This post is part of the Science Tuesday feature series on the USDA blog. Check back each week as we showcase stories and news from USDA’s rich science and research portfolio.
In the depths of winter, planting grass seed isn’t at the top of one’s to-do list. But soon, spring will arrive and landscaping companies will be out, spraying that green mixture of seed and mulch on patches of bare ground.
Hydromulch, a temporary, porous layer that can help protect newly sown seeds, contains water, dye, a mulching material, and a binder, which keeps the mulch intact. Typically the binder is made from guar gum, made by grinding beans of the guar plant into powder. When water is added, the powder forms a viscous gum.
Now, USDA Agricultural Research Service (ARS) scientist Steven F. Vaughn and his colleagues have found that a half dozen plant-derived compounds outperformed guar gum in laboratory studies. These alternative binders may prove to be less expensive than guar gum.
The list of top-performing binders, documented in a 2013 scientific article in Industrial Crops and Products, includes xanthan gum, made by the bacterium Xanthomonas campestris, and gums extracted from seeds of two members of the mustard family, camelina and lesquerella.
Also making the list: a starch-based material, known as a high-amylose starch-lipid complex, that's made of cornstarch loosely bound to sodium palmitate, a fatty acid found in many everyday vegetable oils.
The panel of 10 compounds selected for the lab tests appears to be unique. Although starch has been used commercially as a hydromulch binder, the high-amylose starch-lipid complexes, made with an eco-friendly method developed by Vaughn's ARS colleagues, apparently had not been previously lab-tested for this potential use.
Vaughn is now coordinating a series of outdoor tests as a follow-up to the indoor experiments.