Interaction effects of biochar levels, irrigation regimes, and irrigation water salinity levels on wheat II: grain and soil ions concentration and soil water retention curve

In recent decades, the application of biochar to improve soil fertility and soil physical property and also enhance crop tolerance to abiotic stress has been proposed by researchers. Therefore, the effect of three levels of biochar (zero, 40, and 80 Mg ha^-1) produced from wheat straw, irrigation water salinity (0.6, 6, and 12 dS m^-1), and three irrigation regimes (50, 75, and 100% of crop water requirement) on wheat grain ions and soil ions concentration as well as some soil physical properties after wheat harvest were investigated under greenhouse conditions. The results showed that the Na+ and K+ concentration in soil significantly increased by application of biochar and also salinity, while application of 50% deficit irrigation significantly declined the Na+ and K+ concentration in soil. Also, the soil ECe of the highest level of biochar and salinity increased 2.1 and 1.59 times that of without biochar and salinity, respectively, while application of deficit irrigation significantly declined the soil ECe due to lower application of saline water and lower accumulation of salt. Considering the main effects of treatments, application of the highest level of biochar (80 Mg ha^-1) increased the K+ concentration in grain, while application of saline water (6 and 12 dS m^-1) and deficit irrigation (75% and 50 %) both declined the K+ concentration in grain. The application of biochar enhanced the soil water holding capacity. In conclusion, it is recommended to apply wheat straw biochar to increase soil fertility and increased water storage capacity in the soil. Finally, the application of non-saline biochar is suggested to prevent salinization and the destruction of agricultural soil.