What to ask a coco peat supplier before you buy a container

A container of coco peat is a large purchase made on a short document. The specification is usually a handful of numbers, most quotations look interchangeable, and the difference between a good batch and an expensive one is invisible until it is in a tray with a crop on top of it.

This is written for two readers at once. The procurement manager needs to know what to put in the purchase order and what to reject at the gate. The grower needs to know what the numbers do in the root zone. Both need the same set of questions.

What separates a supplier from a trader

It is not size, and a trader is not automatically the wrong answer, since plenty of good material is sold by intermediaries. The distinction is whether the seller can pass a technical question back to the mill and return with a specific answer, or whether every answer arrives as a reassurance.

The practical test is three questions in one message: which extraction method your EC figure is quoted on, what the moisture content was at loading and how it was measured, and whether a sealed sample from this lot is retained. A seller in control of their supply chain answers all three inside a day. A seller who is not answers the first with a number, the second with a shrug and the third with silence.

The questions that do the work

1. Which extraction method is the EC quoted on. A 1:1.5 volume extract and a 1:5 water extract give very different numbers for the same material. Name the method in the purchase order and require testing by it rather than accepting a conversion.
2. Is the batch washed only, or washed and buffered, and buffered with what. Ask for the agent, the contact time and confirmation that a rinse followed. Washed and buffered used as a single phrase with no detail behind it usually means washed.
3. What is the compression ratio and the expansion yield. Ask for litres of hydrated and drained medium per block at a stated water temperature. A standard 5 kg block yields roughly 65 to 75 litres depending on compression ratio and grade.
4. What is the particle size distribution, including the dust fraction. Ask for sieve sizes and the percentage passing the smallest. Dust is the fraction nobody quotes and everybody suffers from: it collapses air-filled porosity, blinds filter fabric and blocks drippers.
5. What is the moisture content at loading and how is it verified. Blocks are commonly loaded around 15 to 20 per cent moisture. Higher means you are paying freight on water and risking heating and mould in transit.
6. What are the sodium and potassium figures, separately, and the chloride. EC cannot distinguish them. Sodium is the agronomic risk, potassium quietly distorts a feed programme, and chloride matters on salt-sensitive crops.
7. What is the pH and how stable is it. Horticultural coir usually sits around 5.5 to 6.8 on the stated extract. Ask whether anything was added to adjust it, because treated material can drift back over months in storage.
8. What physical contamination controls exist. Sand and ash content, husk chips, stones, string and plastic all arrive in poorly screened material. Agree a maximum for sand or ash and a zero tolerance list for foreign objects.
9. Is there batch traceability, and is a sealed sample retained. A lot number matching the packaging, plus a retained sample held by both parties for an agreed period, converts a future dispute from an argument into a test.

A specification with numbers in it

A specification that a supplier cannot fail is not a specification. The following is the minimum set of lines worth enforcing, with ranges that should be narrowed to your crop and system rather than copied.

The documentation to require

• A certificate of analysis referencing the specific lot, not a typical analysis. The two look similar and only one describes the goods you bought.
• A certificate date falling after the production date of the lot. Paperwork predating the material it certifies is recycled paperwork.
• The testing laboratory named, with the method reference for each parameter, so the numbers can be repeated.
• A packing list giving block count, blocks per pallet and pallet weights, so the container can be reconciled at offloading.
• A moisture declaration at loading, which is a commercial document as much as a technical one.
• Phytosanitary documentation where the destination requires it, and treatment records for wood packaging. Requirements differ by destination country and belong in the pre-shipment checklist.
• The container number cross-referenced on the certificate and packing list, which catches consignment mix-ups before they become crop failures.
• A retained sample declaration: who holds a sealed sample from this lot, and for how long.

Taking a sample that represents the container

Most disputes about coir are unresolvable because the sample came from the first pallet inside the door. Material varies within a load, and door-side pallets are the ones most affected by transit humidity.

1. Take at least 8 to 12 increments spread across the load: front, middle and door, and from different heights within the stack.
2. Sample from inside the block rather than from its surface. Split a block and take material from the core, because surfaces gain and lose moisture in transit.
3. Combine the increments into one composite, mix it thoroughly and quarter it down to a laboratory sample of one to two litres.
4. Split the final sample into two identical sealed containers. One goes to the laboratory, one is retained. Both are labelled with the lot number, container number, date and the names of the people present.
5. Photograph the sampling: the container seal intact, the pallets sampled and the sealed samples. It takes minutes and it settles arguments.

