Effect of biochar on sweet corn and soil salinity under conjunctive irrigation with brackish water in coastal saline soil

Coastal areas of Eastern China possess substantial salt-affected lands and brackish water for agriculture usage. A novel method using biochar and conjunctive irrigation was conducted to explore the reliable utilization of these low-quality resources. Sweet corn (Z. mays L. saccharate) was grown in a coastal saline soil amended with biochar (0 and 5%). Conjunctive irrigation was carried out by alternately applying brackish water (non-saline, 2, 6, 10 dS m−1) and freshwater at the vegetative and reproductive phase. Biochar application improved sweet corn photosynthetic performance and mitigated oxidative damage as well as salt stress, further resulted in higher production and marketable value. Meanwhile, biochar amendment facilitated the availability of saline irrigation during salt sensitive stages, promoting the conjunctive irrigation with brackish water for the coastal reclamation. In addition, more salts were removed out due to biochar after leaching, and the addition of biochar reduced the salinity of the soil profile during conjunctive irrigation. In general, under conjunctive irrigation, biochar application led to enhanced growth of sweet corn and favorable salinity control in the soil profile. However, further long-term field studies should be conducted to evaluate the complex effects of biochar for agricultural production using low-quality soil and water resources in coastal regions.