Effect of different biochar sources on soil ionic composition under maize cultivation. Mean value of three replicates has been presented with bars showing standard error. Least significant difference was used for multiple comparisons under complete randomized design. NSC: non-saline control; SSC: saline-sodic control; OPB: orange peel biochar; WSB: wheat straw biochar; RHB: rice husk biochar; S: salinization.