On-site checks without a laboratory

• Weigh blocks. Take ten at random from different pallets and compare the average against the declared weight. A consistent overweight is moisture; a wide scatter is poor process control.
• Run a hydration test. Hydrate three blocks in a measured volume of warm water, drain freely for 30 minutes, then measure the litres produced. That is the yield you actually bought.
• Squeeze a handful of hydrated material. It should hold form and release a few drops, not a stream.
• Check EC and pH with a calibrated meter using the extract named in the specification. It will not replace a laboratory, but it catches a badly wrong consignment immediately.
• Use your nose and hands on the dry blocks. Sour or ammonia smells, visible mould or blocks that feel warm all point to wet storage and microbial activity.
• Look at the dust. Shake a litre through a fine sieve, or drop a handful into a clear jar of water. Material that clouds the water heavily is the fraction that will blind your drippers.
• Check for sand. Hydrate, stir and let it settle in a clear container. A distinct mineral layer at the bottom is ash content you paid freight on.
• Run a germination bioassay before committing a crop. Sow cress or lettuce in the new batch alongside a known good control. Poor or uneven germination at five to seven days flags salt or phytotoxicity while it is still cheap.

Container maths and what a load should yield

Compressed coir is weight-limited rather than volume-limited, which is the single fact that makes moisture content a commercial issue rather than a technical one.

A 40 foot high cube of compressed blocks commonly loads around 20 to 24 tonnes, with the ceiling set by the payload limit and by road weight limits at the destination rather than by container volume. At 5 kg per block that is roughly 4,000 to 4,800 blocks, and at 65 to 75 litres per block roughly 260 to 340 cubic metres of hydrated medium. The same arithmetic applies to bales and briquettes.

Now apply the moisture. A 22 tonne load at 18 per cent moisture carries about 18.0 tonnes of dry coir. The same 22 tonnes at 28 per cent moisture carries about 15.8 tonnes. That is roughly 2.2 tonnes less product, around 12 per cent, for identical freight, and the yield in litres falls with it. Nothing on the invoice will mention it.

The defence is to fix the basis of price. Either price per tonne at a declared maximum moisture content, with a stated adjustment if the delivered figure exceeds it, or price per cubic metre of hydrated and drained medium. A price per tonne with no moisture basis is not a price you can compare.

Lead times, Incoterms and what changes at the port

Lead time is not one number. Standard washed grades in compressed blocks move relatively quickly because they are produced continuously. Low EC washed and buffered grades sit in a queue, since washing, buffering, rinsing and drying are sequential steps, and drying is weather-dependent in producing regions, which is why moisture content and lead time move together seasonally. Custom blends and specified particle size splits add more. Order propagation grades with slack.

On Incoterms, the practical question is who controls the shipping and who carries the clock. Under FOB you nominate the line, control transit time and carry demurrage and detention on your own account. Under CIF or CFR the seller books the freight, which can mean a cheaper quoted rate against a slower routing with more transhipment. Under DAP or DDP the seller carries it to your door and the price contains a risk margin you cannot see. None is wrong; what is wrong is comparing an FOB price against a DAP price as if they were the same number.

At the port, three things change. Customs clearance and duty apply against the declared classification and value. Inspection may be triggered, and phytosanitary requirements differ by destination country, so confirm them before the container sails. And the free time clock starts, typically a number of days varying by line and contract, before demurrage and detention accrue. A dispute discovered at the port is expensive precisely because that clock does not stop while it is argued, which is the strongest practical argument for pre-shipment sampling.

The commercial traps

What to send with the enquiry

Most of the back and forth in a coir enquiry disappears if the first message carries the crop, the system, the container or bed depth, the irrigation water analysis, the volume and frequency required, the destination port or emirate, the delivery term you want quoted, and the required date.

With that, grade selection is largely determined and the quotation can carry real numbers rather than a headline price. Without it, every supplier quotes their cheapest grade, and the only thing you can compare is a number that does not describe what you will receive.