NITRIFICATION AND DENITRIFICATION RATES OF SOIL UNDER BLACK PINE STAND (Pinus thunbergii) IN DIFFERENT AGE ON SANDY COASTAL AREAS OF SHONAI, YAMAGATA, JAPAN

MEILANIA NUGRAHENI, Dr.Ir. Haryono Supriyo, M.Agr.Sc.; Daryono Prehaten, S.Hut, M.Sc.

2016 | Skripsi | S1 KEHUTANAN

Kosong

Understanding changes in soil N cycling with stand development is critical for forest management as tree growth is affected by soil N availability. Nitrification is one of the key processes causing N loss through denitrification, which is the process of gaseous N loss from an ecosystem. Soil reaction (pH), moisture, temperature, and organic matter are the most affecting factors for nitrification and denitrification in the soil. Nitrification and denitrification rates may increase or decrease, depending on the stand type, stand age and the extent of disturbance imposed on the forests. The aim of this study is to find out the nitrification and denitrification rates of soil under black pine stand (Pinus thunbergii) by analyzing these activities during 4 weeks incubation. This study took place in black pine stand along sandy coastal areas of Shonai, Yamagata, Japan. Samples were taken in 23 locations with different ages. Experiment procedures were explained detailly in Cheng et al. 2004a, 2004b. During the experiment, the soil produced ammonium in large quantities (up to 300 mikrogram N g-1) , but only produced 3.09 mikrogram-1 nitrate during 4 weeks incubation. Same trend was occurred in denitrification. There was a slight fluctuation of nitrate. It might be due to the lack of nitrifier bacteria in the soil, since the pH in acid range (4-6) not suitable for nitrifier bacteria activities. Based on NH4+ and NO3- concentration in both nitrification and denitrification experiments, the result showed that this soil samples had high rates of mineralization and very low rates of nitrification and denitrification.

Kata Kunci : Nitrification, denitrification, black pine stand, sandy soil