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Environmental benefits of kura clover living mulch in annual cropping systems. Tyson Ochsner USDA-ARS Soil and Water Management Research Unit St. Paul, MN. Exp. #1: R 3. Goal:
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Environmental benefits of kura clover living mulch in annual cropping systems Tyson Ochsner USDA-ARS Soil and Water Management Research Unit St. Paul, MN
Exp. #1: R3 • Goal: • Integrated assessment of yield, GHG emissions, nutrient leaching, and long-term changes in soil properties for various cropping practices • Setting: • Rosemount, MN (4445’ N, 9304’ W) • Waukegan silt loam (0.66 – 1.16 m deep) • 879 mm avg. annual precip; 6.4C annual mean temperature • Collaborators: • Rod Venterea (GHG emissions, N transformations, soil properties) • Pam Rice (pesticide fate and transport)
Exp. #1: R3 (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
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 (4445’ N, 9304’ W) • Waukegan silt loam (0.66 – 1.16 m deep) • 879 mm avg. annual precip; 6.4C annual mean temperature • Collaborators: • John Baker (CO2 fluxes, water use, surface energy balance) • Tim Griffis, U of M (gas fluxes, partitioning CO2 exchange)
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
Exp. #3: Arlington • Goal: • Initial assessment of nitrate leaching for corn produced in kura clover living mulch • Setting: • Arlington, WI (4445’ N, 9304’ W) • Plano silt loam • Collaborators: • Ken Albrecht • Bob Berkevich
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
Arlington results: nitrate concentrations • NO3- concentrations • 5X lower in living mulch with no N • 2.5X lower in living mulch +N • Compared to corn in killed kura +N
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