Description
Corn cultivation has negative impacts to the environment, such as nitrate leaching, soil erosion, and nitrous oxide emissions. Perennial crops such as alfalfa (Medicago sativa L.) reduce annual disturbance of soil, which affects many biogeochemical cycles that are key to provide resilience and stability to cropping systems. Four three-year crop sequences were evaluated. 1) Corn-soybean-corn (CSC); 2) alfalfa-alfalfa-alfalfa (AAA); 3) Corn-spring planted alfalfa-alfalfa (CAA); and 4) Corn-intercropped/alfalfa-alfalfa-alfalfa (CAIAA). Modeling of C and N cycles were conducted with the Denitrification-Decomposition (DNDC) model and global warming potential (GWP) was estimated using life cycle assessment (LCA) methodology. The soil organic carbon (SOC) balance in Year 1 was greater for the CAIAA sequence since alfalfa in intercropping is not removed from the field the first year. In Year 2, CAAIC had the lowest SOC balance due to four harvests of alfalfa removed from the field in Year 2. In Year 3, SOC balances were positive for all sequences but greatest for AAA. This is because in the third-year alfalfa’s root mass increases sequestering carbon deep in the soil. The SOC for the sum of the three-years balance was greater for the CAIAC sequence. Nitrous oxide emissions and nitrate leaching for the three-year sequence were the highest for the CSC sequence and significantly lower for the three sequences containing alfalfa. The main driver of emissions was the nitrogen fertilization added to corn. The net GWP was negative for the CAA and CAIAA sequences, indicating these sequences sequestered carbon. The CAIC sequence had the lowest net GWP of -4509 kg of CO2 e./ha while the CSC sequence had 369 kg of CO2 e./ha.
Included in
Agricultural Science Commons, Agronomy and Crop Sciences Commons, Plant Biology Commons, Plant Pathology Commons, Soil Science Commons, Weed Science Commons
Ecosystem Services and Life Cycle Assessment of Perennial and Annual Cropping Systems
Corn cultivation has negative impacts to the environment, such as nitrate leaching, soil erosion, and nitrous oxide emissions. Perennial crops such as alfalfa (Medicago sativa L.) reduce annual disturbance of soil, which affects many biogeochemical cycles that are key to provide resilience and stability to cropping systems. Four three-year crop sequences were evaluated. 1) Corn-soybean-corn (CSC); 2) alfalfa-alfalfa-alfalfa (AAA); 3) Corn-spring planted alfalfa-alfalfa (CAA); and 4) Corn-intercropped/alfalfa-alfalfa-alfalfa (CAIAA). Modeling of C and N cycles were conducted with the Denitrification-Decomposition (DNDC) model and global warming potential (GWP) was estimated using life cycle assessment (LCA) methodology. The soil organic carbon (SOC) balance in Year 1 was greater for the CAIAA sequence since alfalfa in intercropping is not removed from the field the first year. In Year 2, CAAIC had the lowest SOC balance due to four harvests of alfalfa removed from the field in Year 2. In Year 3, SOC balances were positive for all sequences but greatest for AAA. This is because in the third-year alfalfa’s root mass increases sequestering carbon deep in the soil. The SOC for the sum of the three-years balance was greater for the CAIAC sequence. Nitrous oxide emissions and nitrate leaching for the three-year sequence were the highest for the CSC sequence and significantly lower for the three sequences containing alfalfa. The main driver of emissions was the nitrogen fertilization added to corn. The net GWP was negative for the CAA and CAIAA sequences, indicating these sequences sequestered carbon. The CAIC sequence had the lowest net GWP of -4509 kg of CO2 e./ha while the CSC sequence had 369 kg of CO2 e./ha.
