Sugar kelp application for sustainable potato production in Prince Edward Island: Impacts on soil, greenhouse gas emissions, and yield

Abstract

Context

Sugar kelp (SK) is a promising organic fertilizer with the potential to enhance crop yield, improve soil health, and reduce environmental impacts. However, its specific effects on soil quality, crop productivity, and particularly its role in climate change mitigation are still not well understood.

Objectives

This study evaluated the effects of SK, as seaweed-based organic fertilizer, and its combinations with IF on soil health, emissions of CO₂ and N₂O, as well as CH₄ uptake, potato growth and yield during the 2023 and 2024 growing seasons in Prince Edward Island, Canada’s largest potato-producing province.

Methods

Field experiments were conducted over a two-year period (2023 and 2024). In 2023, treatments included: SK alone (2 tons ha^-¹), IF alone (meeting the full nitrogen (N) requirement), SK + IF (50 %-50 % N), and control (no fertilizer). In 2024, treatments were: IF alone, SK + IF (full N), SK + IF (80 % N), and control. The study measured soil organic matter, pH, P₂O₅, K₂O, Ca, Mg, Cu, Zn, S, Mn, Fe, Na, Al, and NO₃^-, along with the Normalized Difference Vegetation Index (NDVI), and potato yield. Soil emission of CO₂ and N₂O emissions, and soil CH₄ uptake were also measured using the Li-COR trace gas analyzer.

Results

Soil pH, organic matter, calcium, magnesium, and cation exchange capacity remained stable across treatments. Trace elements such as copper, iron, and zinc also showed minimal variation. However, the SK application significantly increased soil sodium concentrations in both years (p < 0.05). In 2024, nitrate (NO₃⁻-N) levels were significantly higher in the IF treatments than in the control. Cumulative CO₂ emissions and CH₄ uptake did not differ significantly among treatments in either year. IF-only treatments showed the highest cumulative N₂O emissions, whereas treatments combining SK with reduced IF significantly lowered cumulative N₂O emissions to levels similar to the control. These reduced-emission treatments maintained NDVI values and potato yields comparable to those of the full IF treatments, both of which outperformed the control.

Conclusions

These results suggest that combining SK with reduced IF can sustain potato yields while significantly lowering N₂O emissions. These findings highlight the potential of SK in sustainable fertilizer strategies; however, further long-term research and economic analysis are necessary to evaluate its broader viability in agriculture.