1. Residue and nitrogen dynamics in reduced thermal and non- thermal Kentucky bluegrass seed production systems Karl Umiker and Jodi Johnson-Maynard University of Idaho

2. General research objectives: 1. Determine impacts of residue management strategies on nitrogen cycling. 2. Encourage timely residue decomposition.

3. What controls decomposition? 1. Organisms macro to microfauna, microflora 2.Climate 3.Residue status - C:N Approach: To understand the natural reactions that control residue decomposition. Residue decomposition:

4. Residue Carbon Decomposition Amount of carbon Size of residue Type of carbon –% Lignin Availability of nitrogen –how fast and how much

5. C:N Ratio of Materials

6. Site Descriptions Kootenai Co. Site Thermal vs. Non- thermal Annual Harvest Variety: ‘Alene’ Treatments: -Full Load Burn -Bale and Burn -Bale, Mow, and Harrow

7. Kootenai Co. Site – C:N Ratio rake/bale burn mow/harrow

8. Kootenai Co. Site - %N burn rake/balemow/harrow

9. Kootenai Co Site – ‘Alene’ Fall 2002 System Bale/mow/ harrow Bale/burnBurn

10. Kootenai Co. Site – ‘Alene’ Residue Winter mow/harrow bale/ burn

11. Summary: Residue C:N C:N values range from 60 – 13 Values coalesce during the spring Separate fertilizer recommendations may be needed for non-thermal systems –aid in decomposition –nitrate depression Total residue vs. standing and non- standing

12. Summary: Residue Amount Non-thermal treatment at the Kootenai Co. site had ~1 ton/acre more residue than in the thermal treatments Baling may not be necessary in all systems Variety and/or site-specific climate conditions may influence the success of non-thermal residue management practices