Response of Sugar Beet to Nitrogen Rate While Shifting from Conventional Tillage to Conservation Tillage.

Conventional tillage (CT) is still widely used by sugar beet growers, which consists of five or more passes across a field for plowing, leveling, and hilling. This intensive soil tilth has many unintended consequences for soils and the environment such as loss of organic matter, increased soil erosion, pesticide runoff, and soil compaction. Moreover, removal of all crop residue exposes sugar beet seedlings to high winds that can severely affect sugar beet establishment. Conventional tillage is also expensive, requiring large labor and fossil energy inputs. Therefore, shifting from CT to reduced tillage practices such as strip-till (ST) and no-till (NT) has drawn attention. Nutrient management, especially nitrogen (N), needs to be optimized when tillage system is changed. A field experiment was conducted in 2016 and 2017 in Sidney Montana to evaluate the performance of sugar beet under CT vs. ST and NT under various rates of N (0, 56, 112, 168 kg ha^-1). Results indicated that tillage had a significant effect only on aboveground biomass and plant stand in 2016. Aboveground biomass and plant stand were higher in NT compared to CT and ST. No significant difference was observed between tillage systems in terms of root yield, sucrose percent, and sucrose yield. This is highly important since NT provided economic benefits (lower cost, less labor, less fuel consumption) as well as ecosystem services (less soil erosion, soil compaction, etc.) while producing similar yield as CT. Optimized nitrogen fertilization for sugar beet under various tillage systems will be presented.

Keywords: Beta vulgaris; energy in agroecosystems; No-till; Soil erosion; Strip-till.