The Utilization of Soybean Straw. I. Fiber Morphology and Chemical Characteristics

To improve basic knowledge of the properties of soybean straw, its fiber properties, anatomical structure, and components were investigated in detail. Soybean straw contains less ash and silica than some non-woody biomass. Its stem and root have more lignin and holocellulose, but less nitrogen and protein contents than the pod. Additionally, it has much shorter and wider fibers, and the length-width ratio is also lower than other crop straws. Morphologically, there are three main tissues---the ground tissue, the vascular tissue, and the dermal tissue systems in the stem, and two different morphology portions – the intimal layer and the leathery layer – in the longitudinal-section of the pod. A variety of inorganic and metal elements are distributed across the whole stem or pod in different amounts. Lastly, the planetary ball-milled stem and pod are completely dissolved in 8% lithium chloride/dimethyl sulfoxide (LiCl/DMSO) solution. After regeneration, the lignin has the highest retention, followed by silica and sugars, but most of the ash can be removed in this process.