Silicon fertilizer increased potato drought tolerance and reduced soil N$_2$O emissions in two Danish soils at field scale

Silicon (Si) fertilization enhances drought tolerance, but its effectiveness under field conditions and drought intensities remains uncertain. Moreover, the role of Si in regulating greenhouse gas emissions is poorly understood. Therefore, we conducted a field experiment, to assess the effects of Si fertilization on potato yields and on N$_2$O and CH4 emissions under drought stress, considering both agronomic and environmental effects. The experiment was conducted on 2 soils (Orthic haplohumod-sand and Typical agrudalf-clay) with drought intensity as main plot (acute drought-AD and severe drought-SD) and Si fertilizers as split plots (amorphous silica-ASi, diatomaceous earth-DE and no-Si addition-control). AD treatments had higher yields than SD, due to higher soil moisture availability. In both soils, Si fertilizers (ASi and DE) produced higher yields associated with enhanced soil moisture and phosphorus content compared to the control. Si fertilizers significantly reduced cumulative N$_2$O emissions in both soils, with an average reduction of 31% compared to the control, likely due to altered denitrification processes. Our results indicate that, at field scale, Si fertilization has the potential to be a sustainable solution for maintaining potato production while reducing agricultural N$_2$O emissions under drought stress in Denmark.