Most accounts of the history of geotextiles report that geotextiles were invented by R.J. Barret, who began using them in erosion control projects in the 1950s, but if you look further back, geotextiles were one of the first textile type construction materials in human history. As far back as ancient Egypt, mats made of grass and linen were used for stabilization for roadways, especially when unstable soil was a problem.
Woven Geotextiles
In modern times, however, even the term woven geotextile does not refer to a single product, which explains why there can be so much variation in characteristics and even overlap with their non-woven counterparts. Woven geotextiles usually resemble plastic sheets, with the woven texture apparent only when closely examined. Traditionally, woven geotextiles have been considered inferior to nonwovens in terms of flow rate, but better materials have led to significant improvements, making some2 superior even to nonwoven products.
Slit-Film Woven
Today, there are three types of woven geotextiles: slit-film woven, monofilament, and combination woven. Polypropylene slit-film geotextiles are typically inexpensive, light, and easy to handle. They’re made by cutting slits in a sheet of polypropylene and weaving through polypropylene tape in a simple basketweave pattern. Slit-film fabrics are strong but lightweight and are primarily used in the construction of roads and embankments or where there’s a need to separate one type of soil from another. Compared to other geotextiles, slit film woven products have the lowest flow rates, as much as 35 times lower than similar nonwoven geotextiles. This extremely low permeability could cause issues during rain events in an agricultural application unless a surface drainage system, such as a lightly graded slope from centerline leading to the edges of the field into a drainage ditch is employed, along with drip irrigation to ensure the plants still receive adequate water.
Woven Monofilament
Woven monofilament geotextiles are an exception to the general rule that woven geotextiles have low permeability characteristics. In fact, woven monofilament products offer both high strength and high water flow rates. They’re especially useful in projects where high water flow in both directions is necessary, such as in flowing rivers and shorelines with tidal action. They’re produced by weaving monofilaments (think very thin fishing line) into a screen. This design leaves a fairly high percentage of open area, which not only allows free movement of water, but filters out sediment while simultaneously reducing problems with clogging. Presumably, however, the open areas, as small as they are, would inevitably allow light to pass through, making it impractical as a weed suppressant.
Combination Woven
Combination woven geotextiles are produced by weaving round monofilament yarns in one direction and flat tape yarns in the other. Predictably, they offer both strength and moderate permeability.
Woven geotextiles are valued as weed suppressors because of their ability to eliminate virtually all light. Some woven products allow both water and nutrients to pass relatively freely through to the soil, while others produced with a tighter weave allow water through only slowly.
Woven geotextiles are particularly suited for use as weed barriers around trees, shrubs, and other established plantings. Because woven geotextiles are relatively low-cost, they can also be useful in agricultural or commercial situations where the groundcover is expected to be regularly disturbed and hence will require periodic replacement.
Non-woven Geotextiles
The manufacture of non-woven geotextiles involves actively entangling differing lengths of fibers, stacking many extremely thin sheets together, and securing them by punching the layers with a barbed needle. Sometimes heat treatment is used as well to strengthen the bond. Non-woven geotextiles are usually made from polyester or polypropylene; materials that typically offer good UV protection. Despite that, it’s less durable than woven groundcovers and will usually break down faster.
When examining a non-woven geotextile, you can differentiate it from its woven cousin by carefully stretching it lengthwise. Usually, a non-woven product will stretch much more easily than a woven one.
In the past, non-woven products were considered superior in terms of permeability and breathability, but the use of newer materials used for woven geotextiles has eliminated that advantage. Nowadays, non-woven products are the preferred material to suffocate weeds and seeds beneath it. In fact, it’s a popular material to use under rock or gravel for xeriscaping since the fabric does an excellent job of preventing gravel and rocks from sinking into the soil.
Non-woven products intended for filtration and drainage will generally have a felt-like texture. They’re often referred to as “geo filter fabric.” French drains are a perfect example. In an agricultural or commercial flower and landscaping setup, a french drain using a combination of woven and non-woven geotextile may be useful to divert excess water flow during excessive rain events.
There are some nice side-benefits to using geotextiles in your garden, landscaping, or field, although they’re not typically your primary goal. One important benefit is that they help the soil retain moisture. This can be a benefit whether you’re growing thirsty plants like …. Or, specimens that like it dry. Choose the product that will produce the results you need.
Although no geotextile is 100% effective in weed control, it can make a significant improvement. Thus, you won’t need to employ toxic weed controls -- an especially important consideration in organic farms. All in all, remember that when you’re facing a handful of weeds vs a field full of weeds, landscaping fabric can make all the difference.
