Combined application of rice husk biochar and fly ash improved the yield of lowland rice

The effects of rice husk biochar (BC) and coal fly ash (FA) on growth and yield of rice and soil properties were investigated in a lowland rice soil. All growth parameters and yield were positively influenced by the integrated application of BC, FA and chemical fertilisers compared with sole application of chemical fertilisers. Yield increase was 16.4% when BC+FA was applied together with 50% of the recommended dose of nitrogen (N) compared with the recommended dose of N, phosphorus and potassium (NPK). Post-harvest soil analysis suggested that BC and FA both act as a supplier, as well as a reservoir of nutrients. Accumulation of heavy metals in soil and plant parts after harvest was below the toxicity threshold for plants and humans. There was also no significant change in microbial population compared with the initial soil. Therefore, combined application of BC and FA supplemented with chemical fertilisers could be recommended to improve soil fertility and crop productivity without affecting the soil quality.