BIOCHAR AS A SOIL AMENDMENT TO IMPROVE CROP YIELD AND SOIL CARBON SEQUESTRATION

Biochar as a soil amendment has been reported to sequester carbon, increase retention of fertilizer derived nutrients for crop uptake and reduce leaching and run-off to ground and surface water; resulting in increased crop yields. In Malaysia rice husk biochar (RHB) has been available as a by-product of rice mills while recently, a biochar from oil palm empty fruit bunch (EFBB) has been produced. A study was initiated at the Universiti Putra Malaysia to determine the potential use of these biochars in improving crop yields, soil C sequestration and soil properties. Experiments on leafy vegetables were carried out to determine the effects of RHB application rates (0, 10, 15 and 20 t/ha) on the yield of Amaranthus viridis and Ipomoea reptans. Concurrently, experiments with sweet corn (Zea mays ‘Madu’) were also established in containers to determine the effects of application rates of RHB (0, 5, 10 and 15 t/ha) and EFBB (0, 10 and 15 t/ha) on crop performance, soil properties and total C for two crop cycles. Results show that application of RHB increased yield of Amaranthus viridis and Ipomoea reptans compared to the treatment without RHB. However, there was no significant difference in soil total C and pH between treatments applied with and without RHB. The effect of RHB on soil total C was probably masked by decomposition of the rice straw applied as mulching material. The experiments with sweet corn showed no significant effect of both biochar amendments on cob yield but there was significant increase in total dry matter weight, particularly in the second crop cycle. The soil total C content, pH and cation exchange capacity increased with application of EFBB.