Greenhouse gas emissions from tillage practices and crop phases in a sugarbeet-based crop rotation

Information is needed on greenhouse gas (GHG) emissions due to tillage and crop type on sugarbeet (Beta vulgaris L.)-based crop rotations. We measured CO2, N2O, and CH4 emissions as affected by tillage (conventional till [CT], no-till [NT], and strip till [ST]) under sugarbeet and spring wheat (Triticum aestivum L.) phases of an irrigated sugarbeet-pea (Pisum sativum L.)-spring wheat rotation from 2018 to 2021 in the US northern Great Plains. Greenhouse gases were measured using a static chamber at 3- to 28-day intervals, depending on plant growth and environmental conditions, throughout the year. The CO2 and N2O fluxes peaked for 2-8 months immediately after tillage, planting, fertilization, intense precipitation, and irrigation. The CH4 flux varied little, except for some peaks in the first year. Cumulative annual CO2 flux was 19%-30% greater for CT than NT in 2019-2020 and 2020-2021, and 13% greater for CT than ST in 2020-2021. Cumulative N2O flux was 31%-36% greater for CT than ST in 2018-2019 and 2020-2021, but 33%-83% lower for sugarbeet than spring wheat in all years. Cumulative CH4 flux was 83% lower for CT than NT and 68% lower for sugarbeet than spring wheat in 2018-2019. The GHG balance was 15%-23% greater for CT than NT and ST in 2019-2020 and 2020-2021 and 31% greater under sugarbeet than spring wheat in 2018-2019. No-tillage can reduce GHG emissions compared to conventional tillage, and sugarbeet can reduce N2O emissions compared to spring wheat in sugarbeet-based crop rotations.