Early view

Yugi R. Ahadiyat, Ervina Mela, Ahmad Fauzi

Abstract

The objective of this study was to determine the effect of organic fertilizer application and biochar plus low-dose synthetic fertilizer application on physiological characteristics and purple sweet potato yield. A factorial Randomized Block Design consisted of two factors: biochar plus a dose of 8 t/ha, viz. biochar, biochar+liquid organic fertilizer (LOF), biochar+azolla, and organic fertilizers with a dose of 15 t/ha, viz., no organic fertilizer, goat organic fertilizer, and cow organic fertilizer. Synthetic fertilizer of N, P, and K was applied at a low dose of 50% of the recommendation. The physiological variables observed were stomata density and stomatal opening width, leaf chlorophyll content, and total soluble solids (°Brix). Yield components were observed on tuber diameter and length, tuber weight per plant, and harvest index. Stomatal density, stomatal opening width, and total soluble solids were not improved due to the application of biochar and organic fertilizer. In general, the application of organic fertilizer in combination with biochar, could increase chlorophyll contents in leaves. However, the application of organic fertilizer or the enrichment of biochar with LOF and azolla failed to increase sweet potato yields. This result indicates that local cultivar of purple sweet potato has low response to organic fertilization and biochar application under reduced synthetic fertilizers.

Keywords

Azolla, biochar, liquid organic fertilizer, organic fertilizer, sweet potato

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