OldBasilisk

Coco Coir (Fr: Advanced Nutrients https://www.advancednutrients.com/ad...ID=462&catID=6)

Coir has become the standard medium of choice for many hydroponic growers. Cubes and bales of highly refined and uncontaminated coir are marketed around the world for greenhouse growing. Growers use coir for incorporation into soil mixes and grow hydroponically in 100% pure coir.

When sourced from horticultural suppliers, coir is a substrate that has reliable properties of water holding capacity, drainage and cationic exchange. Compared to peat moss, coir has a more ideal pH range, well above the acidic ph of Peat moss. Coir is unique in exhibiting very little shrinkage or settling of the medium as it ages; because of it’s complex cellulose and lignin make up, it does not decompose or ‘collapse’ with age and exposure to oxygen.

Coir is an abundantly available and easily processed natural by-product of the coconut farming industry. Coir is essentially the coarse, granular “dust” that is generated when the large, spongy husk of a coconut is ground up to remove the stringy fibres. The fibres are used in making mats, rope and as stuffing, while the dust can be adapted for use in hydroponic growing.

Horticultural supply companies that process the raw coir to remove contaminants and to ensure a standard quality is available for modern growers. However there are traits about the processed coir substrate that growers still need to be aware of in order to maximize growth and yield.

These properties concern the cationic exchange capacity (CEC) of coir; it is quite high. Coir is principally cellulose, which are long chains of sugar molecules usually called “structural carbohydrates” in the make up of the coco husk. Carbohydrates have a typical ratio of oxygen that approximates CH2O, so cellulose is covered with electronegative points where-ever oxygen occurs.

Cations are simply positively charged atoms and minerals dissolved in solution; K+,Ca2+, Mg2+, Fe2+, Mn2+, Cu2+, Mn2+, Zn2+,Co2+ are all examples of cationic plant nutrients. Cationic exchange by coir is the process by which the positively charged atoms become drawn and attached by “ionic bonding” to the numerous negatively charged oxygen atoms that are in the cellulose stands of coir.

When coir ages during the duration of a crop cycle, the cationic adsorptive capacity of coir increases, and growers using coir have leaned that CEC will “lock up” some elements in aged coir.

At higher pH levels coir will bind more cations, and “charge up” on these, and this can push the nutrient balance in the solution out of the ideal range for certain nutrients or plant preferences. Potassium is the most likely element to be adsorbed element this way; and then be released in higher amounts when pH drops. Coir is also naturally high in potassium, pre-adsorbed to the cellulose fibres. The solubility of the secondary elements magnesium (Mg2+) and calcium (Ca2+) is also affected this way by coir.

A high cationic exchange capacity (CEC) is one of the unique properties of coir. The cellulose of coir can draw these cations out of solution, trapping them in the coir until there are appropriate pH changes, or by other influences such as root absorption of the elements.

Although horticultural grade coir is usually processed to a uniform quality, these coir-specific nutritional requirements will be present in all coir based growing systems.

Comparing Coir to other Growing Media:

At the University of Arizona plant scientists have compared growing crops in coir to other media. Although there are always species specific considerations, these researches used tomato as their test plant. In an article called “Comparing Five Growing Media Physical Characteristics and Tomato Yield Potential”, the researchers describe their work:

“The greenhouse tomato cultivar, Trust, was seeded August 3, 1996, to rockwool cubes. The seedlings were transferred to rockwool blocks on August 17 and placed on the growing slabs, August 31. The research greenhouse was located at the University of Arizona, Campus Agricultural Center in Tucson, Arizona.

The research consisted of the six following treatments:

1. Rockwool - 3 plants/slab
2. Peat-lite - 3 plants/bag
3. Coconut Coir - 3 plants/bag
4. Coconut Coir/Perlite - 3 plants/bag
5. Perlite - 3 plants/bag
6. Perlite - 6 plants/bag


The volume of medium in each bag was approximately 30 liters. The rockwool slabs measured 7.5 cm x 15.0 cm x 90 cm or a volume of slightly more than 10 liters. Each treatment had 18 plants and was replicated twice. With each irrigation, water soluble fertilizer was injected into the water. On bright sunny days, mature plants would be fertigated over 30 times per day.

