Landscape, Nursery, Turf, and Greenhouse - Water Absorbing Polymers

I recently had a converstion with an owner of a lawn maintenance company. He mentioned that another company was having success with water absorbing polymers injected into turf. I thought I would do a series on water absorbing polymers and their use in horticulture. The first post is general information on what these polymers are and their use.

Water absorbing hydrogel polymers have the potential to have a large number of benefits on the landscape. They have proven to be an aid in decreasing erosion, thus reducing nutrient and sediment losses to sensitive environments, and adsorb nutrients for slow release. Hydrogels have also, in most circumstances, aided in the establishment of plants, mycorrhizae, and bacteria. However, the most important aspect concerning hydrogels is that responses associated with them are site-specific variables (i.e. soil structure, salt and fertilizer concentration) and often species-specific variables (i.e. what conditions the plant normally grows). Given the adverse side effects potentially associated with the hydrophilic polymers, care should be taken in determining what the ultimate objectives of the project are (i.e. temporary plant establishment or permanent, irrigated or unirrigated, etc.). Therefore each field use must be carefully analyzed for organism responses expected due to the wide range of results possible when using these products.

Hydrogel polymers used in horticulture are usually formulations commonly made of starch-polyacrylonitrile graft co-polymers (starch co-polymers: SCP), vinyl alcohol-acrylic acid co-polymers (polyvinylalcohols: PVA), and acrylamide sodium acrylate co-polymers (cross-linked polyacrylamides: PAM). All of these hydrogels when used correctly and in ideal situations will have at least 95% of their stored water available for plant absorption. Natural polymers (i.e. starch based SCP) are very fast hydrators and will usually completely hydrate in as little as two hours where as the synthetic polymers (i.e. PVA or PAM) can take six hours or more to fully hydrate. Usually synthetic polymers like PAM are used over natural polymers since they tend do last longer in the soil matrix because they are less biodegradable.

Information reprinted from "Hydrophilic Polymers – Effects and Uses in the Landscape" by Daniel Peterson in the Restoration and Reclamation Review Student On-Line Journal, University of Minnesota, St. Paul, Minnesota (USA), Department of Horticultural Science
URL: http://hort.agri.umn.edu/h5015/rrr.htm