number of states that applied these pesticides in that year relative to the number of state that applied the pesticides in 2003 given no further information available. All other pesticides with NAs were treated as 0s in our LCA analysis considering their insignificant contributions as demonstrated above. 3

4 Table S2. Inputs use in U.S. corn production (ha -1 ) Energy diesel kg gasoline kg lpg kg electricity kwh natural gas mj Nutrient nitrogen kg phosphate kg potash kg sulfur kg Pesticide 2,4-d kg NA NA 2,4-d, 2-ehe kg ,4-d, bee kg ,4-d, dieth. salt kg ,4-d, dimeth. salt kg NA ,4-d, isoprop. salt kg acetochlor kg acifluorfen, sodium kg alachlor kg ametryn kg atrazine kg azoxystrobin kg 0 NA bentazon kg NA 0 bifenthrin kg bromoxynil kg NA bromoxynil heptan. kg NA bromoxynil octanoate kg NA NA carbofuran kg NA carfentrazone-ethyl kg E E-05 chlorpyrifos kg clopyralid kg cyanazine kg cyfluthrin kg dicamba kg dicamba, digly salt kg dicamba, dimet. salt kg dicamba, pot. salt kg dicamba, sodium salt kg diflufenzopyr-sodium kg dimethenamid kg dimethenamid-p kg NA dimethoate kg eptc kg NA NA esfenvalerate kg 1.72E NA fipronil kg NA flufenacet kg

5 flumetsulam kg foramsulfuron kg glufosinate-ammonium kg glyphosate kg glyphosate amm. salt kg E glyphosate iso. salt kg glyphosate pot. salt kg halosulfuron kg E-05 imazapyr kg 6.87E NA imazethapyr kg NA isoxaflutole kg lambda-cyhalothrin kg linuron kg NA mcpa kg mcpa, sodium salt kg mesotrione kg methyl parathion kg metolachlor kg metribuzin kg NA nicosulfuron kg paraquat kg pendimethalin kg permethrin kg petroleum distillate kg NA 0 phorate kg NA 0 primisulfuron kg E-05 propargite kg propiconazole kg NA NA prosulfuron kg E-05 pyraclostrobin kg pyridate kg NA 0 rimsulfuron kg saflufenacil kg simazine kg s-metolachlor kg spiromesifen kg sulfosate kg tebupirimphos kg tefluthrin kg tembotrione kg terbufos kg thiencarbazone-methy kg thifensulfuron kg 3.44E topramezone kg trifloxystrobin kg trifluralin kg NA vernolate kg zeta-cypermethrin kg E-05 unspecified kg

6 Table S3. Inputs use in U.S. cotton production (ha -1 ) Energy diesel kg gasoline kg lpg kg electricity kwh natural gas mj Nutrient nitrogen kg phosphate kg photash kg sulfur kg Pesticide 2,4-d kg NA 2,4-d, 2-ehe kg ,4-d, dimeth. salt kg 0 NA abamectin kg acephate kg acetamiprid kg aldicarb kg amitraz kg arsenic acid kg azinphos-methyl kg NA 0 azoxystrobin kg barban kg bifenthrin kg bromoxynil kg buprofezin kg NA cacodylic acid kg NA carbofuran kg NA carboxin kg E-05 NA carfentrazone-ethyl kg chlorpyrifos kg clethodim kg clomazone kg cyanazine kg cyclanilide kg cyfluthrin kg cypermethrin kg deltamethrin kg NA dicamba kg NA dicamba, digly. salt kg

7 dicamba, dimet. salt kg dicamba, sodium salt kg dichloropropene kg NA NA dicofol kg dicrotophos kg diflubenzuron kg NA NA dimethipin kg NA dimethoate kg disulfoton kg diuron kg dsma kg emamectin benzoate kg NA NA endosulfan kg NA endothall kg esfenvalerate kg ethephon kg etoxazole kg etridiazole kg fenoxaprop kg fenpropathrin kg flonicamid kg fluazifop-p-butyl kg NA NA flumiclorac-pentyl kg 0 NA flumioxazin kg 0 NA fluometuron kg fomesafen kg NA glufosinate-ammonium kg glyphosate kg glyphosate amm. salt kg glyphosate dia. salt kg glyphosate iso. salt kg imidacloprid kg indoxacarb kg iprodione kg NA lactofen kg NA lambda-cyhalothrin kg linuron kg malathion kg mefenoxam kg mepiquat chloride kg mepiquat pentaborate kg metalaxyl kg NA methamidophos kg