The first flowers appeared September 11 and were bee pollinated. The first harvest was November 16, 1996.

The crop was harvested approximately every two days. The marketable and total yield was recorded along with fruit size of the marketable product. The tomato crop was terminated March 29, 1997.”

The most interesting data missing from here are the specifications of the fertigation solution these researches used. This was a significant input both to the plants themselves and we should note, in a physical sense, to the media. The media was soaked up to 30 times a day, and went through variable wet-dry cycles for 7 consecutive months !

The results from this experiment with tomato and coir were described as such:

“The plant growth response to all the different media appeared the same. The irrigation requirements were similar as were the fertilizer needs. The perlite bags containing six plants needed to be irrigated considerably more than those bags having three plants.

For a four-month harvest period (November 16 - March 29) the yield was quite good for winter production. The fruit size was largest during the first two months of harvest. The marketable tomato yield is reported as :

Media Yield / plant (kg/m^2) Size of fruit(g)
Coir 26.58 196
Perlite (3 plt./bag) 25.69 195
Peat-lite 24.81 193
Coir/Perlite 24.27 192
Rockwool 24.02 185
Perlite (6 plt./bag) 23.40 192


These scientists neglected to report the specifics of their fertigation solution, however we can see from these yield data that this winter crop grew abundantly over seven months. We can only conclude that their input of soluble fertilizers was strong enough to avoid having any of the cationic binding associated with coir impact on plant growth.

The scientists at the University of Arizona continue to summarize the results of their experiments with coir:

“While there appeared to be a difference in marketable yield and fruit size between growing media, the differences were not statistically different.

There was a great difference in the physical properties of the growing media . The water holding capacity and air porosity is vastly different. There is speculation that the combination of high water holding capacity and low air porosity can be detrimental during periods of high air temperature, which can influence higher nutrient temperature in the bags, therefore possibly lower oxygen content in the solution.

Perlite is opposite of rockwool in that it has low water holding capacity but high air porosity. In order to maintain a large fruit size and high yield, growers using rockwool intercrop a second tomato crop. Growers using perlite have no need to intercrop. Fruit number and size does not seem to be affected by producing from the same plant the entire growing season when growing in perlite. It is thought that high temperature solution during the spring months will be more of a problem in rockwool versus perlite.

Since this is speculation, this hypothesis needs to be tested. To intercrop with a second crop is costly. Growers not having to intercrop certainly have an economic edge since the process of intercropping by planting a new crop in with an existing crop, which is later removed, is time consuming and expensive.

In the United States, most growers will discard the rockwool in a landfill after one year’s use. Normally, perlite is also not reused, but taken away by growers of ornamentals or it can be sterilized, rebagged and used again for greenhouse vegetable production. The peat in the peat-lite mix was quite decomposed while the coconut coir did not decompose as readily as peat. It appears that the coir could be reused. Whether it should be sterilized before reuse, needs to be investigated.”

Because of it’s much lower cost, virtually ideal physical characteristics for growing and by being recyclable in subsequent gardens, coir becomes a very attractive alternative to rock wool and perlite. Since this experiment with rich fertigation using tomatoes showed no difference in yields, this experiment highlights the practicality of coir.

In conclusion these scientists at the University of Arizona state:

“There were no significant differences in yield and fruit size among the five different growing media. There is a real difference between the physical properties, of rockwool and perlite. Coconut coir and peat-lite had a similar water holding capacity to rockwool but had twice the air porosity. In the southwestern part of the United States and northern Mexico, rockwool and peat-lite are far more expensive than perlite and coconut coir. Perlite is undoubtedly suitable for greenhouse vegetable production. Coconut coir also appears suitable.”

