Application of Rice Husk Charcoal on Remediation of Acid Soil

Abstract

About 1 million tons of waste rice husk are generated in Taiwan each year. Rice husk has high concentrations of nutrients, such as silicon and potassium. However, it is not decomposed easily because it contains over 70% of cellulose and lignin and hence it is not suitable to be added into soil. In this study, a large quantity of rice husk is carbonized by vertical type continuous carbonization furnace without the presence of oxygen. After it is carbonized, it becomes rice husk charcoal (RHC) and vinegar (RHV). We have found that the addition of RHC carbonized at 600 and 700°C to soil can increase the soil’s concentrations of calcium, magnesium, potassium and silicon as well as its pH value (i.e., lowering its acidity level). Therefore, RHC is a great soil modifier because it can lower the soil’s acidity and increase the soil’s nutrients. According to our experiments, the pH values of the mixtures in different ratios exhibited an increasing and steady of final condition in the 80-day period. The reason was that the CEC (cation exchange capacity) of the mixtures were increased, the specific surface areas of the mixtures increased and the mixtures’ acidity levels were lowered. Therefore, the incorporation of RHC in the soil would benefit the soil on a long-term basis.

Effects of Rice Husk Biochar on Carbon Release and Nutrient Availability in Three Cultivation Age of Greenhouse Soils

“…Six RHB were collected for this study, including RHB-A (pyrolyzed at >500 • C) from Hualien District Agricultural Research and Extension Station, RHB-B (600 • C) and -C (700 • C) from Industrial Technology Research Institute (ITRI) Southern Region Campus [30], RHB-D and -E (both estimated to be pyrolyzed at <350 • C) from a market, and RHB-F (>500 • C) from a local farmer. RHB-A, -B, -C, and -F were slow pyrolyzed (30 min for A and F, 2~3 h for B and C) and carbonized separately by a horizontal (for A and F) or vertical (for B and C) continuous carbonization furnace without the presence of oxygen [30], but the commercial product RHB-D and -E could be produced in the open air by means of smoldering after burning. Raw RHB was used in the study without being ground into a mesh of <2 mm for analysis, except for elemental analysis.…”

Soil aggregate stability and carbon fractions in soils containing organic matter additions in intensive greenhouse vegetable fields

“…These results confirm the effectiveness of rice husks amendments to increase soil aggregate stability in the intensively managed greenhouse soils. Rice husks have been shown to improve soil physical properties (Chien et al, 2011;Anikwe 2000). This may be the result of the large specific surface area that can alter the total number of pores per volume and increase the bulk density (Pratiwi et al, 2016).…”

“…This may be the result of the large specific surface area that can alter the total number of pores per volume and increase the bulk density (Pratiwi et al, 2016). This pore size distribution can directly affect soil structure development (Chien et al, 2011).…”