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Densification of biochar can reduce transportation and handling costs, as well as significantly decrease loss of biochar during soil application. Although the nutrient-rich biochar tablets may be a potential cost-effective slow-release fertilizer in soil, there is a lack of information on characterization of mixtures of rubber tree twigs and rice residues tablets with embedded NPK fertilizer. Objective of this work was to determine the physical and chemical properties of biochar tablets with and without embedded fertilizer. Biochar tablets were produced by blending of charred rice husk, rice straw, rubber tree twigs, and starch and followed by tableting. Their production with embedded fertilizer was similar to production process of tablets without it, except adding the NPK fertilizer to blending phase prior to tableting. Fourier-transform infrared spectra analysis indicates was utilized for determination of presence of ammonium and phosphorus substances in the biochar tablets with embedded fertilizer (BFs). The NPK fertilizer significantly increased tablet density and total contents of nitrogen, phosphorus, potassium, calcium and magnesium. The presence of higher amount of nutrients in BFs suggests that it could release nutrients for plant use.

The present study was undertaken to determine the weight loss of pots made of different ratios of biomaterials and banana peels. Two types of biodegradable pots were produced using different ratios of biomaterials (B) and banana peels (BP). The ratios of B to BP tested in this study were B50% : BP50% and B30% : BP 70%. The weight loss of biodegradable pot with ratio B30% : BP70% was significantly higher than biodegradable pot with ratio B50% : BP50% after the empty biodegradable pots were left to decompose on the ground for 60 days. This result suggests that higher content of banana peels increase the microbial decomposition of the biodegradable pot. On the contrary, the weight loss of biodegradable pot with ratio B50%:BP50% was higher when they were filled with soil and left to decompose on the ground for 60 days. This is probably due to the lower content of banana peels, what decreased the tensile strength of biodegradable pot filled with soil, making it highly decomposable in such manner. In terms of degradability, biodegradable pot with ratio B30% : BP70% is more appropriate than pot with ratio B50% : BP50%.