How Coir is Made:

Coir is produced in abundance by tropical countries were coconut tree plantations are managed. Coir is the “pith” of the large husk that surrounds each coconut ripening on trees. Coir in the form of a granular dust ends up being a final product when the husk is processed for its valued fibre.

The potential use of the pith of the coconut husk in agronomy was recognized in 1949, when it was referred to as “cocopeat”. In an article written by Alan. W. Meerow at the University of Fort Lauderdale in Florida entitled “Coir Dust, a viable alternative to Peat Moss” describes the recent history of Coir’s use in various industries including horticulture:

“In 1949, E. P. Hume wrote an article in the journal Economic Botany extolling the horticultural virtues of a by-product of the coconut husk fibre processing industry. Coir is the name given to the fibrous material that constitutes the thick mesocarp (middle layer) of the coconut fruit (Cocos nucifera). The long fibers of coir are extracted from the coconut husk and utilized in the manufacture of brushes, automobile seat and mattress stuffing, drainage pipe filters, twine and other products. Traditionally, the short fibers (2mm or less) and dust ("pith") left behind have accumulated as a waste product for which no industrial use had been discovered. Hume write of the excellent growth obtained with various plants when this coir dust or, as he called it, "cocopeat," was used as the growing medium (this word has now been registered as a trademark by one manufacturer of the material).”

From those early days when E.P. Hume experimented with “cocopeat”, efforts have been continually improving coir as a product for agronomic practices. Modern greenhouse operators have adapted their fertigation regimens to meet the unique traits of coir, and some growers recognize how certain plant species thrive in this medium better than in all others.

Many modern growers develop their own coir-specific recipes, and learn to compensate for coir’s pH-dependant CEC by trial and error. Author Alan Meerow continues to describe the coir industry:

“Hume was a prophet before his time. It is only in the last 10 years that his words of wisdom have percolated through the often conservative ways of international horticulture. In the 1970's and 80's, initial tests in Australia and Europe indicated that coir dust could function remarkably well as a substitute for various peat products in Soilless container media for plant growth. Several Dutch companies have in fact been using coconut coir dust in production media since the 1980's, and the Royal Botanic Gardens at Kew is currently shifting most of its plant production into coir dust-based media. Sri Lanka (where over 2.5 billion coconut fruits are processed each year) has become the leading processor of what had previously been considered a waste product into a form suitable for horticultural use.”

Modern growers are now using coir all over the world. Although it is sourced in tropical climates, modern processing methods and transportation systems allow this resource to be used in all settings. During the start up of the modern industry of coir processing some quality issues had to be solved, as Alan Meerow explains:

“While other sources may be available, companies in Sri Lanka have invested heavily in an infrastructure that guarantees consistency and quality of the product. Problems that can occur with coir dust where attention to quality control is not a priority include contamination with animal manures (with the attendant possibility of salmonella) and excess salinity. The former can be a problem in India, where cows often range free. The latter can occur anywhere where "green" coconuts are harvested for coir extraction. Unripe nuts are usually soaked in brine to make the fibers easier to extract, while fresh water is used with fully ripe coconuts.”

Contamination was a large pitfall of early coir use in horticulture. Not only were free ranging animals and salt contamination frequent issues to deal with, but some sources became contaminated with herbicides. This happened when large piles of old coconut husks piled up for years and fostered weed growth. To manage these weedy, old husk piles, coconut farmers were tempted to apply herbicides to knock down the weeds before sending the waste pile off for coir manufacture. In some cases these pesticides ended up in the coir used in agronomy. Alan Meerow continues:

“Coir dust accumulates in large piles or dumps outside of the mills which process the husks for extraction of the industrially valuable long fibers. The high lignin and cellulose content of the pith prevents the piles from breaking down further. Some of the piles in Sri Lanka are reportedly a century old! It is this same characteristic that prevents oxidation and resultant shrinkage of coir dust when it is used as a growing medium.”

