Optimum Dosage of Enriched Biochar and Activated Charcoal in Increased Nitrogen, Phosphorus, and Potassium in Inceptisol Soils

Abstract This study explored the use of enriched biochar and activated charcoal as soil amendment materials to increase the nitrogen (N), phosphorus (P), and potassium (K) content in Inceptisol soil. Inceptisol is known to have low fertility which limits plant productivity. The two most common types of agricultural waste in Indonesia, rice husks and oil palm empty bunches (OPEB), have great potential to be used as soil amendments. These two materials are used as Biochar and activated charcoal, to be incubated in Inceptisol soil from the Kertasari area, Bandung Regency. The experiment aims to increase the availability of a major macronutrient, NPK, through the improvement of soil physical, chemical, and biological properties by Biochar and OPEB. An experimental method was applied, with a non-factorial Complete Randomized Design (RAL) experiment for as many as 11 treatments. The treatments tested were: enriched biochar with silica at 5 level of doses; activated charcoal at 5 level of doses; and control treatment (without biochar and activated charcoal). Results of the experiment showed a significantly different response of soil NPK levels to the treatment. The optimum dosage for enriched biochar in increasing total-N, P-available, and K-available is 4.37 tons/ha; 1.68 tons/ha; and 2.17 tons/ha. Meanwhile, the optimum dose of activated charcoal for the same parameter consecutively is 2.51 tons/ha; 1.91 tons/ha; and 2.29 tons/ha.