Abstract. Degradation of tropical peats is a global concern due to large Carbon emission and loss of biodiversity. The degradation of tropical peats usually starts when the government drains and clears peat forests into open peats used for food crops, oil palm and industrial timber plantations. Major properties of tropical peat forests are high in Water Contents (WC), Loss on Ignition (LOI) and Total Organic Carbon (TOC), and low in peat pH, Dry Bulk Density (DBD), and Total Nitrogen (TN). In this study, we investigated impacts of drainage and land use change on these properties. We collected peat samples from peat forests, logged over peat forest, industrial timber plantation, community agriculture, and oil palms. We used independent t-tests and oneway ANOVA to analyze mean differences of the research variables. We found that peat pH, DBD, and TN tend to increase. A significant decrease of C/N ratio in oil palm and agriculture sites importantly denotes a high rate of peat decompositions. Water contents, LOI, and TOC are relatively constants. We suggest that changes in pH, DBD, TN and atomic C/N ratio are important indicators for assessing tropical peat degradation. We infer that land use change from tropical peat forests intoCorrespondence to: G. Z. Anshari (gzanshari@live.untan.ac.id) cleared and drained peats used for intensive timber harvesting, oil palms and industrial timber plantations in Indonesia has greatly degraded major ecological function of tropical peats as Carbon storage.

Production of cellulase by Aspergillus niger was carried out by growing the cultureson sago waste. Sago waste contains cellulose that has not been used optimally. Cellulose is a polysaccharide consisting of glucose monomers linked by β-1,4glycosides bonds. Glycoside bonds in cellulose can be enzymatically hydrolyzed into glucose with cellulase enzymes. Solid fermentation used to produce cellulase on sago waste as substrate was influenced by pH (3 to 6), moisture content (40% to 85%), and fermentation time (4 to 10 days). Products of the cellulase enzyme activity was measured by phenolsulfuric acid method. The results showed that the highest cellulase enzyme activity was 0.172 U/mL obtained at 85% moisture content, pH 5, and 8 days of fermentation time. ABSTRAKProduksi enzim selulase oleh Aspergillus niger pada ampas sagu telah dilakukan. Ampas sagu adalah salah satu bahan yang mengandung selulosa di mana ampas sagu belum dimanfaatkan secara optimal. Selulosa merupakan polisakarida yang terdiri atas monomer glukosa yang dihubungkan oleh ikatan β-1,4-glikosida. Ikatan glikosida pada selulosa dapat dihidrolisis menjadi glukosa secara enzimatik dengan enzim selulase. Fermentasi padat digunakan untuk menghasilkan enzim selulase pada substrat ampas sagu yang dipengaruhi oleh faktor pH (3 sampai 6), kadar air (40% sampai 85%) dan waktu fermentasi (4 sampai 10 hari). Produk aktivitas enzim selulase diukur dengan metode fenol-asam sulfat. Hasil penelitian menunjukkan bahwa aktivitas enzim selulase tertinggi adalah 0,172 U/mL yang diperoleh pada kadar air 85%, pH 5, dan waktu fermentasi 8 hari.

Hydrophobic lignin’s character is used as the base of lignin usage as the binder in the urea fertilizer tablet. Lignin was isolated from black liquor of pulp and paper with palm empty bunch materials. Sulfonation of lignin isolate produced lignin sulfonate. Acetylation of lignin isolate produced lignin acetate. Lignin, lignin sulfonate and lignin acetate analyzed its solubility showed that lignin has no solubility in water. Therefore, urea fertilizer need to be modified by lignin. Nitrogen concentration of tablet lignin – urea with variation of lignin percentage 1,2,3,4 and 5 % examined with Kjehdahl method, produced nitrogen concentration in average 43%. Binding lignin isolate with percentage of 1 – 5 % to commercial urea fertilizer formed lignin – urea tablet. Its solubility test showed that lignin – urea formation will dissolve in 96 ; 137 ; 435 ; 759 ; 625 seconds, respectively. As control was commercial urea fertilizer with solubility’s time is 142 seconds.

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