Now that modern growing systems that are based around coir have huge demands for quality assurance, industrial production methods have worked risks and variabilities out of coir production. Scientists have even studied how coir and fertilizers interact to hold and release nutrients, profiling the chemistry of coir in detail.

For example, in an article called “Determination of Available Macronutrients, Na, Cl, pH and EC in Coir Substrate Incubated with Mineral Fertilizers” found in the publication Acta Horticulturae vol.697 (2005) scientists in Brazil examined how coir held onto nutrients after “incubating” samples with various sources of fertilizers for 20 to 120 days.

They wanted to see if coir changed the nutrient solution by locking up nutrients or through causing pH changes. At the same time attempting to evaluate a nutrient mix that would be better suited to coir, they report:

“Coconut fibers has been considered an adequate alternative material as substrate for Soilless potted plants under semi or protected cultivation. Several water extracts are used for the determination of pH, EC and available nutrients in substrates for plants, but there is little information about the relations among them for a more correct plant nutrient evaluation. The objective of this research was to compare current procedures of water extraction for the chemical analysis of coir substrate incubated with conventional NPK and slow-release fertilizers (SRF).

They describe their methods and result more:

“Samples were collected at 20, 60 and 120 days of incubation and submitted to the following water extraction methods: 1:1.5 v/v; 1:2 v/v; 1:5 v/v; 1:10 m/v; and saturation extract. NPK showed a faster nutrient-releasing rate compared to the SRF. The substrate did not present excess sodium or high electrical conductivity (EC). However, pH decreased with period of incubation independently of treatment. The initial pH was increased in the conventional NPK-fertilizer and decreased in the SRF treatments. Ammonium and nitrate presented a different behaviour along the time, according to fertilizer source. Phosphorus concentrations were not influenced, however, EC and all other macronutrients in the coir substrate were significantly affected by the water extraction methods. The best methods for the substrate analysis were the saturation and 1:1.5 water extracts for nutrient evaluation purposes.”

So again these scientists are studying the differing behaviours of plant nutrients when mixed with coir. They mixed different formulations of fertilizer in coir and allowed it to “incubate”, observing pH will drop and that nitrogen will be locked up if in ammoniacal form. They also recognized the appropriateness of only certain methods to measure these things accurately.

OldBasilisk

The Composition of Coir:

At the physical level coir appears similar to peat moss, but there are clear chemical differences. Our expert author on coir and peat moss explains:

“Coir dust is very similar to peat in appearance. It is light to dark brown in color and consists primarily of particles in the size range 0.2-2.0 mm (75-90%). Unlike sphagnum peat, there are no sticks or other extraneous matter. Independent analyses of coir dust were performed in May and June 1991 at Auburn University, University of Arkansas, and A&L Analytical Laboratories (Memphis, TN).

The higher pH of coir dust (compared to peat moss) may allow less lime to be added to a coir dust-based medium, though adding dolomite to container soils is more important for Ca and Mg nutrition than for elevating pH. Cresswell did find that a small amount of nitrogen drawdown (N kept from availability to plants during decomposition of organic amendments low in nitrogen) occurred with coir dust, but typical production fertilization practices would likely compensate for the small amount of resulting N loss. G. C. Cresswell (1992) looked at coir dust in comparison to sedge and sphagnum peat products and concluded that it has superior structural stability, water absorption ability and drainage, and cation exchange capacity compared to either sphagnum peat or sedge peat.

Coir dust tends to be high in both sodium and potassium Handreck, 1993) compared to the other peats, but Na is leached readily from the material under irrigation (Handreck, 1993). The high levels of potassium present in coir dust are interesting to note, and may actually prove more a benefit than any detriment to plant growth. Coir dust from sources other than Sri Lanka have also reportedly contained chlorides at levels toxic to many plants, thus it is very important that salinity in the raw material be monitored before processing into a horticultural amendment. It is evident, that chemical properties of this material can vary widely from source to source (Evans et al. 1996).”

