Charred bark of Acacia mangium (bark charcoal), which is made of wood waste from pulp production, was applied as soil amendment for the cultivation of maize, cowpea and peanut to examine its effects on crop yield and soil chemical properties in South Sumatra, Indonesia. The yields of maize and peanut significantly increased after the application of bark charcoal under a fertilized condition in an infertile soil environment. In addition, increases in the root amount and colonization rate of arbuscular mycorrhizal (AM) fungi after bark charcoal application were also observed in maize. In general, the application of bark charcoal induced changes in soil chemical properties by increasing the pH value, total N and available P 2 O 5 contents, cation exchange capacity, amounts of exchangeable cations and base saturation, and by decreasing the content of exchangeable Al 3+ . The amelioration of the soil chemical properties could be effective in highly weathered infertile tropical soils. The application of charcoal in agriculture is expected to lead to the formation of a carbon sink in soil and to increase crop yield because it has been suggested that charcoal is highly resistant to abiotic and biotic degradation, even in a soil environment.

Abstract. In Asian countries, people have a long history of using rice husk charcoal or wood ash as an agricultural soil amendment, but evidence of this has been long obscured. Since the 1980s, microbiological studies, mainly on symbiotic organisms, have been performed in Japan. Charcoal is a porous material with high water and air retention capacities and high alkalinity. Therefore, it stimulates root growth and enhances the infection of various symbiotic microbes to plant partners. The use of carbonised materials in agriculture, forestry, and construction will contribute to the sustainability of crop production, soil conservation, and carbon sequestration. Biochar-related research accumulated mainly in Japan is reviewed.

The current study was initiated to evaluate the potential of sugar saps from nipa (Nypa fruticans) palm as sustainable feedstock for ethanol production. Nipa palms managed as plantations on four sites was chosen for this study with palms within 8 to 100 years of age. All palms studied were found to have the potential to produce sugar saps from 0.4 to 1.2 L d-1 per palm. Further chemical characterization of its saps gave a total composition of 159 to 214 g kg-1 mainly composed of sucrose, glucose and fructose. In addition, the elemental analysis gave 5 g kg-1 of inorganics with Na, K and Cl being its main inorganic elements. Preliminary batch fermentative assays using Saccharomyces cerevisiae showed that nipa saps can be converted to ethanol within 30 to 48 h in conditions with and without nutrient supplementation. Furthermore, the fermentation trends were similar to sugarcane sap with high ethanol conversions up to 96.9% and 95.5% achieved for both nutrient conditions. Further analysis on inorganic elements before and after fermentation showed that specific elements of Mg, Ca, P and S were significantly reduced and could have assisted the fermentation. Based on the results obtained from sap collection, chemical characterization and fermentation, the ethanol potential from nipa planted at a density of 1000 ha-1 would range from 4550-9100 L ha-1 y-1. Conclusively, nipa sap showed some interesting characteristics which makes it a potential feedstock for ethanol production.

biochar, biomass utilization, carbonization, carbon sequestration, carbon sink,

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