COVER CROPPING FOR SUSTAINABLE CO-PRODUCTION OF BIOENERGY, FOOD, FEED (BFF) AND ENHANCEMENT OF ECOSYSTEM SERVICES (ES)
thesisposted on 18.12.2020, 16:17 by Brodrick L DenoBrodrick L Deno
Increasing food, feed, fiber, biofuel production on decreasing amounts of arable land while simultaneously enhancing ecosystem services is challenging. Strategic inclusion of winter rye (Secale cereale) for biomass, silage, grain and Kura clover (Trifolium ambiguum) living mulch into existing Midwestern cropping systems may offer alternative economic income for farmers without displacing or reducing yields of primary crops. Research was conducted at the Purdue Water Quality Field Station (WQFS) where net balances of water, carbon, nitrogen, and radiation can be measured, and greenhouse gas (GHG) emissions are monitored. The agronomic performance of a corn-soybean rotation and continuous corn (controls) were compared to novel systems that included the use of rye cover cropping and Kura clover co-cropping. Rye was harvested for biomass/silage at heading immediately followed by corn or soybean planting. Continuous corn receiving 69 kg N ha-1 was planted into an establishment of Kura clover sod. Controls included these same systems without the rye or clover. GHG samples were taken via the static chamber method and tile-drained water sub-samples were collected, analyzed for nitrate, and load losses calculated. Biomass composition was determined and used to calculate herbage theoretical ethanol (EtOH) yields. Cereal rye did not significantly decrease corn or soybean grain yield. Averaged across years, Kura clover significantly depressed corn grain yields by nearly 70%. Kura clover significantly reduced flow-weighted tile drainage nitrate (NO3-) concentrations, however cereal rye did not. Reductions in flow-weighted tile drainage nitrate (NO3-) concentrations were found to largely occur during Quarter two (April, May, June). Cover crops did not significantly reduce annual tile drained NO3- load losses in most cases, however, they did significantly reduce annual N2O emissions. Cumulative annual CH4 emissions were not significantly altered. Annual CO2emissions were higher after the introduction of Kura clover and not significantly altered following the introduction of cereal rye. Averaged across years, theoretical ethanol yields in the Kura clover system produced 2,752 L EtOH ha-1, whereas EtOH production in cereal rye systems ranged from 3,245 to 4,210 L EtOH ha-1. Theoretical ethanol yields of continuous corn and rotational controls ranged from 2,982 to 3505 L EtOH ha-1 for these same systems without the cereal rye of Kura clover. These data suggest that a multipurpose approach to cover crop inclusion can provide both environmental and economic advantages worthy of consideration.
Cover Cropping For Sustainable Co-Production of Bioenergy, Food, Feed (BFF) and Ecosystem Services (ES)
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