Effect of Sugar Kelp on Soil Health, Greenhouse Gas Emissions and Yield in Potato Cropping System

Abstract

Organic fertilizers, such as sugar kelp (SK), are gaining recognition as sustainable alternatives to inorganic fertilizers due to their ability to improve soil health and reduce environmental impacts. This study assessed the effects of SK and its combinations with inorganic fertilizer (IF) on soil health, greenhouse gas (GHG) emissions, and the growth and yield of potato crops during the 2023 and 2024 growing seasons in Prince Edward Island, which is Canada’s largest potato-producing province. In 2023, four treatments were implemented: SK alone at a rate of 2 tons per hectare, IF alone (which satisfied the entire nitrogen requirement), a combination of SK and IF (providing a 50%-50% nitrogen contribution), and a control group with no fertilizer. The following year, the treatments included IF alone, a combination of SK and IF (fully meeting the nitrogen requirement), a combination of SK and IF (fulfilling 80% of the nitrogen requirement), and a control. Chemical analyses of the soil indicated that pH, organic matter (OM), calcium (Ca), magnesium (Mg), and cation exchange capacity (CEC) remained consistent across all treatments. Trace elements, including copper (Cu), iron (Fe), and zinc (Zn), showed only minor fluctuations. However, the application of SK significantly raised soil sodium (Na) levels in both years (p < 0.05). In 2024, nitrate (NO₃⁻-N) concentrations were significantly elevated in IF treatments compared to the control. There were no significant differences in cumulative CO₂ emissions and CH₄ uptake among the treatments for either year. The fertilizer-only treatments recorded the highest cumulative N₂O emissions, while the treatments that combined SK with reduced IF resulted in significantly lower N₂O emissions, comparable to those observed in the control group. Notably, these reduced-emission treatments did not display significant differences in Normalized Difference Vegetation Index (NDVI) or potato yield compared to treatments that utilized full IF, which had significantly greater values than the control. In summary, the findings indicate that integrating SK with reduced IF can sustain potato yields while markedly decreasing N₂O emissions