How to read a fertiliser technical data sheet: a data sheet says four things, and it pays to read them in this order. What it contains (the analysis and the form of each nutrient), what it is like (density, pH and physical state), how it is used (dosage by route, timing and mixes) and what backs it (safety and suitability for use in organic farming). Read this way, it allows products to be compared by their content and not by their name. We do it here on our own data sheets, with the real figure in front of us.
What a technical data sheet is and how it differs from the label and the SDS
Three documents accompany a fertiliser and each answers a different question. The label on the container identifies it: name, declared analysis and precautionary statements. The technical data sheet develops what the label summarises: composition, physical properties, dosage by route, crops, compatibilities and storage. The safety data sheet (SDS) describes safe handling and the hazard classification.
The SDS is where the statements later repeated on the data sheets come from: P102, “Keep out of reach of children”, and P270, “Do not eat, drink or smoke when using this product”. The classification comes from there too: the BORO data sheet says “not classified under Regulation (EC) No 1272/2008” (the CLP Regulation).
Some manufacturers only hand over the technical data sheet after you fill in a form. We publish each product’s data sheet in full, in six blocks: Safety · Composition · Dosage · Crops · Mixing · Organic suitability. This guide goes through them one by one.
Guaranteed analysis: what the percentage means
The guaranteed analysis is the nutrient content we declare, and it is read as three pieces of data: how much there is, in what chemical form and in what unit.
% w/w versus % w/v
The % w/w (weight/weight) is the nutrient present relative to the weight of the product; the % w/v (weight/volume), relative to its volume. A solid only has w/w; a liquid usually carries both, and what separates them is the density.
The UNIVERSAL data sheet declares “Total potassium oxide (K2O) — 1.00% w/w · 1.01% w/v” and “Density: 1.01 kg/L”: multiplying the w/w by the density gives the w/v the data sheet publishes. In CALCIO 880 the gap between the two figures grows with the density: “Calcium oxide (CaO), total — 35.00% w/w · 61.25% w/v”. FÓSFORO 20 LÍQUIDO, for its part, declares only the w/w figure: “20.00% w/w”. Rule of thumb: to dose per litre of product, use the w/v; to compare two formulations, the w/w.
Oxide or element
Phosphorus and potassium are by convention declared as oxides (P2O5 and K2O); calcium or iron may appear either way, and our data sheets usually give both on consecutive lines. CALCIO 880 declares “Calcium oxide (CaO), total — 35.00% w/w” and “Calcium (Ca), total — 25.02% w/w”. HIERRO declares “Total iron (Fe) — 6.50% w/w” and “Total iron oxide (FeO) — 8.38% w/w”. POTASIO K20 declares “Total potassium oxide (K2O) — 20.00% w/w” and “Total potassium (K) — 16.6% w/w”.
The oxide figure is always higher because it counts the oxygen; what goes wrong is comparing the oxide of one product with the element of another.
The three numbers of an NPK
The three numbers in the name are the nitrogen, phosphorus and potassium analyses, in that order. NPK 9-4-4 declares “Total nitrogen (N) — 9.00% w/w”, “Total phosphorus (P2O5) — 4.00% w/w” and “Total potassium (K2O) — 4.00% w/w”.
What the three numbers do not say is the rest of the data sheet. NPK 7-7-7 also declares “Total organic matter — 69.30% w/w”, “Total amino acids — 33.45% w/w” and “C/N ratio — 5.74”.
The form of the nutrient matters as much as the amount
Nitrogen is where it shows best. NITRÓGENO 16 declares “Total nitrogen (N) — 16.00% w/w” and splits it into “Organic nitrogen — 15.80% w/w” and “Ammoniacal nitrogen — 0.20% w/w”. NUTRIPLUS 8 splits its “Total nitrogen (N) — 8.00% w/w” into three lines: “Ammoniacal nitrogen — 0.10% w/w”, “Ureic nitrogen — 0.50% w/w” and “Organic nitrogen — 7.40% w/w”.
Each form speaks of the origin of the nitrogen. Ammoniacal is ammonium, ureic is urea and organic is bound to organic molecules, which can be recognised in the neighbouring lines: NITRÓGENO 16 declares “Total amino acids — 98.60% w/w”, “Total organic matter — 91.50% w/w” and “C/N ratio — 3.29”. Release rates are another matter and we do not deal with them here.
Density, pH, physical state and solubility: the handling data
The physical properties do not say how much nutrient there is, but how the product is handled. The density converts litres into kilograms: FÓSFORO 20 LÍQUIDO declares “Density: 1.18 g/mL” and NPK 5-5-5 LÍQUIDO, “Density: 1.25 ± 0.01”.
The pH anticipates mixes and pre-dilutions. FÓSFORO 20 LÍQUIDO declares “pH: 0.50”; NPK 5-5-5 LÍQUIDO, “pH: 4.40 ± 0.5”; NPK 3-3-10 LÍQUIDO, “pH: 7.90 ± 0.5”; CALCIO 880, “pH: 8.00”. A high pH brings a handling instruction worth reading before opening the tank: HUMIC FULVIC+ALGAS warns “owing to its high pH, pre-dilute before pouring into the irrigation or spray tank; add an acidifier”.
The physical state and the solubility say how the spray mix is prepared: HIERRO is a “liquid, brown” and is measured by volume; NPK 9-4-4 is a “solid powder, brown” and is weighed. A powder is dosed in grams or kilograms and a liquid in litres, and that changes the unit of the whole dosage table.
