Rethinking Cardboard in No-Till Gardens: A Closer Look at Soil Preservation

To cardboard or not to cardboard?

No-till gardening has gained widespread popularity in recent years, with cardboard being a commonly used tool to smother existing vegetation. However, the question arises: is cardboard truly the best option for achieving the goals of no-till gardening, particularly the preservation of soil life? In this exploration, we delve into the potential drawbacks of using cardboard and propose an alternative approach that not only effectively suppresses weeds but also nurtures a thriving soil ecosystem.

The Downside of Cardboard:

While cardboard proves effective in killing unwanted vegetation, its suffocating nature poses a significant threat to soil life, particularly aerobic organisms. Studies have revealed that cardboard is highly oxygen impermeable, and when buried beneath 6-8 inches of soil, it hampers the exchange of gases essential for the well-being of soil microorganisms. This contradicts the core principle of no-till gardening, which aims to promote a healthy and vibrant soil ecosystem.

Disturbance to Soil Structure:

Another aspect of the cardboard method that raises concerns is the disturbance caused to the soil structure during the process of piling soil on top of it. Whether the soil is sourced from bags or the existing garden, the disturbance can negatively impact the delicate balance of microorganisms in the soil. The very method intended to preserve soil life may inadvertently contribute to its disruption.

Contaminant Concerns:

Further compounding the issue are concerns about contaminants present in cardboard. Research comparing recycled cardboard as animal bedding in chickens has highlighted elevated levels of PFAS (forever chemicals associated with endocrine cancers and other health problems). These contaminants could potentially find their way into the soil, compromising its health and fertility.

An Alternative Approach:

In light of these concerns, an alternative method emerges as a more soil-friendly approach to no-till gardening. Instead of relying on cardboard, consider scalping down existing vegetation as close to the surface as possible and applying a layer of 8-11 inches of wood chips sourced from an arborist.

Benefits of Wood Chips:

1. Moisture and Oxygen Permeability: Unlike cardboard, wood chips allow moisture and oxygen to reach the soil surface. This promotes aeration and maintains a conducive environment for soil life.
2. Weed Suppression Through Light Deprivation: The layer of wood chips effectively blocks sunlight, suppressing the growth of existing vegetation without the detrimental effects associated with cardboard.
3. Slow Conversion to Rich Soil: While this method may take some time, it results in the gradual transformation of grassy areas into landscaped or garden beds with nutrient-rich soil. The process aligns with the essence of no-till gardening by fostering a healthy and thriving soil ecosystem.

Conclusion:

While cardboard has been a go-to solution for no-till gardeners, its drawbacks in stifling soil life and potential contaminant issues prompt a reevaluation of its use. The alternative approach of using wood chips not only addresses these concerns but also contributes to the long-term health and fertility of the soil. As we strive for sustainable and ecologically sound gardening practices, it’s essential to choose methods that align with the overarching goal of preserving and nurturing the intricate web of life beneath the surface.