Saline-alkali soil amended with biochar derived from maricultural-solid-waste: Ameliorative effect and mechanism

At present, it is estimated that approximately 800 million hectares of arable land worldwide is saline-alkali soil, which has become one of the major limiting factors restricting global agricultural productivity. Meanwhile, the residual food and excreta of mariculture animals, accompanied by potential eutrophication pollution, remain an unresolved issue due to salinity. In this study, the ameliorative effects of biochar (BC700) prepared from maricultural-solid-waste on the biological properties and physicochemical of saline-alkali soil and Salicornia europaea L growth were investigated. Supplements of 1, 3 and 5% BC700 significantly increased the total nitrogen, available phosphorus, available potassium and organic carbon in soil by 2.00-68.30%, 26.74-64.96%, 7.74-52.53% and 3.43-64.96%, respectively. And BC700 significantly reduced soil pH. This occurred with enhanced soil urease, sucrase and alkaline phosphatase activities and alterations to the bacterial community structure, thus improving P and N cycling and the soil physicochemical properties. In addition, BC700 has weakened the competition between saline soil microorganisms and also changed the key species of microbial networks. Co-utilization of BC700 and S. europaea cultivation could increase the stability of the soil microbial community while the growth of the plant was significantly promoted by 19.8-25.4%. Supplements of 3% BC700 are recommended as an eco-friendly and effective treatment for the recycling of mariculture wastes for the improvement of saline-alkali soils.