Dosage and directions for use: read the route and the unit before the number
In a dosage table, the number is the last thing to look at. First the route (foliar or fertigation) and then the unit, because each route has its own. The BORO data sheet shows it. By the foliar route, the maintenance dose in fruit trees is “3-6 L/1,000 L per application” and in vegetable and arable crops “3-4 L/1,000 L per application”: litres of product per thousand litres of spray mix. By fertigation the same data sheet changes unit and speaks of area: in severe deficiency, “up to 4 applications (6 to 8 L/ha)” in fruit trees and “up to 4 applications (1-2 L/ha)” in vegetable and arable crops, with a general note: “split into a maximum of 3 L/ha, at 10-15 day intervals”.
The second reading is the difference between maintenance, the base dose when there is no diagnosed deficiency, and severe deficiency, the regime when there is one. In our data sheets what changes above all is the number of applications: CALCIO 880 declares by the foliar route “2-3 L/1,000 L per application; severe deficiency: up to 4 applications”.
Solids have another scale: NPK 9-4-4 is dosed by the foliar route at “150 g/100 L” in fruit trees and “200 g/100 L” in vegetable crops, and by fertigation at “2 kg/ha per application” in fruit trees.
Several data sheets close with a warning that is part of the dosage: “doses are general recommendations: they depend on the crop, phenological stage, level of deficiency and soil type”, always “under technical advice”. NPK 7-7-7 writes it, and NITRÓGENO 16 repeats it in its own words: doses “are general recommendations according to crop, phenology, deficiency and soil”.
Crops, timings and compatibility
A crop appearing on the data sheet means we publish a dose and timing for it; a crop not appearing means we do not publish that data, not that the product does not work for it. Timings are read on the same data sheet: BORO writes “vegetative stage, post-flowering and stages of highest vegetative activity (fruit set, ripening)”.
Compatibility is the line that saves the most trouble. HIERRO warns “do not mix with phosphate products”; POTASIO K20, “do not mix with products containing phosphorus and/or calcium”; HUMIC FULVIC+ALGAS, “do not mix with highly alkaline products”. And when the data sheet is silent on a mix, the rule is the one NITRÓGENO 16 writes: “phytotoxicity test on a small plot before large-scale application”.
Storage and shelf life: what the data sheet warns of and almost nobody reads
It is the least-read block and the one that warns of what changes the product’s shelf life. CALCIO 880 warns: “if stored, shake at least once a month for ≥1 hour; otherwise the shelf life is limited to 5-6 months from manufacture owing to settling of the Ca (reversible with hot water and shaking)”. FÓSFORO 0-20-0 carries the same warning for settling of the phosphorus.
The conditions are specific: NITRÓGENO 16 asks you to “store at 5-35 °C, avoid freezing, heat, moisture and direct sunlight” and declares “Shelf life: 2 years”; NUTRIPLUS 8 adds “do not store below 16 °C”. And one sentence is repeated on many of our data sheets: “physical characteristics and appearance may vary owing to the organic nature of the product”.
Suitability for organic farming: which line to look for and what it means
It is the sixth block and has a fixed wording: “product suitable for use in organic farming”, followed by the document that backs it. It is listed in the annex of the ECOCERT S.A.S input attestation No. 245895/29/290920251037 (“EU - Inputs Attestation” programme, Regulations (EU) 2018/848 and (EU) 2021/1165), valid until 31 March 2027.
There is only one thing to check: that the exact name of the product appears in the annex of that document. A logo on the container is no substitute. The full documents are in the input attestations and the step-by-step procedure in how to check whether an input is suitable for organic farming.
How to compare two data sheets without trusting the name
With all of the above, comparing two data sheets is a six-step procedure and none of the steps starts with the trade name:
- Same unit. Both analyses in % w/w; if a data sheet only gives w/v, convert it to w/w with its density.
- Same nutrient and same form. Fe with Fe, not FeO with Fe; K2O with K2O; for nitrogen, total with total and breakdown with breakdown.
- Cost per unit of nutrient, not per litre. Divide the price of the pack by the amount of nutrient it carries, not by its litres.
- Declared route and dose. That a dose exists for your route and your crop, in its unit.
- Incompatibilities and pH. What cannot be mixed with what you already apply and whether you need to pre-dilute or acidify.
- Suitability for organic farming. The product name in the annex of a valid attestation.
Anyone who learns to read a fertiliser technical data sheet this way stops comparing names and starts comparing nutrients.
Frequently asked questions
What does % w/w mean in a fertiliser?
It is the nutrient present relative to the weight of the product, which is why it serves to compare formulations. The % w/v is relative to volume and only makes sense in liquids: UNIVERSAL gives both, “1.00% w/w · 1.01% w/v”.
Why does calcium appear as both CaO and Ca?
They are two ways of expressing the same amount: the oxide includes the oxygen and its figure is higher. CALCIO 880 declares “35.00% w/w” of CaO and “25.02% w/w” of Ca; when comparing products, use the same one for both.
What is the difference between the technical data sheet, the label and the safety data sheet?
The label identifies the product; the technical data sheet details composition, dosage, compatibilities and storage; the safety data sheet describes the hazard classification and safe handling.
What does “severe deficiency” mean in the dosage table?
That the regime is for a crop with a deficiency, as opposed to “maintenance”, the base dose. In CALCIO 880 the difference lies in the applications: “up to 4 applications”. The deficiency is confirmed by leaf analysis and technical advice.
Where do you check that a fertiliser is suitable for use in organic farming?
In the annex of the input attestation that backs it, looking for the exact name of the product, and in the current version served by the issuing body. Our data sheets carry the document number.
All 26 data sheets are published in full, with those six blocks, in the full catalogue. If a line is not clear with the product in front of you, the technical enquiry exists for that.