Effects of particle size and application rate of rice-husk biochar on chemical properties of tropical wetland soil, rice growth and yield

Abstract

Besides unpredictable time and duration of flooding occurrence, low soil fertility has been another main agricultural issue at riparian wetland in Indonesia. The objective of this research was to determine the potential use of biochar in improving soil chemical properties, rice growth, and yields. Assessment on the effects of particle sizes (S) and application rates (R) of rice-husk biochar was executed through pot experiments in a greenhouse of Universitas Sriwijaya, Indonesia, from January to April 2017. The experiment was laid out in randomized block arrangement with three replications. S consisted of particle sizes 1 mm (S 1 ) and > 1 mm (S 2 ). R consisted of application rates at 1 t ha -1 (R 1 ), 2 t ha -1 (R 2 ), 3 t ha -1 (R 3 ), and 4 t ha -1 (R 4 ). Rice growth, yield, and growth analysis were measured during vegetative and generative stage. Soil chemical properties were analyzed after harvesting. Results indicated that application of biochar increased soil pH but did not affect cation exchange capacity (CEC), and availability of major soil nutrients. During vegetative stage, biochar application increased relative growth rate (RGR) and net assimilation rate (NAR) but decreased leaf are ratio (LAR). R 3 treatment significantly increased grain weight per panicle, number of filled spikelet, and weight of 1000 grains. Root and stem N content tended to be higher with biochar application. Application of biochar on riparian wetland soil exhibited some promising positive impacts on soil properties, growth, and yield of rice. However, a long term study on residual effects of biochar application in tropical riparian wetland needs to be pursued further for a more comprehensive understanding on this issue.