Can You Reuse Coco Coir When Growing in the Soilless Medium?

Coco coir is a popular growing medium used in soilless cultivation due to its excellent aeration, water retention, and nutrient-holding properties.

However, the question that arises among growers is whether coco coir can be reused in subsequent crop cycles. Reusing coco coir can have economic benefits, although it requires proper preparation and understanding of the medium’s characteristics.

What is coco coir?

Coco coir, also known as coconut coir, is derived from the fibrous husk of coconuts. It is processed into various forms, including coco pith (peat), coco fibers, and coco chips. Each form has its advantages and uses in horticulture.

• Coco peat has excellent water retention capabilities, making it an excellent selection for plants that require consistent moisture.

• Coco fibers provide good aeration and allow for oxygen penetration into the root system.

• Coco chips combine the properties of peat and fibers offering both water retention and aeration.

Coco coir works well as a soil amendment or as a standalone growing medium in hydroponic systems. It is pH-neutral and environmentally friendly, as it utilizes coconut husks that would otherwise go to waste.

However, it does have some inherent drawbacks, such as its potential high salt content and ability to lock out nutrients like iron, magnesium, and calcium.

What are the pros and cons of reusing coco coir?

Pros

• It helps reduce operational costs by avoiding the need to purchase new growing media for each cycle.

• Used coco coir contains residual nutrients and organic matter from previous plants, which can benefit new crops.

When coco coir is reused, it undergoes degradation and becomes finer, improving its water retention properties over time. The presence of decomposing root structures from previous crops reduces channeling in the medium and improves water distribution.

Cons

• After a crop cycle, the chemical composition of the medium changes, making it more variable. This requires growers to adjust their nutrient management strategies to ensure consistent results.

• If the coco coir is reused without proper adjustments, nutrient imbalances and overaccumulation can occur, affecting plant health and productivity in hydroponic systems.

Preparing Coco Coir for Reuse

To reuse coco coir effectively, growers need to follow these steps;

• Flushing the coco coir

• Preparing it for decomposition

• Adjusting nutrient levels

Flushing involves irrigating the medium with plain water to remove excess nutrients and salts. This helps prevent nutrient imbalances and ensures a clean starting point for the next cycle.

Before the crop cycle ends, beneficial additives such as enzymes and microbes should be introduced to help break down the remaining organic matter and prevent pathogen growth. Pondzyme and probiotics are some of the commonly used additives to facilitate decomposition and create a favorable microbial environment.

Once the crop cycle is complete, the main root ball should be removed from the coco coir. While it is not necessary to remove all plant material, large roots should be discarded. The coco coir should then be allowed to dry, making it easier to break up the remaining root structures.

Flushing and Buffering Coco Coir

After the coco coir has been dried up and broken, the next step is to flush and buffer the medium before reuse. Flushing involves rinsing the coco coir with water or a low EC nutrient solution to remove any remaining salts and nutrient residues. This step helps restore the coco coir’s pH and EC levels to an optimum range for plant growth.

Buffering helps ensure the medium’s cation exchange sites are replenished with calcium. This process involves soaking the rinsed coco coir in a solution containing a high dose of Cal/Mag supplement. Doing this ensures that the coco coir has enough calcium for the next crop cycle.

Evaluating Nutrient Requirements

When reusing coco coir, assess the nutrient requirements for the new crop. Analyze the runoff EC to determine the type of nutrition needed. If the runoff EC remains above 1.5 mS/cm, a solution containing potassium nitrate and micronutrients should be fed to the new plants. Once the runoff EC drops, the normal nutrient regime can be resumed.

Please note that coco coir possesses a good degree of nutrient buffering capacity due to its high cation exchange capacity. With the right approach, you can maximize the benefits of Coco Coir as a sustainable and efficient growing medium.