8 methomyl kg NA methoxyfenozide kg methyl parathion kg metolachlor kg monocarbamide dihyd. kg msma kg naled kg NA norflurazon kg novaluron kg oxamyl kg oxyfluorfen kg paraquat kg pcnb kg pendimethalin kg permethrin kg 9.24E petroleum distillate kg NA phorate kg profenofos kg prometryn kg propargite kg NA pyraflufen-ethyl kg pyridate kg NA 0 pyriproxyfen kg pyrithiobac-sodium kg quizalofop-ethyl kg 9.24E sethoxydim kg NA s-metolachlor kg sodium chlorate kg spinosad kg spiromesifen kg sulfosate kg NA tebufenozide kg thiamethoxam kg thidiazuron kg thifensulfuron kg NA thiodicarb kg NA 0 tralomethrin kg tribufos kg trifloxysulfuron-sod kg trifluralin kg zeta-cypermethrin kg unspecified kg

9 Table S4. Inputs use in U.S. soybean production (ha -1 ) Energy diesel kg gasoline kg lp gas kg electricity kwh natural gas mj Nutrient nitrogen kg phosphate kg potash kg sulfur kg biofixed N Pesticide 2,4-d kg NA ,4-d, 2-ehe kg ,4-d, bee kg ,4-d, dimeth. salt kg ,4-db, dimeth. salt kg 4.77E-05 NA NA acephate kg NA acetochlor kg 0 NA acifluorfen, sodium kg alachlor kg NA azoxystrobin kg bentazon kg NA beta-cyfluthrin kg E-05 bifenthrin kg carbaryl kg NA carfentrazone-ethyl kg 1.59E E-05 chlorimuron-ethyl kg chlorpyrifos kg clethodim kg clomazone kg NA cloransulam-methyl kg cyfluthrin kg cypermethrin kg NA NA dicamba, digly. salt kg dicamba, dimet. salt kg 0 NA diflubenzuron kg 7.95E E-05 dimethenamid-p kg 0 NA dimethoate kg esfenvalerate kg

10 ethalfluralin kg NA 0 fenoxaprop kg fenoxaprop-p-ethyl kg fluazifop-p-butyl kg flubendiamide kg flufenacet kg NA flumetsulam kg flumiclorac-pentyl kg flumioxazin kg fluthiacet-methyl kg fomesafen kg gamma-cyhalothrin kg E E-05 glufosinate-ammonium kg 0 NA glyphosate kg glyphosate amm. salt kg NA glyphosate dia. salt kg glyphosate dim. salt kg glyphosate iso. salt kg glyphosate pot. salt kg imazamox kg E-05 imazaquin kg imazaquin, mon. salt kg imazaquin, sod. salt kg 3.18E imazethapyr kg imazethapyr, ammon. kg E imidacloprid kg lactofen kg lambda-cyhalothrin kg methoxyfenozide kg methyl parathion kg NA metolachlor kg metribuzin kg paraquat kg pendimethalin kg permethrin kg NA propiconazole kg pyraclostrobin kg quizalofop-p-ethyl kg rimsulfuron kg 0 NA 6.12E-05 saflufenacil kg sethoxydim kg s-metolachlor kg sulfentrazone kg

11 sulfosate kg tebuconazole kg NA tetraconazole kg 0 NA thiamethoxam kg thifensulfuron kg 6.36E E thiodicarb kg NA tribenuron-methyl kg 3.18E E trifloxystrobin kg trifluralin kg zeta-cypermethrin kg E-05 unspecified kg Table S5. Inputs use in U.S. wheat production (ha -1 ) Energy diesel gasoline lp gas electricity natural gas Nutrient nitrogen phosphate potash sulfur Pesticide 2,4-d NA 2,4-d, 2-ehe ,4-d, bee NA 2,4-d, dieth. salt ,4-d, dimeth. salt NA ,4-d, isoprop. salt ,4-dp, dimeth. salt NA atrazine NA NA azoxystrobin beta-cyfluthrin E-05 bromoxynil bromoxynil heptan bromoxynil octanoate carfentrazone-ethyl 0 2.5E E-05 chlorpyrifos chlorsulfuron

12 clodinafop-propargil NA clopyralid cyfluthrin E-05 dicamba dicamba, dimet. salt NA NA dicamba, sodium salt diclofop-methyl NA dimethoate diuron ethyl parathion fenoxaprop fenoxaprop-p-ethyl flucarbazone-sodium flufenacet NA fluroxypyr fluroxypyr 1-mhe glyphosate glyphosate iso. salt glyphosate pot. salt imazamethabenz NA imazamox lambda-cyhalothrin 4.85E mcpa mcpa, 2-ethylhexyl mcpa, dimethyl. salt mcpa, isooctyl ester mesosulfuron-methyl 2.43E E methyl parathion NA NA methanone metribuzin metsulfuron-methyl picloram, k salt E-05 NA pinoxaden propiconazole propoxycarbazone-sod prosulfuron 7.28E E prothioconazole pyraclostrobin pyroxsulam sulfosulfuron tebuconazole thifensulfuron tralkoxydim NA 12