So at closer scrutiny we find out that there is a lot of data to have to consider when planning to use coir as a growing medium.

Coir is essentially cellulose and lignins, but these are richly electronegative molecules that will “trap” any positively charged atoms that are in solution. After some time absorbing nutrients, this cation-trapping ability of coir, also called cation exchange capacity (CEC), becomes saturated, since the coir’s cellulose has a limit or “capacity” for how many cations it can hold at any given pH. The adsorptive capacity of coir is high; there is a lot of surface-area in the granular structure of coir, and the electronegative cellulose fibres have a strong effect on all dissolved cations.

These cations are not really trapped, as they will “exchange” for other cations in solution. CEC changes with pH; since the hydrogen ion or “H+”, the element that pH measures, is it self a very small cation it is also attracted to the electronegative cellulose in coir.

Under acidic conditions many more H+ atoms are in solution, and these will displace the other cations readily from the coir, pushing the ionically bound salts on the cellulose back into solution. Sudden drops in pH (which means a rise in H+ concentration) can flash-release large amounts of potassium (K+) from the cellulose of coir.

Modern techniques for scientific analysis such as X-ray crystallography have been applied to coir, to determine the exact molecular structure of the cellulose. In an article called “Radial Distribution Function Analysis of Coir Fibre” published in the Journal of Material Science, vol.28 (1993) scientists reports the following:

“Coir is mainly a multicellular fibre which contains 30 to 300 or more cells in its cross-section. Cells in natural fibres like coir refer to the crystalline cellulose arranged helically in a matrix consisting of a non-crystalline cellulose-lignin complex. Coir has several valuable physical properties which stem from its structure. Among the most useful properties, mention may be made of length, fineness, strength, rigidity, wettability, resistivity, ...”.

This kind of analysis reveals that coir is mainly helically formed cellulose bundles. It’s inside this cellulose where roots will be trying to uptake solubilised nutrients. Cellulose fibres contain oxygen atoms that are “electronegative” and ionically bond to nutrients that have positive charges (cations). Monkey Juice is intended to keep a balance of these cations always in solution, no matter how strong the adsorptive effects of the cellulose in new and aged coir actually is.

These material scientists treated coir to heat, alkali and to “mercurization” to change the distances between the atoms of carbon hydrogen and oxygen in the coir cellulose before subjecting the coir samples to a focussed beam of X-rays. This energy then gets scattered or “diffracted” by the coir cellulose’s molecular structure, and a photograph is made of this pattern. From this the scientists can give these kinds of descriptions of the exact structure of coir, at the atomic level:

“The observed values of the interatomic distances do not exhibit any considerable change with a rise in the temperature of thermal treatment, as seen in Table III. Variation of coupling constant and r.m.s, displacement do not follow, in general, any regular pattern. However, in the case of first two interatomic distances, which play the most dominant role in bonding, there appears to be a downward trend in general up to around 120 Deg.C with a tendency to increase thereafter. For higher interatomic distances, where the order is likely to be less, the r.m.s, displacement values are increasing steadily with temperature, as expected, whereas the coupling constants vary without showing any regularity.”

X-ray crystallography data obtained from on coir is not everybody’s cup of tea.! To translate this: coir is a very resilient and strong fibred material. It can be subjected to the most abusive treatments of temperature and chemicals, but its molecular structure, the complex cellulose fibres, stays intact!

When shining X-rays onto coir that has been heated or into which alkali or mercury has been absorbed, scientists compare the before and after changes on parameters that make up the formula called a radial distribution function or RDF. An X-ray crystallography machine prints out this RDF on a chart. The RDF can be shown as a graph with a sloping line reaching a peak. These changes in the RDF give a measure of atomic structure of coir. The reader is referred to a link for more on RDF which can be found here.

