Effects of wheat straw biochar and irrigation water on hydraulic and chemical properties of a sandy loam soil after faba bean cultivation

Nowadays, applying soil amendments is one of the most important ways to cope with water shortages and improve soil physical properties. In this regard, a greenhouse experiment was conducted to study the effect of different levels of irrigation water and wheat straw biochar on physical and chemical properties of a sandy loam soil, after harvesting faba bean. The experiment was performed with ۵ biochar levels (۰, ۸, ۱۶, ۲۴ and ۳۲ g kg-۱) and ۳ irrigation levels (۱۰۰%, ۷۵% and ۵۰% of crop water requirement) using completely randomized design in three replications. Lowering the irrigation level to ۵۰% did not influence soil physical and chemical properties except for saturated hydraulic conductivity (Ks), as Ks was significantly declined under ۵۰% irrigation water levels as compared with full irrigation. Soil bulk density and particle density of ۳۲ g kg-۱ biochar treatment (B۳۲) was reduced by ۴۷% and ۲۷%, respectively, while soil porosity and Ks increased as compared to no biochar application (B۰). Under B۳۲ treatment, the saturated electrical conductivity increased ۵.۶ times, and the cation exchange capacity and sodium adsorption ratio (SAR) was increased by ۴۰.۳% and ۵۳.۶% in comparison with B۰, respectively. This made the soil saline (ECe>۴ dS/m) but not sodic (SAR-۱)۱/۲). It can be concluded that although, biochar level of ۲۴ g kg-۱ did not considerably increase soil water holding capacity compared to B۰, it significantly improved the other soil physical and chemical properties, therefore, it can be used as soil amendment.

Keywords:

Cation exchange capacity , Saturated hydraulic conductivity , Sodium adsorption ratio , water holding capacity