13 triallate NA triasulfuron tribenuron-methyl trifloxystrobin trifluralin zeta-cypermethrin NA unspecified Table S6. Average irrigation water use per ha crop produced in the U.S. Corn Cotton Soybean Wheat Noted: Results are calculated based on (irrigation intensity for irrigated area area irrigated) / total area harvested. 13

14 3. Data on emission factors Table S7. Nitrogen (N) and Phosphorus (P) runoff and leaching rates (% of the amount applied) Corn Soybean Wheat N P N P N P CO 13 9 AR CO 5 6 GA IL 9 43 ID IL IN 9 43 IL 14 8 IN IA 9 43 KS IA KS MN 14 8 KS KY MO KY LA MT 5 6 MI MI 9 43 NE 5 6 MN MN 9 43 ND 5 6 MO MS OH NE 13 9 MO OK NY NE 8 29 OR NC NC 30 8 SD 5 6 ND 13 9 ND 8 29 TX OH OH WA PA SD 8 29 SD 13 9 TN TX VA 30 8 WI WI 9 43 Note: Nutrient loss rates for each state are derived from regional (multistate) nutrient loss rates according to the location of the state relative to that of the region, mostly multi-states, modeled in the reference. If a state occupies parts of several regions, the average of the regional rates is used. 14

15 Table S8. Speciated VOC emissions from natural gas- and diesel-engine farm machinery Natural Gas (kg/mj) Diesel Substances 2-stroke 4-stroke 4-stroke lean-burn lean-burn rich-burn kg/kg 1,1,2,2-Tetrachloroethane 2.9E E E E+00 1,1,2-Trichloroethane 2.3E E E E+00 1,1-Dichloroethane 1.7E E E E+00 1,2,3-Trimethylbenzene 1.5E E E E+00 1,2,4-Trimethylbenzene 4.8E E E E+00 1,2-Dichloroethane 1.8E E E E+00 1,2-Dichloropropane 1.9E E E E+00 1,3,5-Trimethylbenzene 7.7E E E E+00 1,3-Butadiene 3.5E E E E-07 1,3-Dichloropropene 1.9E E E E+00 2,2,4-Trimethylpentane 3.6E E E E+00 2-Methylnaphthalene 9.2E E E E+00 Acenaphthene 5.7E E E E-08 Acenaphthylene 1.4E E E E-08 Acetaldehyde 3.3E E E E-05 Acrolein 3.3E E E E-06 Anthracene 3.1E E E E-08 Benz(a)anthracene 1.4E E E E-08 Benzene 8.3E E E E-05 Benzo(a)pyrene 2.4E E E E+00 Benzo(b)fluoranthene 3.7E E E E-09 Benzo(e)pyrene 1.0E E E E-09 Benzo(g,h,i)perylene 1.1E E E E-09 Benzo(k)fluoranthene 1.8E E E E-09 Biphenyl 1.7E E E E+00 Butane 2.0E E E E+00 Butyr/Isobutyraldehyde 1.9E E E E+00 Carbon Tetrachloride 2.6E E E E+00 Chlorobenzene 1.9E E E E+00 Chloroethane 0.0E E E E+00 Chloroform 2.0E E E E+00 Chrysene 2.9E E E E-09 Cyclohexane 1.3E E E E+00 Cyclopentane 4.1E E E E+00 Dibenz(a,h)anthracene 0.0E E E E-08 Ethane 3.1E E E E+00 Ethylbenzene 4.6E E E E+00 Ethylene Dibromide 3.2E E E E+00 15