These material scientists really have only analyzed aspects of the physical strength of coir, subjecting it to the most torturous of treatments and then observing the changes in the X-ray diffraction shown in the RDF graph. But growers appreciate other aspects of Coir as well. And in the more detailed technical descriptions the scientists give about coir we can recognize these other traits too. They continue to describe their results:

“Here also it is observed, in general, that the coupling constant (part of the RDF) attains a lower value at around 120 deg.C as compared to other values. This behavior is, possibly, due to expulsion of water molecules from the inter-chain space around this temperature which makes it a far more favorable conformation. It has been reported by Varma et al. [1, 2-1 that weight loss observed between 40 and 150 deg.C is due to evaporation of absorbed water.”

We growers certainly appreciate coir for its wettability and its water holding capacities! These scientists heated the coir to 150 deg C still observing water being evaporated! They continued to soak in mercury, and alkali, then bombarded it with X-rays and looked at what happened to the coir’s atomic structure:

“The conformation of the bonds in the ligno-cellulose complex at around 120 deg.C appears to be the most compact, which is likely to increase the mechanical strength of the fibre at this temperature…. Mercerization has very little effect on interatomic distances as seen in Table IV. Ottet al. [18] and Clegg [19] have reported dimensional changes in cotton fibre on mercerization. That occurs, possibly, due to shrinkage of the interlayer distance due to mercerization. The possible reactions [18] between the alkali and the different constituents of coir fibre are that cellulose can absorb alkali from an aqueous solution and the absorbed alkali can be removed by soaking in water; the subsequent drying 'results in a change in physical properties without altering the chemistry of cellulose. Therefore, interatomic distances are not expected to show any significant change due to mercerization.”

Well, we growers knew that! Coir holds its physical properties intact, with very few changes occurring at the atomic level, under all sorts of conditions. Coir could withstand X-ray bombardment and chemical assault and still present the physical properties ideal for growing.

As we growers also appreciate, coir will adsorb and the release cations (mercury is a large cation!) and alkali like an intense molecular sponge. Growers appreciate already, that this is a unique property of coir that must be both exploited and adjusted for. Coir’s high CEC in an ideal pH range on top of its virtually indestructible cellulose composition makes perfect sense as a growing medium.

Growing with Coir:

The success of each grower’s efforts to maximize yield and quality are a balance of numerous inputs, and coir is growing medium that permits this if we recall the unique properties of coir. According to the researchers at the University of Florida, Ft Lauderdale:

“The following qualities of coir dust make it a very good growing medium: 1) high water holding capacity equal or superior to sphagnum peat, 2) excellent drainage, equal to or better than sphagnum peat, 3) absence of weeds and pathogens, 4) greater physical resiliency (withstands compression of baling better) than sphagnum peat, 5) renewable resource; no ecological drawbacks to its use, 6) decomposes more slowly than sedge or sphagnum peat, 7) acceptable pH, cation exchange capacity and electrical conductivity, and 8) easier wettability than peat.”

For example scientists studying this have used petunias as a model to develop a fertigation regimen adjusted for coir. From Alan Meerow’s report comparing peat to coir we find these results discussed:

“Handreck (1993) tested growth of Petunia x hybrida 'Celebrity Salmon' in 5.6:1 (v:v) mixes of either Malaysian coir dust, Sri Lankan coir dust, or a sphagnum from Sakhalin, Russia and silica sand. He observed equal growth when all three mixes were adjusted to pH 6 and total plant nutrients were supplied, but varying performance with changes in nutrient regime. He concluded that plants in coir dust-based media require more Ca, S, Cu and Fe, but less K, than those grown in peat. He also observed greater immobilization of soluble nitrogen with coir dust than peat, an observation confirmed by Cresswell (1992).”

This is the experience that has been replicated by growers all over the world using modern processed, horticultural grade coir.

