Biochar (Carbonized Rice Husk)

Biochar is used as soil amendment to improve soil productivity, carbon storage, and filtration of percolating soil water (Lehmann and Joseph 2009). Libra et al (2011) have found it to have beneficial effects in increasing water-holding capacity, aeration and hydraulic conductivity, reduced tensile strength of hard-setting soils, and stimulating growth activity. A study of Haefele et al (2011) showed that application of untreated and carbonized rice husks increased total organic carbon, total soil N, C:N ratio, and available P and K, whereas high C:N ratio of carbonized rice husk (biochar) limits N availability, thereby slightly reducing grain yield. On a poor soil, which is identified as having low organic carbon, nitrogen content, base saturation, K availability, and cation exchange capacity; and dominated by sand, soil chemical and physical improvements increased yields by 16–35% with an amendment of 4.13 kg carbonized rice husk per square meter croping.