Ashara Pengnoo, Wanna Leowarin, Nisakorn Koedsub, and Mana Kanjanamaneesathian

pp. 1 - 8

Abstract

Mesocarp fiber of oil palm, sludge cake from frozen seafood factory, rick husk and organic fertilizerwere mixed with a soil and incubated for 0, 15, 30, 45, 60, 75 and 90 days in plastic pots. At the end of eachincubation period, NH⁺₄-N and NO^-₃-N contents were determined by MgO-Devada alloy steam distillationmethod. N-mineralization differed depending upon incubation period and types of organic amendment. At60 days of incubation, N-mineralization of the amended soil had increased slightly. NO^-₃-N content was higherthan NH⁺₄-N content at all incubation periods especially in the soil amended with of the mesocarp fiber of oilpalm. The soil inoculated with Sclerotium rolfsii had higher rates of N-mineralization than the soil withoutS. rolfsii with the exception of the soil amended with mesocarp fiber of oil palm at 5 g/kg. soil and rick huskduring 60-90 days of incubation period. NO^-₃-N, was the dominant product of N-mineralization in soil bothadded with S. rolfsii and without S. rolfsii .