1. Cropping Systems Affecting Over- winter Soil Nitrate Dynamics and Leaching Chengci Chen, Michael Bestwick, and Yesuf Mohammed Central Ag Research Center Montana State University Nitrate in Montana Hydrologic Systems 2014 Conference, April 23-24, Helena, MT

2. Introduction Soil and weather conditions in central Montana

3. Soil profile

4. Precipitation and Crop Growth Curves

5. Objectives The goal of my research is to improve nitrogen use efficiency, crop yield, and reduce N loss.

6. Approach Application timing: Fall vs. Spring Crop rotations: Fallow-winter wheat vs. Annual cropping Application amount and method:

7. Fall application of N and Br

8. Frozen soil in early spring

9. Surface runoff

10. Crop Rotations

11. Soil NO3 under different crop rotations

12. Yield of Winter Wheat Following Different Crop Rotations

13. Winter wheat response to different rotations

14. Spring wheat yield response to N input in 2013

15. Conclusions Fall-applied N is prone to leaching in central Montana with shallow soil profiles. Fall-applied N may have subjected to surface runoff during snow thawing in the early spring. Crop rotations affected water and N uptake by crops and N mineralization in soils, thereby affecting mineral N contents in the soil profiles. Managing N from leaching to groundwater or runoff to surface water should not sacrifice crop yield and farm profits.

16. Thank You !