1. Environmental benefits of kura clover living mulch in annual cropping systems Tyson Ochsner USDA-ARS Soil and Water Management Research Unit St. Paul, MN

2. Exp. #1: R 3 Goal: –Integrated assessment of yield, GHG emissions, nutrient leaching, and long-term changes in soil properties for various cropping practices Setting: –Rosemount, MN (44  45’ N, 93  04’ W) –Waukegan silt loam (0.66 – 1.16 m deep) –879 mm avg. annual precip; 6.4  C annual mean temperature Collaborators: –Rod Venterea (GHG emissions, N transformations, soil properties) –Pam Rice (pesticide fate and transport)

4. Exp. #1: R 3 (continued) Design: –Total of 39 large plots (76 m x 27 m) –4 tillage practices, 3 crop rotations, 2 N sources, 3 replicates History: –Main treatments (4 tillage types, C/C, C/S) established 2000 –Kura clover added 2006 Instrumentation: –Static and automated chambers for GHG emissions –Automated equilibrium tension lysimeters for drainage and leaching –Soil water content sensors –Soil temperature sensors –Recording rain gauges –3 comprehensive weather stations within 2 km

6. Exp. #2: GRACENet Goal: –Field scale assessment of yield, carbon sequestration, water use, and long-term changes in soil properties for various cropping sytems Setting: –Rosemount, MN (44  45’ N, 93  04’ W) –Waukegan silt loam (0.66 – 1.16 m deep) –879 mm avg. annual precip; 6.4  C annual mean temperature Collaborators: –John Baker (CO 2 fluxes, water use, surface energy balance) –Tim Griffis, U of M (gas fluxes, partitioning CO 2 exchange)

7. Exp. #2: GRACENet (continued) Design: –Three adjacent large fields (>40 acres each) –Three distinct cropping systems Conventional C/S C/S with reduced tillage and rye cover crop after corn Kura clover living mulch History: –Rye cover crop initiated fall 2003 –Kura clover planted spring 2006 Instrumentation: –Eddy covariance systems and tunable diode laser for water use and GHG exchange –Comprehensive suite of meteorological sensors –Automated equilibrium tension lysimeters for drainage and leaching –Soil water content and temperature sensors

9. Exp. #3: Arlington Goal: –Initial assessment of nitrate leaching for corn produced in kura clover living mulch Setting: –Arlington, WI (44  45’ N, 93  04’ W) –Plano silt loam Collaborators: –Ken Albrecht –Bob Berkevich

10. Exp. #3: Arlington (continued) Design: –Randomize complete block, 4 reps –Corn in living mulch with 0, 20, 40, 60, and 80 lbs/acre N –Corn without living mulch History: –Experiment initiated spring 2006 in mature kura clover stand –Second year corn in 2007 Instrumentation: –Suction cup samplers for nitrate concentration –Tensiometers –Soil water content sensors –Nearby weather station

15. Arlington results: nitrate concentrations NO 3 - concentrations –5X lower in living mulch with no N –2.5X lower in living mulch +N –Compared to corn in killed kura +N

16. Research needs Establishment methods and economics Crop rotation and management N rate, fixation, transfer, and losses Water use and competition Light use and competition GHG emissions, carbon sequestration N and P leaching Pesticide transport Erosion reduction Ecological benefits Net energy production