16 Fluoranthene 1.6E E E E-07 Fluorene 7.3E E E E-07 Formaldehyde 2.4E E E E-05 Indeno(1,2,3-c,d)pyrene 4.3E E E E-09 Isobutane 1.6E E E E+00 Methanol 1.1E E E E+00 Methylcyclohexane 1.5E E E E+00 Methylene Chloride 6.3E E E E+00 n-hexane 1.9E E E E+00 n-nonane 1.3E E E E+00 n-octane 3.2E E E E+00 n-pentane 6.6E E E E+00 Naphthalene 4.1E E E E-06 Perylene 2.1E E E E+00 Phenanthrene 1.5E E E E-07 Phenol 1.8E E E E+00 Propane 1.2E E E E+00 Propylene 0.0E E E E-05 Pyrene 2.5E E E E-08 Styrene 2.4E E E E+00 Tetrachloroethanek 0.0E E E E+00 Toluene 4.1E E E E-06 Vinyl Chloride 1.1E E E E+00 Xylene 1.2E E E E-06 Note: For natural gas, average emission factors for different modes are used for analysis in this study. Table S9. Emission factors for fuel combustion (mg MJ -1 ) Diesel Gasoline LPG NG Farming Tractor Farming Tractor Commercial Boiler Stationary Reciprocating Engine CO NOx PM PM SOx

17 Table S10. Estimation of pesticide releases into different compartments Compartment Fraction Note 95% p(vapor pressure) >10 (mpa) 50% 1<p<10 Air 15% 0.1<p<1 5% 0.01<p<0.1 1% p<0.01 Water 0.5% Generic runoff and leaching rate Soil 1-air-water Capped at 85% Table S11. Average heavy metal concentrations in U.S. phosphate rock and fertilizer Heavy metal concentration, mg/kg As Cd Cr b Pb Hg Ni V Phosphate rock P2O5 fertilizers Note: Cr is assumed to exist in the form of Cr (III) in agricultural soil, because Cr (VI), being a strong oxidizing agent, is likely to be reduced to Cr (III) through reaction with soil organic matter or other reducing agents. For 1 kg As emitted, 0.5 kg is assumed to exist in As (III) and the other half in As (V) due to a lack of more precise insights into the issue. Table S12. Emission factors for NH 3 and NO X from nitrogen NH 3 NO X Emission factor 3.5% 2.5% 17

18 4. Estimation of biological nitrogen fixation for soybean Nitrogen input through biological nitrogen fixation (BNF), due to nitrogen-fixing bacteria hosted symbiotically by the legume crops, can also be a source of nitrogen pollution 1. Here, we estimated the total amount of BNF for soybean production in the major states covered, based on a USDA study that quantified nutrient inputs from multiple sources to major U.S. crops in a single year. 1 Their estimates of BNF ranged from 91 to 243 kg ha -1 for 7 geographic regions into which the study classified the continental United States. We first derived state-level estimates from the regional estimates based on the location of the state relative to the regions classified in the USDA study. We assumed that the rates remained unchanged over the period investigated given that there is no strong evidence that the environmental factors 2 affecting BNF changed have significantly in the past decade or. Based on the state rates, we further calculated the average rate for per ha soybean in the U.S., which is about 185 kg ha -1. The total amount of BNF calculated for the 19 to 20 states major soybean-producing states covered in this study is around 5.4 Tg yr -1, which is close to a recent estimate of 5.7 Tg calculated for the entire country Results Table S13. Life-cycle, cradle-to-gate impact per ha crop produced (TRACI 2.0) Corn Cotton ACD moles of H+ eq EUT kg N eq SF kg O3 eq HHR kg PM10 eq FET CTUe HHC CTUh 5.3E E E E E E-05 HHNC CTUh 4.4E E E E E E-04 Soybean Wheat ACD moles of H+ eq EUT kg N eq SF kg O3 eq HHR kg PM10 eq FET CTUe HHC CTUh 6.7E E E E E E-05 HHNC CTUh 1.0E E E E E E-04 18

