Improved Nitrogen Starter Fertilizer Strategy (Method and Level) for Field Grown Iceberg Lettuce (Lactuca sativa)

The paper presents three preliminary trials of a study with the aim to find a way to reduce total amounts of nitrogen applied in iceberg lettuce (Lactuca sativa) production without reducing the yield and quality by the use of a starter fertilizer strategy. The trials consisted of a fertilizer experiment, a demonstration plot and a trial in climate chamber conditions. Levels, total amounts and methods of nitrogen fertilizer application were compared. Low to medium levels of nitrogen added as placed starter fertilizer resulted in equal yield and lettuce quality compared to high levels and broadcast application. This means that the total amount of nitrogen fertilizer can probably be lowered and thereby the risk of nitrogen leaching from the field. No statistically significant reduction in yield or quality between broadcast and placed fertilizer treatments were found, so the placed starter fertilizer method seems promising, but need to be further tuned for Swedish climate conditions