1. Perspectives on the Nitrogen Cycle Peter Vitousek Stanford University

2. We are entering the Anthropocene “the geologic epoch in which the human species has emerged as a globally significant force reshaping the face of Earth” P.J. Crutzen 2002

3. Global Terrestrial N Budget (Galloway and others 2007) “Natural” Biological N Fixation 70 - 100 Lightning 5 Total Fixed Naturally 75 – 105 Inorganic N Fertilizer 100 Crop N Fixation 30 Fossil Fuel Fixation 25 Industrial Uses of fixed N 20 Total Fixed by Humanity ~175

4. EPA Nitrogen Report 2011 United States Nitrogen Budget

5. Vitousek 1994

6. IPCC Third Assessment Report, 2001 100012001400160018002000 Year

8. Robertson and Vitousek 2009

9. Anthropogenic reactive N is distributed unevenly across Earth In some areas we use far too little N, in others we release far too much – and both extremes damage the environment and threaten human well- being.

10. Kenya North China Midwest US Maize Yield 2000 N P All in kg ha-1 y-1 Fertilizer 7 8 Removal in harvested 59 7 products Agronomic inputs minus -52 +1 harvest removals Comparison of Nutrient Balances Sanchez and Palm pers. communication.

11. double crop, w wheat Kenya North China Midwest US Maize Yield 2000 8500 N P N P All in kg ha-1 y-1 Fertilizer 7 8 588 92 Removal in harvested products 59 7 361 39 Agronomic inputs minus harvest removals -52 +1 +227 +53 Comparison of Nutrient Balances Ju et al. 2009

12. Maize-Wheat double-cropping, North China Plain Ju et al. 2009

13. Rotation w/soybean Kenya North China Midwest US Maize Yield 2000 8500 8000 N PN P N P All in kg ha-1 y-1 Fertilizer (plus N fixation) 7 8588 92 155 14 Removal in harvested products 59 7 361 39 145 23 Agronomic inputs minus harvest removals -52 +1 +227 +53 +10 -9 Comparison of Nutrient Balances David and Drinkwater pers communication. (Vitousek et al. 2009)

14. EPA Nitrogen Report 2011

15. Prof. Fusuo Zhang, Dean, College of Resources and Environmental Sciences, China Agricultural University

16. Maize-Wheat double-cropping, North China Plain Ju et al. 2009

17. Yield and Fertilizer Use ISSM versus Farmer Practice Farmer Practice ISSM Maize Yield (t/ha) 6.8 (1.6) 13.0 (1.6) N input (kg/ha) 257 (121) 237 (70) Yield per unit N added (g/g) 26 (20) 57 (13) N inputs minus harvest removals (kg/ha) +127 (42) -12 (56) Chen et al. 2011

18. From P. Johnes (personal communication)

19. We are entering the Anthropocene “the geologic epoch in which the human species has emerged as a globally significant force reshaping the face of Earth” P.J. Crutzen 2002