Beware of Weed Fabric

Weed Fabric Is a Barrier to Soil Fertility

Many gardeners understand the importance of building healthy soil for their gardens and landscapes and employ practices such as incorporating soil amendments (compost & manure) to improve soil structure and fertility that support many functions of plant health.

Using a weed fabric in the garden and landscape with a topical surface treatment such as a bark mulch or other natural materials, does not prevent weeds from volunteering and taking hold in the garden. Covering the soil with fabric in an attempt to rid the site of unwanted weeds is the beginning of the end for biologically active soil because it creates a lifeless rhizophere that could exist at the plant root interface.

When a weed fabric is in place, decomposing leaves, plant matter, bark mulch and other plant detritus that would normally be available to the soil remains on top of the weed fabric unable to filter down. This prevents absorption into the soil thus inhibiting important soil aeration. Fabrics also contribute to ground compaction which forces tree roots to rise to the surface making them less resilient to drought and less able to uptake available nutrients.

Fabrics inhibit the underground soil network from thriving. This underground network is comprised of a multitude of cooperating organisms (such as fungi, bacteria and protozoa) which play a major role in soil health and plant vitality.

Back in 1904, Lorenz Hiltner, a scientist and pioneer in rhizosphere microbial ecology and soil bacteriology coined the term rhizosphere that centered on the idea that plant nutrition is considerably influenced by the microbial composition and is critical for plant-microbe interactions and as a consequence, nutrient cycling, plant growth and disease resistance in plants.

He became convinced that root exudates of plants support the development of different bacterial communities and that plant nutrition is considerably influenced by the microbial composition of the rhizosphere. (agris.fao.org)

Weed fabrics are a barrier to biologically productive soils and are antithetical to producing vibrant living systems. There are several viable alternatives to weed fabrics that are biodegradable, permeable and which will enhance soil productivity:

• Cardboard (single or double layered)
• Thick layers of newspaper
• Leaves
• Woody or herbaceous ground covers
•  3” layer of sifted bark mulch

Instead of using weed fabric in the garden, use it beneath gravel or crusher fine paths. The fabric keeps the gravel from migrating into the soil and helps keep the path intact.

Useful Definitions

Rhizophere: A region of soil surrounding roots critical for plant-microbe interactions and, as a consequence, nutrient cycling, plant growth and disease resistance in plants. (www.rhizosphere.org)

Root exudate: Produced by the roots and are made up of many components that can respond to the plants needs with organic acids, amino acids and carbohydrates being the dominant ones. In addition to helping plants procure nutrients, exudates are food sources for the microbes that are an important part of the soil microbiome. (soils.org) Paul Hallett, Soil Science Society of America.

Biomimicry: A practice that learns from and mimics the strategies found in nature to solve human design challenges. For all the challenges we face, nature has a solution. Biomimicry offers an empathetic, interconnected understanding of how life works and ultimately where we fit in. (biomimicry.org)

Ecological Resilience: The capacity of an ecosystem to respond to a disturbance by resisting damage and recovering quickly. (terraflora.us)