19 6. Comparison between TRACI 2.0, IMPACT 2002+, and CML 2001 To test the robustness of our result on freshwater ecotoxicity impact, we applied two additional characterization models, IMPACT and CML 2001, to evaluating the inventory data compiled. Because pesticide releases were identified as the major contributor to freshwater ecotoxicity (see figure 3 in the manuscript), the other two models were used to characterize pesticide releases only. The impact categories in IMPACT and CML 2001 that correspond to freshwater ecotoxicity in TRACI 2.0 are aquatic ecotoxicity. Estimation of pesticide releases to different compartments was kept the same for all three methods (see section 2.4. in the manuscript). Results are presented below. Two factors lead to the differences in the magnitude of change calculated by the three characterization models (see also figure 5 in the manuscript). First, different models cover different numbers of pesticides. TRACI 2.0, whose freshwater ecotoxicity impact category is adopted from USEtox, 4 covers the largest number of pesticides, with 63/84 for corn, 89/113 for cotton, 55/81 for soybean, and 48/65 for wheat. Compare this with CML 2001 (19/84 for corn, 23/113 for cotton, 16/81 for soybean, and 13/65 for wheat) and IMPACT (63/84 for corn, 89/113 for cotton, 55/81 for soybean, and 48/65 for wheat). Second, different characterization models give different ecotoxicity potentials to different pesticides. In TRACI 2.0, for example, cyfluthrin shows the largest freshwater ecotoxicity potential, which is 300 times that of atrazine. In IMPACT 2002+, however, lambda-cyhalothrin shows the largest aquatic ecotoxicity potential, and that of cyfluthrin is only 17 times that of atrazine. Tables S14-S17 present impact results based on CML 2001 and contributions of key pesticides identified. Table S14. Aquatic ecotoxicity impact per ha corn produced and contributions of key pesticides (unit: kg 1,4-dichlorobenzene eq.) atrazine 22% 22% 25% chlorpyrifos 14% 9% 3% metolachlor 15% 4% 1% permethrin 7% 4% 3% simazine 4% 6% 7% s-metolachlor 36% 51% 60% other pesticides 2% 4% 1% total Table S15. Aquatic ecotoxicity impact per ha cotton produced and contributions of key pesticides (unit: kg 1,4-dichlorobenzene eq.) aldicarb 66% 78% 83% cypermethrin 6% 9% 10% malathion 23% 7% 3% other pesticides 5% 6% 4% total

20 Table S16. Aquatic ecotoxicity impact per ha cotton produced and contributions of key pesticides (unit: kg 1,4-dichlorobenzene eq.) chlorpyrifos 11% 71% 50% metolachlor 10% 0% 2% permethrin 7% 1% 0% s-metolachlor 23% 10% 38% trifluralin 25% 6% 3% zeta-cypermethrin 16% 10% 2% other pesticides 9% 1% 6% total Table S17. Aquatic ecotoxicity impact per ha cotton produced and contributions of key pesticides (unit: kg 1,4-dichlorobenzene eq.) chlorpyrifos 66% 33% 68% ethyl parathion 0% 18% 0% methanone 0% 0% 8% triallate 22% 1% 1% trifluralin 5% 1% 0% zeta-cypermethrin 0% 42% 23% other pesticides 7% 5% 0% total Tables S18-21 present impact results based on IMPACT and contributions of key pesticides identified. Table S18. Aquatic ecotoxicity impact per ha corn produced and contributions of key pesticides (unit: kg triethylene glycol. eq.) atrazine 98% 98% 99% other pesticides 2% 2% 1% total

21 Table S19. Aquatic ecotoxicity impact per ha cotton produced and contributions of key pesticides (unit: kg triethylene glycol. eq.) aldicarb 18% 21% 21% chlorpyrifos 5% 2% 0% cyanazine 4% 0% 0% cyfluthrin 4% 3% 3% diuron 5% 10% 13% lambda-cyhalothrin 4% 4% 4% malathion 3% 1% 0% methomyl 4% 3% 0% prometryn 17% 21% 19% tribufos 17% 16% 24% trifluralin 4% 5% 5% other pesticides 16% 13% 10% total Table S20. Aquatic ecotoxicity impact per ha soybean produced and contributions of key pesticides (unit: kg triethylene glycol. eq.) chlorpyrifos 5% 42% 30% glyphosate 32% 1% 2% lambda-cyhalothrin 9% 28% 23% metribuzin 13% 13% 11% pendimethalin 7% 2% 1% s-metolachlor 9% 5% 19% trifluralin 13% 4% 2% other pesticides 13% 4% 12% total Table S21. Aquatic ecotoxicity impact per ha wheat produced and contributions of key pesticides (unit: kg triethylene glycol. eq.) atrazine 47% 71% 60% bromoxynil 19% 8% 0% chlorpyrifos 16% 9% 23% triallate 7% 1% 0% other inputs 12% 11% 17% total

22 References 1. USDA. Model Simulation of Soil Loss, Nutrient Loss, and Change in Soil Organic Carbon Associated with Crop Production. Natural Resource Conservation Service, US Department of Agriculture; Zahran HH. Rhizobium-Legume Symbiosis and Nitrogen Fixation under Severe Conditions and in an Arid Climate. Microbiol Mol Biol Rev Dec 1;63(4): Herridge DF, Peoples MB, Boddey RM. Global inputs of biological nitrogen fixation in agricultural systems. Plant Soil. 2008;311(1-2): Rosenbaum RK, Bachmann TM, Gold LS, Huijbregts MAJ, Jolliet O, Juraske R, et al. USEtox the UNEP-SETAC toxicity model: recommended characterisation factors for human toxicity and freshwater ecotoxicity in life cycle impact assessment. Int J Life Cycle Assess Nov 1;13(7):