Enhancing Wheat Productivity in Salt-Affected Soils Using Traditional and Acidified Biochars: A Sustainable Solution

Soil salinity constitutes a significant threat to crops. Probably, adding some soil additives such as biochar could alleviate salt stress and , at the same time, improve soil characteristics. To test this hypothesis, crop residues were collected and subjected to pyrolysis to prepare normal biochar. Portions of this product were acidified with sulfuric acid, while the other portions were left non-acidified. Then, a pot experiment of a complete randomized design was established comprising 5 treatments, with three replicates each, i.e. either 5 or 10 g kg-1 of each of acid modified biochar and the non-acidified one, beside of the non-amended control soil (EC= 5.94 dS m-1) which was deemed a control one. Wheat was sown in all pots and soil moisture was sustained at field capacity using well water (EC = 0.59 dSm-1) throughout the duration of the experiment. After a period of approximately 50 days post-germination , proline and chlorophyll contents were assessed in shoots. At physiological maturity stage, whole plants were harvested and soil samples were collected from the rhizosphere of each pot. The plant stress osmoprotectant named proline decreased significantly in plants amended with biochar as if these plants suffer less from salinity stress. Moreover, plant biomass improved significantly due to biochar application, with superiority for the acidified one. This additive (acid-modified biochar) also augmented grain to shoot ratio; number of plants per pot, number of spikes per plant and plant height, while lessened root-to-shoot ratio. In this regard, the most significant enhancements in the aforementioned plant growth parameters were observed at the higher application rate of biochar, specifically 10 g kg-1. The improvements in plant growth parameters exhibited a substantial correlation with the concomitant increases in nitrogen, phosphorus, and potassium (NPK) uptake by the plants. Notably, K concentrations in the shoots were sufficiently high, suggesting a potential role in osmoregulation. On the other hand, no significant differences were detected in leaf chlorophyll (SPAD) among the investigated treatments. Concerning soil organic carbon content, a remarkable increase was noted in soil following the application of biochar, especially the non-acidified biochar when being applied at a rate of 10 g kg-1. Nonetheless, the latter application rate raised significantly soil salinity, while acid modified biochar declined soil EC. In conclusion, the improvements in characters of salt affected soils due to intensive cropping and enhancement of wheat growth as noted for the application of acidified biochar may, at times, be more effective than the effect of the soil amendment itself, which is remarked for application of non-acidified biochar