Silicon fertilizer increased potato drought tolerance and reduced soil N2O emissions in two Danish soils at field scale

Potatoes, with their small, shallow roots, are one of the most drought-sensitive crops. Silicon (Si) fertilizers have the potential to increase the drought tolerance of potatoes by modulating soil and plant properties. We investigated the effect of Si fertilizers on potato production and greenhouse gas emissions (N₂O and CH₄) under drought stress. The experiment was conducted on 2 soils (orthic haplohumod-sand and typical Agrudalf-clay) with drought intensity as main plot (acute drought and severe drought) and Si fertilizers as split plots (amorphous silica-ASi, diatomaceous earth-DE and no-Si addition-Control). For drought intensity treatments, acute drought had higher total yields compared to severe drought, while Si fertilizer treatments (ASi and DE) had higher total yields as well as higher soil moisture and leaf P content compared to the Control in both soils. Overall, Si-based fertilizers (ASi and DE) significantly reduced cumulative N₂O emissions in both sand and clay soils compared to Control treatments. More specifically Si-based fertilizers recorded an average reduction of 31% in N₂O emissions compared to Control. For CH₄ emissions, Si-based fertilizers led to an 8% increase in CH₄ uptake in clay soils and a 3% increase in sand soils (with DE) compared to Control, although these values were not significant. Our results indicate that, at field scale, Si fertilization has the potential to be a sustainable solution for maintaining potato production while reducing agricultural N₂O emissions under drought stress in Denmark.