Influence of Planting Distances, Boron Application and Varying Fertilizer Levels on the yield Performance of Shallot (Allium Cepa var. Aggregatum) Across Season in Ilocos Norte, Philippines

Shallots are gaining importance in the Ilocos region, due to their culinary uses in traditional cuisine, medicinal properties, and export potential. However, the reduction of inherent soil fertility and the manifestation of multiple nutrient deficiencies have led to low yields which is 13.70% lower than the national average. Consequently, researchers and farmers are aware in the improvement of shallot production in the region. This study, conducted from March, 2023 to February, 2024, at Mariano Marcos State University using a Strip-Split-Plot design with three replicates and analyzed using STAR. Planting distances as vertical plot, boron application as horizontal plot, and fertilizer level as the subplot. The study aimed to evaluate the influence of planting distances on yield performance of shallots, and to develop better nutrient management strategies for optimal shallot production. To optimized shallot productivity per land unit area, particularly during the off-season, it is recommended to adopt closer planting distances of 15cm x 10cm combined with the application of 30-30-30 kgha⁻¹ NP₂O₅K₂O and 5 tha⁻¹ of organic fertilizer. This technique has been shown to produce higher yields, reaching up to 17.39 tha⁻¹. Additionally, pure organic fertilizer application at a rate of 7.5 tha⁻¹ during the off-season is also recommended, as it has demonstrated high yields of 16.12 tha⁻¹ when using the same planting distance of 15 cm x 10 cm. This approach not only increases yield but also improves soil health, making it a sustainable option for long-term cultivation. For the regular season, planting distances of 20 cm x 10 cm and 15 cm x 15 cm, applied with 60-60-60 kg ha⁻¹ NP₂O₅K₂O and 2.5 tons ha⁻¹ of organic fertilizer, are recommended, as they have produced yields of up to 29.4 tons ha⁻¹. While pure inorganic fertilizer results in high yields during the regular season, a combination of organic and inorganic fertilizers is preferred to enhance soil health and prevent soil d