1. Clain Jones, Andrew John, Adam Sigler, Perry Miller and Stephanie Ewing Department of Land Resources and Environmental Sciences Effect of Agricultural Practices on Nitrate Leaching in the Judith River Watershed

2. Project Sub-Objectives Evaluate the effects of alternative agricultural management practices on: 1.Nitrate Leaching 2.Net Revenue

3. Nitrate leaching in Montana agroecosystems: Concept and timing Highest precipitation period: Late Apr to Mid-June Highest nitrate levels in soil: after fallow and after fertilization (often Apr in Judith Basin) How do those periods compare with crop N uptake? Fallow

4. Top-dress amount and timing based on wheat growth stage to not hurt yield Nutrient Uptake Timing (EB0191) http://landresources.montana.edu/soilfertility/publications.html Saskatchewan Adapted from Malhi et al. 2006 Apr May June JulyAug

5. Deep Soil Water Collected

6. Practices that can decrease nitrate leaching in agro-ecosystems Seed perennial and/or deep rooted annual crops Sprinkle vs flood irrigation Soil sample for nitrate to determine N fertilizer rate Select reasonable yield goal Credit N from manure and legumes Fertilize in spring rather than fall Use a slow release fertilizer Split application Grow legumes (don’t need to fertilize with N) Recrop (crop every year) rather than summer fallow

7. Study Design: Management Practices Grower Standard Practice (GSP) Wheat-barley-fallow rotation Nitrogen fertilizer: surface broadcast, early spring Alternative Management Practices (AMP) vs GSP Pea vs Fallow Split fertilizer application vs single early spring broadcast Controlled release urea (CRU) with seed vs early spring broadcast Alternative management practices were selected by our two research advisory groups based on how adoptable the practices were

8. Study Design: Fields Comparisons of AMP vs GSP treatments were made for two years (2013, 2014) on two fields each. Fields located near Stanford (Field A), Moccasin (Field B), and Moore (Field C) Field A

9. Field B Study Design: Field Layout and Sampling Locations 2014 Winter Wheat GSP AMP

10. 2012 2013 2014 CRUGSPSplit App Fallow CRUGSPSplit App Study Design: Field C (near Moore)

11. Calculating Leaching by Nitrogen Mass Balance Leached Nitrate = Inputs – outputs + initial soil nitrate – final soil nitrate

12. Nitrogen Mass Balance Leached Nitrate = Fertilizer N + N fixed + Net N mineralized – denitrification – crop N uptake – N volatilized + initial soil nitrate – final soil nitrate Fertilizer N: from Judith collaborators N-fixed: natural abundance method Net N mineralized – denitrification: soil nitrate differences when no leaching based on precipitation and soil moisture (e.g. 2012 to mid-May 2013). Modelled during other periods. Crop N uptake  biomass sampling N volatilized  Rick Engel’s results from Fergus County

13. Status of leaching estimate Still developing mineralization model Can calculate available N recovery for 2013 winter wheat. Available N Recovery (%) = ((N in grain and straw)/(soil nitrate in Aug 2012 + fertilizer N))*100 Differences between treatments could suggest differences in leaching

14. Available Nitrogen Recovery in 2013 winter wheat * - Significant difference (P<0.05) Values well below 100% suggest substantial losses Why did pea likely reduce N leaching?

15. Soil nitrate differences following pea vs fallow in top 30 cm, Aug 2012

16. Soil water differences following pea vs fallow top 30 cm, August 2012

17. Take home messages and thoughts Minimizing deep percolation (by eliminating fallow) likely minimizes leaching more than adjusting N fertilizer treatments We will sample soil and biomass for one more season before developing recommendations Decreasing nitrate leaching basin-wide will require a concerted effort among producers, educators, stakeholders, and policy makers, as well as patience

18. For more information on factors affecting nitrate leaching go to: http://landresources.montana.edu/soilfertility MT201103AG (under Extension Publications)

19. Thank You! Questions? Acknowledgments Funded by: USDA (National Integrated Water Quality Program) Co-PI: Douglas Jackson-Smith Collaborators: Jim Kulish Brandon Morris Greg Grove Advisory committee and producer research advisory committee members: Jane Holzer, Mark McLendon, Curtis Hershberger, Terry Metcalfe, Dave Wichman, Ken Ronish, Chrissy Cook, Darren Crawford, Pat Hensleigh, Patty Creamer, Deen Pomeroy, Rick Caquelin, Greg Grove, Bing Von Bergen, Tom Butcher, Jim Kulish, Nita Bronec, Brandon Morris, Dave Linker; facilitator: Dave Phillips Others: Anton Beckerman, Terry Rick, Rosie Wallander, Jeff Holmes, Sebastian Schnobrich, Katelyn John, Chris Kubicki, Stephen Johnson, Christine Miller, Anthony Stewart, Britton Tew, Jay Rosencrantz