Browsing by Author "Härkönen, Toni"

Aim of this thesis was to study the quantity of nitrous oxide (N2O) emissions from pea in a multiple-year experiment in Haltiala, Helsinki, in growing seasons 2020–2022 in Leg4Life project’s field trial (2020–2024). The experiment was conducted as a randomized complete block design (RCBD) with four replicates. There were ten (10) different treatments including one (1) fallow. Treatments were different pea crop rotations with fertilized monoculture grown pea (20 kg N ha-1) and fertilized monoculture grown oat (90 kg N ha-1) as a control treatments. Treatments were 1 (fallow – fallow – fallow), 2 (pea 20– pea 20 – pea 20), 3 (oat 90 – oat 90 – oat 90), 4 (pea 20 – spring wheat 90 – pea 20), 5 (pea-rapeseed 20–20 – oat 0 – pea 20), 6 (pea-rapeseed 20–20 – oat 90 – pea 20), 7 (pea 20 – winter wheat 90 – rapeseed 90), 8 (pea 20 – rapeseed 0 – spring wheat 90), 9 (pea 20 – rapeseed 90 – spring wheat 90) and 10 (pea 20 – oat 90 – rapeseed 90). Nitrogen fertilization levels were either 20, 40 or 90 kg ha-1. Gas emission samples were measured in field from closed chambers by taking three samples in 20 minutes interval from treatments 1, 2, 3, 5, 6, 8 and 9. Samples were analysed in gas chromatograph. Statistical analyses were made by analysis of variance (ANOVA). Statistically significant differences in means were located by using a t-test (LSD) Results were not statistically different from each other except fallow (treatment 1) in 2020 and spring wheat (treatment 8) in 2022 which caused statistically significant higher N2O-emissions compared to other treatments. Cumulative N2O-emissions from three years were not statistically different from each other except treatment 8 (pea 20 – rapeseed 0 – spring wheat 90), which differed all other crop rotation treatments but not treatment 1 (fallow – fallow – fallow). Cultivation of pea did not cause significantly higher N2O-emissions than oat or spring wheat. Catch crop did not have effect on emissions either. Dry matter and nitrogen yield-scaled N2O-emissions from pea treatments were not significantly higher when compared to other treatments except in 2021 when dry matter yield-scaled N2O-emissions from pea (treatment 2, pea 20) were significantly higher than those in oats (treatments 3, 5 and 6, oat 90, oat 0 and oat 90). Dry matter yield-scaled N2O-emissions were 1.0 and 0.3 g N2O-N kg-1 aboveground biomass respectively.