An incubation experiment was conducted to examine the effects of the phosphorus (P) application o... more An incubation experiment was conducted to examine the effects of the phosphorus (P) application on nitrous oxide (N2O) and nitric oxide (NO) emissions from soils of an Acacia mangium plantation in Indonesia. The soils were incubated with and without the addition of P (Ca[H2PO4]2; 2 mg P g soil)−1) after adjusting the water-filled pore space (WFPS) to 75% or 100%. The P addition increased N2O emissions under both WFPS conditions and NO emissions at 75% WFPS. Some possible mechanisms are considered. First, the P addition stimulated nitrogen (N) cycling, and N used for nitrification and/or denitrification also increased. Second, the P addition could have relieved the P shortage for nitrifying and/or denitrifying bacteria, producing N2O and NO. Our results suggest that the application of P fertilizer has the potential to stimulate N2O and NO emissions from Acacia mangium plantations, at least when soils are under relatively wet conditions.
Colonization of leaf litter by ligninolytic fungi and relationships between mass loss and chemica... more Colonization of leaf litter by ligninolytic fungi and relationships between mass loss and chemical qualities of surface leaf litter were examined in Acacia mangium plantations and adjacent secondary forests in southern Sumatra Island, Indonesia. Leaves were collected from eight A. mangium plantations of different ages and three secondary forests. Partly decomposed leaves beneath the surface leaf litter were used to measure the bleached area which indicated colonization by ligninolytic fungi. Surface leaf litter was used to measure initial chemical content and subjected to the pure culture decomposition test. The bleached area was greater in secondary forests than in A. mangium plantations. Nitrogen content was higher in all the A. mangium plantations than in the secondary forests, and acid unhydrolyzable residue (AUR) content was generally higher in the A. mangium plantations than in the secondary forests. The bleached area of leaf litter was negatively correlated with nitrogen content of surface leaf litter at all sites, indicating an inhibition of the colonization by ligninolytic fungi of leaves with higher nitrogen content. In a pure culture decomposition test inoculating a ligninolytic fungus to surface leaf litter, mass loss of leaves was negatively correlated with AUR content of surface leaf litter. Mass loss of leaves and AUR was not significantly related to nitrogen content. These results suggested that higher nitrogen content in A. mangium leaf litter had a negative effect by colonization of ligninolytic fungi, but the effect of high N in A. mangium leaf litter on the decomposition of leaf litter and AUR remained unsolved.
... Soil pH (H 2 O) was measured using a glass electrode in a suspension of 10-g soil and 25-ml d... more ... Soil pH (H 2 O) was measured using a glass electrode in a suspension of 10-g soil and 25-ml distilled water. Total C and N contents of soil were determined using a N/C analyzer (JM1000CN;J-Science Lab Co., Ltd., Kyoto, Japan) on air-dried soil samples. ...
An incubation experiment was conducted to examine the effects of the phosphorus (P) application o... more An incubation experiment was conducted to examine the effects of the phosphorus (P) application on nitrous oxide (N2O) and nitric oxide (NO) emissions from soils of an Acacia mangium plantation in Indonesia. The soils were incubated with and without the addition of P (Ca[H2PO4]2; 2 mg P g soil)−1) after adjusting the water-filled pore space (WFPS) to 75% or 100%. The P addition increased N2O emissions under both WFPS conditions and NO emissions at 75% WFPS. Some possible mechanisms are considered. First, the P addition stimulated nitrogen (N) cycling, and N used for nitrification and/or denitrification also increased. Second, the P addition could have relieved the P shortage for nitrifying and/or denitrifying bacteria, producing N2O and NO. Our results suggest that the application of P fertilizer has the potential to stimulate N2O and NO emissions from Acacia mangium plantations, at least when soils are under relatively wet conditions.
Colonization of leaf litter by ligninolytic fungi and relationships between mass loss and chemica... more Colonization of leaf litter by ligninolytic fungi and relationships between mass loss and chemical qualities of surface leaf litter were examined in Acacia mangium plantations and adjacent secondary forests in southern Sumatra Island, Indonesia. Leaves were collected from eight A. mangium plantations of different ages and three secondary forests. Partly decomposed leaves beneath the surface leaf litter were used to measure the bleached area which indicated colonization by ligninolytic fungi. Surface leaf litter was used to measure initial chemical content and subjected to the pure culture decomposition test. The bleached area was greater in secondary forests than in A. mangium plantations. Nitrogen content was higher in all the A. mangium plantations than in the secondary forests, and acid unhydrolyzable residue (AUR) content was generally higher in the A. mangium plantations than in the secondary forests. The bleached area of leaf litter was negatively correlated with nitrogen content of surface leaf litter at all sites, indicating an inhibition of the colonization by ligninolytic fungi of leaves with higher nitrogen content. In a pure culture decomposition test inoculating a ligninolytic fungus to surface leaf litter, mass loss of leaves was negatively correlated with AUR content of surface leaf litter. Mass loss of leaves and AUR was not significantly related to nitrogen content. These results suggested that higher nitrogen content in A. mangium leaf litter had a negative effect by colonization of ligninolytic fungi, but the effect of high N in A. mangium leaf litter on the decomposition of leaf litter and AUR remained unsolved.
... Soil pH (H 2 O) was measured using a glass electrode in a suspension of 10-g soil and 25-ml d... more ... Soil pH (H 2 O) was measured using a glass electrode in a suspension of 10-g soil and 25-ml distilled water. Total C and N contents of soil were determined using a N/C analyzer (JM1000CN;J-Science Lab Co., Ltd., Kyoto, Japan) on air-dried soil samples. ...
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Papers by Agus Wicaksono