Reducing Nutrients from Non-Point Sources

1. Reducing Nutrients from Non-Point Sources Matthew Helmers Dean’s Professor, College of Ag. & Life Sciences Professor, Dept. of Ag. and Biosystems Eng. Iowa State University

2. Situation • Increasing concern for local and regional waters • Substantial demand for agricultural products • Hypoxia Action Plan in 2008 called for development and implementation of comprehensive N and P reduction strategies for states in the Mississippi/Atchafalaya River Basin

3. Gulf of Mexico Hypoxia Goals Hypoxia Action Plan Goal: Reduce the size of the zone to 5,000 km2 by 2015 EPA-SAB Recommendations: Reduce Total Riverine Nitrogen and Phosphorus Loads by 45%

4. Can we achieve the nutrient reduction goals for Gulf of Mexico Hypoxia? • Not simple • Not as simple as just fine-tuning nutrient management • Not impossible

5. Approach • Establish baseline – existing conditions • Conduct an extensive literature review to assess potential performance of practices • Outside peer review of science team documents (practice performance and baseline conditions) • Estimate potential load reductions of implementing nutrient reduction practices (scenarios) • “Full implementation” and “Combined” scenarios • Estimate cost of implementation and cost per pound of nitrogen and phosphorus reduction

6. Nitrate-N Reduction Practices *Load reduction not concentration reduction **Concentration reduction of that water interacts with active zone below the buffer

7. Phosphorus Reduction Practices Assessment did not include stream bed and bank contributions although recognized as significant

8. Nutrient Load Reduction Scenarios From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus

9. Nutrient Load Reduction Scenarios From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus

10. Nutrient Load Reduction Scenarios Iowa Conservation Reserve Enhancement Program (CREP) Targeted Wetland Restoration 1 km Source: W. Crumpton From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus

11. Nutrient Load Reduction Scenarios From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction in Nitrogen and 29% reduction in Phosphorus

12. Nutrient Load Reduction Scenarios 100% Crop 10% Prairie - 90% Crop 100% Prairie From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction on Nitrogen and 29% reduction on Phosphorus

13. Overall Comparison of Nitrate-N Practices

14. Overall Comparison of Phosphorus Practices

15. Example:Combination Scenarios that Achieve N and P Goal From Non-Point Sources From Iowa Nutrient Reduction Strategy: Goals for Nonpoint Sources is 41% reduction on Nitrogen and 29% reduction on Phosphorus

16. One Farm What Can We Do?

17. One Location – Many Possibilities

18. Existing Conditions • All row crop land – 1160 acres • Average slope 2.5% • MLRA average N application rate is estimated to be 184 lb-N/acre to corn following beans • Primarily conventional till

19. What Should We Do?

20. Nitrate-N Reduction – What Should We Do? • Nitrogen Management (N rate) • Cover crops • Bioreactors • Wetlands

21. Nitrogen Rate – MLRA 107a

22. What Should We Do? Potential Bioreactor Locations

23. What Should We Do? Potential Wetland Location

24. Nitrate-N Conditions

25. Nitrate-N Combined Scenarios

26. Phosphorus – What Should We Do? • Reduced tillage • Cover Crops • Buffers

27. Estimated Sediment and Phosphorus Loss

28. Potential Prairie Strips Location

29. Example of Prairie Strips Design

30. Education of All Stakeholders will be Key

31. Summary • To achieve goals will require a combination of practices – conservation systems approach • N versus P may require different practices • Multiple benefits and costs of practices need to be considered • Targeting of practice placement will be critical (Precision Conservation)