Reducing Nitrous Oxide Emissions Form Soybean Through Early Planting And Cover Crops

Grants and Contracts Details

Description

According to the GREET Life Cycle Analysis model, nitrous oxide (N2O) accounts for 2/3 of greenhouse gas emissions from soybean production. Across the soybean-corn crop system, 1/3 of emissions are attributable to soybean and 2/3 corn. At present, strategies to reduce N2O emissions focus on “4R” (right rate, source, timing, placement) fertilizer management in corn. There are no proven strategies to reduce N2O emissions from soybeans. In 2023, USB funded a modeling project at Iowa State University to test strategies in silico for N2O emissions reduction from soybean (“Opportunities to reduce nitrous oxide emissions from US soybean cropping systems”, $51,300). This work identified two strategies: earlier planting of a longer maturity group soybean, and planting of cover crops prior to soybean. Together, these practices increased soybean yield by 16% and decreased N2O emissions by 28%. On a per bushel basis, N2O emissions estimates in the GREET model were reduced by 33%. Earlier planting of soybeans and cover crops led to better soil nitrogen utilization, holding more nitrogen in crop and allowing less to be lost to the environment. We propose to field-validate these results in four states: Illinois, Iowa, Kentucky, and Minnesota. Each state will plant two soybean varieties on two dates with and without cover crops (MN will use tillage as an alternative to cover crops given the northern location). N2O emissions will be measured weekly. As soybean planting dates are already moving earlier, it is critical to demonstrate (field-validate) how natural progress in soybean management is benefiting the environment.
StatusFinished
Effective start/end date2/1/2412/31/24

Funding

  • Iowa State University: $120,000.00

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