The most popular fertilizer for foliar application is urea. Urea is a water-soluble nitrogen fertilizer that is quickly absorbed by plants. It is also relatively inexpensive and easy to use. Urea can be applied to plants as a foliar spray or as a side dressing. When applied as a foliar spray, urea is absorbed directly by the leaves and can provide a quick boost of nitrogen to plants. When applied as a side dressing, urea is absorbed through the roots and provides a more gradual release of nitrogen.
Sodium nitrate is a water-soluble nitrogen fertilizer that is also quickly absorbed by plants. However, sodium nitrate can be more expensive than urea and it can also increase the salinity of the soil.
DAP is a water-soluble phosphorus fertilizer that is not as quickly absorbed by plants as urea or sodium nitrate. DAP is also more expensive than urea or sodium nitrate.
Potassium chloride is a water-soluble potassium fertilizer that is not as quickly absorbed by plants as urea or sodium nitrate. Potassium chloride is also more expensive than urea or sodium nitrate.
In conclusion, urea is the most popular fertilizer for foliar application because it is inexpensive, easy to use, and quickly absorbed by plants.