Using seaweed base organic fertilizer as yield booster at volcanic soil: effect on soil quality and yield of Patchouli (Pogostemon cablin)

Patchouli (Pogostemon cablin Benth.) is a bushy herb native to the tropical region of Asia, and now cultivated for its essential oil usually used in perfume manufacturing. It also widely used throughout the world as treating skin conditions, relieving depression, controlling appetite, and antifungal agents. It also cultivated commercially in Tawau, Sabah for exporting purposes with average oil production up to 26-29 mt per acre in 2016. As they enter the second and third harvesting cycle, the yield started to decline and reach 2.6 mt of oil per acre. This drop-in yield is thought to be either due to soil variabilities, low nutrient levels in volcanic soil, and also diseases. Soil nutrient analysis and leaf coloration patterns are studied before conducting the study. Seaweed extract, banana peel, the mixture of Seaweed extract and banana peel, and pre-formulated 12-12-12 (N-P-K) organic fertilizer (PFF) fertilizer treatments were engaged in the Patchouli plot field experiment. Besides, the agronomical practice for the cultivation of Patchouli is well studied or documented. The pre-study showed that the study plot has a very low conductivity level, a very low level of organic Carbon and low Cation Exchange Capacity (CEC) level. Meanwhile, there were no diseases or nematode occurrences in the area. Plant height, soil pH, and soil conductivity were studied with all the four treatments that have shown a positive significant impact compared with standard estate practice. The treatments using seaweed and seaweed mixture had the highest significant level for soil conductivity with the conductivity improve from 43 to 480 micro Siemens (μS/cm) but it reduces the soil pH. Whereas, plant height data analysis showed that the seaweed mixture was significantly different compared with other treatments at a 0.05 level. Hence, we recommend the Patchouli plantation to use organic fertilizers especially seaweed-based since it is cheap and easily available in Sabah.