Author and scientist Alan Meerow at the University of Florida Fort Lauderdale Research Center did research on coir vs. peat moss and reported the following:

“I tested the efficacy of coir dust as a peat substitute in replicated trials at the University of Florida Fort Lauderdale Research Center (Meerow, 1994, 1995). An ixora, an anthurium, majesty palm, and pentas were grown in container media that differed only in the peat fraction (40%). One mix utilized sphagnum, the second Florida (sedge) peat, and the third, coir dust. The pentas, ixora and majesty palm all grew much better in the coir dust mix than in sedge. Interestingly, the anthurium grew almost as well in the sedge peat mix as in the coir dust. The pentas, majesty palm and anthurium grew equally well in the coir dust medium as in the sphagnum medium. Only the anthurium showed slightly better top growth in the sphagnum mix, a factor I attributed to nitrogen lock-up by the coir dust.”

These are interesting results, but can be explained further when noting that the fertilizer incorporated into these experimental soil mixes was used at a relatively high rate. In essence these results show that when using a rich regimen of fertilizers, flowering plants such as ixora, also called the Jungle Flame flower, out performs growth on peat based soil when grown with coir. This experiment used a fertilizer blend roughly approximating the specific needs of coir. The author reports using 9.5kg / m^3 of slow release fertilizer (Osmocote 17-2.3-10) along with generous micromax and liming rates.

This fertilizer was mixed into the soil, and in a warm climate this kind of controlled release fertilizer will release its nutrient charge faster. For some species, this could even be a “too-hot” fertilizer rate if the medium he was using had a much lower cationic exchange capacity than coir.

Continuing with the experiments growing in peat and Coir, the University of Florida researchers also noted that coir based growing media had less tendency to compact, and loose air spaces and porosity compared to peat:

“The sedge peat-based medium had the greatest percent air space and the lowest water-holding capacity of the three media at the initiation of the trials, but at termination, showed considerable reversal of these parameters. The coir dust-based medium showed the least change in these parameters over time. The higher initial air porosity of the sedge-based medium may have been conducive to better initial root growth of the anthurium, as this plant is epiphytic in nature. More informally, (we) noticed that seeds sown in a 1:1 (v:v) mix of coir dust and perlite seem to develop larger root systems than those germinated in 1:1 sphagnum and perlite. The material holds up very well under mist, and seems to support less algae growth than sphagnum. (We have) been further impressed by the ease with which coir dust re-wets after it has been thoroughly dehydrated. I found it takes about 3 hours to "fluff out" 20 bricks of 9:1 compressed coir dust. Claims have been made that coir dust is also slightly antibiotic, and thus may inhibit root pathogens, but this is, to my knowledge, undocumented.”

Alan Meerow concludes his review of the coir industry mentioning the world wide availability of coir:

“Currently Sri Lankan coir dust is available in bulk from several sources in the United States and Canada at this time… Scotts, Inc. has begun to offer commercial horticultural media containing coir dust. Local soil mix companies in Florida have been reluctant to offer coir dust until it can be processed exactly as they do sphagnum peat. Many companies charge a premium to rehydrate the bales of coir dust and incorporate the material into a custom medium.

Compared to Asia, there is little coir production in tropical America, and, consequently, low supplies of coir dust. Growing acceptance of the material in the horticultural marketplace is likely to change this, however, and we may see start-up companies in our own hemisphere attempting to compete with Sri Lanka and the Philippines in the future. Coir dust may well be a product whose time has come. The key issues in developing widespread use of this material in American horticulture will be price (currently equal to sphagnum peat) and insuring consistent quality of the coir dusts that enter the marketplace (Evans et al. 1996).”

knna

Great reading! Thanks a lot, OldBasilisk

This fully agree with my experience. Growing in coco coir needs higher levels of Ca and S than in other media. And a bit higher in N. About Cu and Fe, most formulas used more than required, so no problem with this.

Thge CannaCoco nutes follow this advice, except for the S level (very low, i had a S deff the first time i used it), while the GH is probably short in Ca and N for this medium. Anybody have the Hesi Coco nutes profile?

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OldBasilisk

This is all I could find on Hesi... someone own a bottle? If so, plug in the numbers here: CannaStats - Nutrient Profiles for Cannabis

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