Fine Root Biomass and Soil Chemistry in the 'Ome' Agroecosystem of Buton Karst, Indonesia

The "Ome" agricultural system in the karst region has unique characteristics that influence root biomass production and soil chemical properties based on the duration of land abandonment. This research aimed to investigate the relationship between the root biomass production and soil chemical properties of the Ome agricultural system in the karst land area of Central Buton. Method: This study employed a field survey method where soil sampling was conducted at three ages of "Ome," at 10-, 20-, and 40-years post-abandonment. Soil samples were collected using quadrats measuring 25 x 25 cm at a depth of 10 cm. The fine roots, which had been cleaned, were subsequently sorted into living roots (biomass) and dead roots (necromass) and then dried. The chemical properties of the soil analyzed include pH, CN, total N, P2O5, available P, NH4+, NO3, K, Ca, Mg, C, N, and Cation Exchange Capacity (CEC). Results: The pH and nitrate (NO3) parameters at the "Ome"age of 40 years are significantly greater than those at the other ages. Higher increases in pH and Nitrare at 40 years of land age indicated significant change in soil chemistry related to the stages of vegetation succession, thus accumulating litter that absorbs soil rich in K and Mg, which plays a role in increasing soil pH and will increase nitrogen in the soil. There are no significant differences observed at the ages of 10 and 20 years. Fallen "Ome" land is divided based on the degree of fallow, which varies the amount of fine root biomass, necromass, and total fine root mass. Fine root biomass is correlated with several soil characteristics, such as Ammonium (NH4+) Nitrate (NO3) and Carbon (C), which may or may not influence the fine root development. Conclusions: The potential of root biomass in the "Ome" agricultural system in karst areas is positively correlated with indices of soil chemical properties that may vary with different "Ome" abandonment durations. Keywords: Soil health, organic matter, soil chemistry, root biomas, nutrient cycling, root necromass