The Effect of P₂O₅ Fertilizer, Zeolite, and Volcanic Soil Media from Different Altitudes on the Soil Mineral, Growth, Yield, and Asiaticoside Content of Centella asiatica L.

Centella asiatica is an herbal plant with many health benefits due to the content of asiaticoside compounds. Factors affecting asiaticoside content are altitude, soil texture, and soil nutrient status. This research aimed to identify the effect of zeolite, P₂O₅ fertilizer, and soil media from different altitudes on C. asiatica. The research was conducted in a greenhouse from August 2017–June 2018. The experimental design was a factorial, completely randomized design with three factors and four replications. The first factor was soil media that originated from 100, 450, and 900 m above sea level (asl), the second factor was the dose of P₂O₅ fertilizer (0, 27, 54, and 81 kg ha⁻¹), and the third was the dose of zeolite (0, 3, and 6 t ha⁻¹). The results showed that applying zeolite minerals at all altitudes increased nutrient availability and soil cation exchange capacity (CEC) by up to 70%. The novelty of this study is that the soil from an altitude of 900 m asl, with a P₂O₅ fertilizer dose of 54 kg ha⁻¹, has a loamy sand soil texture and produces the highest asiaticoside content (3.61%) and the largest plant dry weight (19.24 g). These results did not significantly differ from those obtained from the soil 450 m asl with a sandy loam soil texture (the most suitable soil texture for C. asiatica), that is 3.37% asiaticoside and 19.87 g plant dry weight. This study concluded that C. asiatica could develop in loamy sand soil by giving it 54 kg ha⁻¹ P₂O₅ fertilizer.