Technical Data

Performances of Coco Peat as growing media

Evaluation of Coco Peat as a Plant Growth Medium

A few well-designed studies have assessed the performance of Coco Peat as a plant growth medium.

Cresswell (1992) compared Coco Peat with both sphagnum and sedge peat as a growing medium for broccoli, tomato, and lettuce seedlings. He found that Coco Peat resulted in earlier germination and greater seedling size and uniformity compared to the other media.

Handreck (1993) tested the growth of Petunia x hybrida 'Celebrity Salmon' in 5.6:1 (v:v) mixes of either Malaysian coir dust, Sri Lankan Coco Peat, or sphagnum peat from Sakhalin, Russia, combined with silica sand. He observed equal growth in all three mixes when pH was adjusted to 6 and total plant nutrients were supplied, but noted varying performance with different nutrient regimes. He concluded that plants in Coco Peat-based media require more calcium (Ca), sulfur (S), copper (Cu), and iron (Fe), but less potassium (K) than those grown in peat. Additionally, he observed greater immobilization of soluble nitrogen in Coco Peat compared to peat moss, a finding also confirmed by Cresswell (1992).

Trials at Whittle College in England with various woody ornamentals in different Coco Peat blends showed comparable performance to sphagnum peat. Unpublished technical reports from other institutions in England have indicated similar results with a wide range of greenhouse crops.

An experiment conducted at the University of Florida Fort Lauderdale Research Center (Meerow, 1994, 1995) tested the efficacy of Coco Peat as a peat substitute in replicated trials. Ixora, Anthurium, majesty palm, and Pentas were grown in container media that differed only in the peat fraction (40%). One mix used sphagnum, another used Florida (sedge) peat, and the third used Coco Peat. The Pentas, Ixora, and majesty palm grew significantly better in the Coco Peat mix compared to the sedge peat mix. Interestingly, Anthurium grew almost as well in the sedge peat mix as in the Coco Peat mix. The Pentas, majesty palm, and Anthurium showed equal growth in the Coco Peat and sphagnum media. Only the Anthurium exhibited slightly better top growth in the sphagnum mix. The sedge peat-based medium had the greatest air space and the lowest water-holding capacity at the start of the trials, but these parameters reversed by the end of the experiment. The Coco Peat-based medium showed the least change over time. The higher initial air porosity of the sedge-based medium may have supported better initial root growth for Anthurium, as it is epiphytic in nature. No evidence of chloride (Cl) or sodium (Na) toxicity was observed in plants grown in the Coco Peat-based medium, and conductivity measurements indicated low levels of total dissolved salts. Informally, it was also noted that seeds sown in a 1:1 (v:v) mix of Coco Peat and perlite developed larger root systems than those germinated in a 1:1 mix of sphagnum and perlite.

Research in Sri Lanka

An experiment by L.H.J. van Holm & M. Fernando evaluated the response of Albizia falcataria to dual inoculation with vesicular-arbuscular mycorrhiza (VAM) and a Rhizobium strain. The potting medium consisted of compost, coir dust, and soil. Previous studies had shown that compost inhibits the spread of mycorrhizal infection. This study determined that coir dust showed no reduction in colonization compared to soil, indicating no biological or physicochemical inhibition. Coir dust produced greater colonization at all harvests, except the fourth, where colonization was reduced in the autoclaved compost medium. Therefore, coir dust was found to be suitable for VAM fungal culture due to its lack of biological inhibition and favorable physicochemical properties.

Soil Organic Matter and Nitrogen Mineralization

A study by Dr. K.A. Nandasena & Mr. L.H.J. van Holm investigated the active fraction of soil organic matter and potential nitrogen mineralization. Rice straw, coir dust, farmyard manure, and Gliricidia sepium leaves were monitored in three soils with different organic matter contents. Organic matter addition increased CO2 production in all materials except Coco Peat. The effect was enhanced with higher doses of incorporation. Fresh rice straw and Gliricidia sepium had a higher effect than farmyard manure and Coco Peat. Higher microbial populations were observed when Coco Peat was added, with a slight increase in numbers as the dose increased. Fiber-rich Coco Peat mainly enhanced the humic fraction, which is highly beneficial for soil health.

Challenges of Using Coco Peat

Research from Sri Lanka has reported that Coco Peat can contain chlorides at levels toxic to many plants, making it crucial to monitor the salinity of the raw material before processing it into horticultural amendments. Chemical properties can vary significantly by source (Evans et al., 1996). The higher pH of coir dust may reduce the need for lime in a Coco Peat-based medium, although dolomite is more important for calcium (Ca) and magnesium (Mg) nutrition than for pH elevation. Cresswell observed a minor nitrogen drawdown with Coco Peat, but typical fertilization practices would likely compensate for this small loss. However, it is still unclear whether further adjustments in fertilization are necessary in media primarily composed of Coco Peat.

Coco Peat does not naturally contain sufficient plant nutrients, so farmers may need to add fertilizer to prevent nitrogen (N) deficiency during decomposition (M. Arenas & C.S. Vavrina, 2002).

Pre-treatment and Challenges with Coco Peat

Further research has shown that Coco Peat requires pre-treatment before use as a growing medium. Early attempts failed due to the high potassium (K) and sodium (Na) content naturally found in coir dust. When growers added calcium or magnesium, the potassium and sodium were released, damaging the plants (www.hydroponics.co.uk/organic_growing_media).

Remedial Actions to Overcome Coco Peat Issues

1. Washing: Polyphenolic compounds in Coco Peat are water-soluble, and washing with water can help remove these compounds.

2. Recycling Soaking Water: Recycling soaking water is an economical way to reduce toxicants in fresh coir dust. Coir mills should have the capacity to recycle water or replace a portion with fresh water to maintain water volume.

3. Adding Synthetic Compounds: Adding calcium nitrate (CaNO3) to fresh coir dust enhances calcium levels and facilitates cation exchange, helping to remove salts like sodium (Na) and iron (Fe).

4. Composting: Composting Coco Peat increases its nutrient content and reduces polyphenolic compounds through oxidation. This value-added Coco Peat is highly sought after in the market as it closely resembles mined peat.

Comparison of Coir Dust and Peat

PeatCoir Dust

Originates from the partial decomposition of plant material under low oxygen, poorly drained conditions.Produced as a by-product when coconut husks are processed for fiber extraction.

Natural processMechanical process

Typically black in colorBrown when fresh, becomes black upon decomposition

Very low pH (4.0 – 6.5)pH around 6.0 – 7.0

Very low EC values (0.2 – 1.0)Fresh EC can vary from 0.2 – 2.3

Value-Added Coir Dust

Coco Peat contains a high amount of lignin, making it take decades to decompose. Studies by various institutions have developed methods to speed up the decomposition process by reducing lignin using fungal or microbial cultures.

While Coco Peat does not contain sufficient nutrients, farmers must add fertilizer to their crops. Otherwise, the decomposition process may begin, leading to temporary nitrogen deficiency (M. Arenas & C.S. Vavrina, 2002).

Early attempts at using Coco Peat as a growing medium faced challenges due to its high potassium and sodium content. When calcium or magnesium was added, these salts were released, causing plant damage (www.hydroponics.co.uk/organic_growing_media).

Thus, effective value-adding processes should be developed to mitigate the above issues with Coco Peat.