Introduction to Geotextiles
The term geotextile refers to a class of permeable fabrics that are used to separate, filter, reinforce, protect, or drain soil or soil layers. Geotextiles are usually made of synthetic polymers such as polypropylene, polyethylene, or polyester, or natural fibers such as jute and coir. Synthetic types can be produced in woven or nonwoven formats, while natural fibers are available only as woven products. The physical characteristics of a geosynthetic depend largely upon the production method. Woven geotextiles, for example, are generally less permeable to water and typically excel in filtration applications where resistance to clogging is important. Non-woven geotextiles allow much greater permeability and are commonly used for erosion control and in applications where water dispersal is critical.
Geotextiles are used in a wide range of industries. These applications range from road and bridge building to drainage and erosion control, and to landscaping applications. Synthetic, woven, landscape fabrics are manufactured in a way so that water and gasses can pass through, but light is nearly completely blocked. This combination of qualities makes landscape fabrics an effective tool in limiting the growth of weeds.
Landscape fabric is a term for a lightweight product ,suitable for residential or small-scale landscaping projects. It’s easy to work with and relatively inexpensive, but not suitable for situations where there’s likely to be a lot of foot traffic or regular disturbances. For large scale and agricultural applications, the term ground cover is more frequently used. Ground cover refers to anything that lies on top of the soil and protects it from erosion and weeds. This broader definition encompasses materials ranging from low growing annual crops like alfalfa or ryegrass to geotextiles, of both the woven and nonwoven variety.
All types of geosynthetic ground covers can be easily installed with simple tools and a bit of elbow grease. Some ground covers are available in rolls of specific widths, which can be overlapped and anchored together. In large agricultural applications, geosynthetic ground covers can be purchased in very large custom produced sheets that will cover an entire field with no need for seaming or overlapping. This is a great time and labor saver when a field is being prepared for a new planting.
Perennial food crops such as alfalfa, grapes, asparagus, and some varieties of broccoli can really benefit from this treatment, which minimizes competition for water and nutrients from invasive weeds. Perennial flowers and herbs grown for essential oils, such as lavender, peppermint, lemon balm, rosemary, and jasmine are also good candidates, especially where concerns about exposure to herbicides and other chemical treatments are a concern.
Choosing a Geotextile Ground Cloth
At first glance, it’s not always clear where the difference lies between woven and nonwoven geotextiles. They often have similar functions such as soil separation, filtration, and stabilization, for example, and depending on the specific manufacturing details, some of their performance metrics can overlap. Nonetheless, it’s important to choose a geotextile that’s suited not only to your specific goals, but to your site and soil type.
Things to consider when choosing your geotextile ground cloth include color, water permeability, UV resistance, and durability. For your site, keep in mind your soil characteristics (loamy and well drained vs heavy clay), drainage patterns, any erosion concerns, as well as local weather patterns. Even general climate information like temperature patterns can affect your choice. In hot climates, you may want to look for a white geotextile option that will reflect the sun and keep the soil cooler, while in a mild or cool climate a black cover will help the soil retain heat.
In addition to field grown crops like lavender and asparagus, many greenhouses use ground covers to protect soil on walkways and in display areas from damage due to heavy traffic, while simultaneously controlling the movement of moisture. In-ground greenhouses also use geotextiles to discourage weed growth, just like traditional field farmers. When greenhouse operators are preparing to start seeds or transplant young seedlings, the heat-retaining properties of a black geotextile cover can boost soil temperature enough that critical early starts don’t require as much supplemental energy to reach the minimum threshold.
Many proprietors of u-pick or u-cut agricultural businesses must contend with large crowds and high foot traffic within their growing areas. Mud and churned up ground in the aisles between planting rows can discourage visitors and do damage to plants, irrigation systems, etc. Woven geotextile fabrics can be lifesavers in these situations since they are able to bear heavy traffic, distribute wear and protect the underlying soil from erosion. In another possible configuration, woven geotextiles are an excellent option in situations where water needs to flow over a subsurface instead of seeping into the ground. An example, in this case, might involve installing a geotextile with low permeability characteristics and covering it with several inches of gravel. This would allow precipitation to pass through the gravel, leaving a dry surface for customers to walk and browse, while directing excess water away from the field.
When you’re considering your geotextile options, keep in mind that thicker, heavier materials will probably cost more initially, but they usually last longer, especially in situations where they’re exposed to UV effects from the sun. However, thicker material may be more difficult to tear up later. Thinner materials are more vulnerable to tears, so consider what you will be putting on top of it, and how much foot traffic it may eventually receive.
