Abstract
Bentio
Heru Purwanto1, Akira Watanabe2, Jong Foh Shoon3, Ken-ichi Kakuda4, and Ho
Ando4
1: Faculty of Agriculture, Yamagata University, Tsuruoka, 997-8555, Japan, present
address: Faculty of Agriculture, Gadja Mada university, Yogyakarta, Indonesia
2: Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, 464-8601
Japan
3: PT. National Timber & Forest Product, Jl. Sultan Syarif Qasiim No. 81,
Pekanbaru, Indonesia
4: Faculty of Agriculture, Yamagata University, Tsuruoka, 997-8555 Japan
Peat land has been considered as an alternative type of land for agricultural
development especially in the tropics. In the present study, the N-supplying
capacity, one of the most important soil properties in terms of crop production,
of peat soils was examined. Ten peat soil samples were collected from Indonesia,
Malaysia, and Japan. Gross N mineralization in the soil samples was estimated
using a zero-order model, and kinetic parameters of mineralization were determined
using a simple type model. Soil organic matter composition was investigated
using 13C CPMAS NMR. Mineralization potential (N0), apparent activation energy
(Ea), and mineralization rate constant (k) ranged between 571-2445 mg kg-1,
281-8181 J mol-1, and 0.009-0.020 day-1, respectively. Although none of the
parameters showed a significant correlation with the soil C/N ratio, a negative
correlation was observed between the k value and the ratio of the proportion
of alkyl C in total C to that of O-alkyl C estimated by 13C CPMAS NMR. The
latter suggested that the k values were higher in the peat soils relatively
rich in readily decomposable organic matter including carbohydrates.
Key words: 13C CPMAS NMR, N mineralization parameter, organic matter composition,
peat soil