MAP or TSP: the choice that is really about nitrogen
MAP and TSP are the two concentrated phosphate fertilizers, and buyers compare them constantly. The comparison is simpler than it looks, because the two products differ on one structural point and everything else follows from it: MAP carries nitrogen and TSP does not.
The numbers
MAP 11-52-0 — 11% N, 52% available P2O5, acid-forming. TSP 0-46-0 — no nitrogen, 44–46% available P2O5, plus calcium and a small amount of sulphur.
On phosphate concentration MAP is ahead by six points. On everything else — the way it is bought, priced and used — the difference is the nitrogen.
The cost structure is different, not just the price
This is the part buyers miss. MAP and TSP are not made the same way, and their costs respond to different markets.
MAP is phosphoric acid plus ammonia. Its cost therefore responds to both the phosphate and the nitrogen markets. When ammonia rises, MAP’s cost rises with it.
TSP is rock attacked with phosphoric acid, with no ammonia at all. Its cost responds to rock and sulphur, and not to nitrogen.
That means the two products separate in price when nitrogen and phosphate markets diverge. In a period of rising ammonia, TSP becomes relatively cheaper per unit of P2O5 and the gap widens. In a falling nitrogen market, MAP recovers its advantage.
For a buyer, this is an opportunity rather than trivia: TSP is the product that isolates phosphate exposure. If you have a view that phosphate is firm and nitrogen is soft, TSP expresses it.
When TSP is the right answer
When the nitrogen budget is already met. A programme built on urea or ammonium sulfate has its nitrogen planned. Adding MAP brings 11% nitrogen that has to be counted, and on a high rate of phosphate that nitrogen is not trivial.
When extra nitrogen is actively unhelpful. Late applications, crops where vegetative growth is already excessive, and situations where lodging risk matters. Phosphate without nitrogen is a real agronomic requirement and TSP is the product for it.
When calcium is wanted. TSP carries calcium alongside the phosphate, which suits some soil conditions and some crops.
When the phosphate has to be applied at a high rate. On a phosphate-deficient soil being corrected, the volume of product applied is large, and the nitrogen that comes with MAP at that volume can be more than the crop wants.
When MAP is the right answer
When the phosphate will be blended. MAP’s granule is designed for blending and it is compatible with urea. TSP granulates well too, but the MAP granule is the more standard blending input.
When concentration matters. On a long freight leg, 52% against 46% is a real difference in cost per nutrient unit.
When nitrogen at planting is useful. A starter application that supplies both nutrients in one pass is simpler and cheaper than two products.
Storage and handling
Both are non-hygroscopic relative to DAP and both store well. TSP’s handling issue is free acid: excessively acidic material corrodes mild steel equipment and degrades bag liners. The free acid content belongs on the COA with a limit in the contract, and it is more of a concern with TSP than with MAP.
MAP’s handling issue is granule strength. A granule that crumbles produces fines, and fines dust in a spreader and segregate in a blend.
A note on SSP
Buyers comparing MAP and TSP often end up looking at SSP as well, because it is cheaper per tonne. SSP is a different proposition: 16–20% P2O5, plus 11–12% sulphur and substantial calcium. It is the right product when sulphur is genuinely deficient. It is the wrong product when it is bought purely on price per tonne, because you will need roughly two and a half times the tonnage to deliver the same phosphate, and you will pay freight on the difference.
Deciding
Ask three questions:
- Is my nitrogen already planned? If yes, TSP avoids disturbing it.
- Is the material going into a blend? If yes, MAP is the more standard input.
- How long is the freight leg? The longer it is, the more MAP’s concentration is worth.
If the answers point different ways, compare delivered cost per tonne of P2O5 — and remember that TSP’s price moves with rock and sulphur while MAP’s moves with ammonia as well.
Product properties described here are stable. Prices are not quoted; ask the export desk for a comparison against your cargo.
Questions buyers ask
When should I buy TSP instead of MAP?
When the nitrogen budget is already met by another product and adding more would push it past the target, or when the phosphate has to be applied without stimulating vegetative growth. TSP delivers phosphate and calcium only.
Is TSP cheaper than MAP?
Usually per tonne of product, because it does not carry ammonia cost. Per unit of P2O5 the two are often closer than the headline suggests, and the answer changes with the nitrogen and sulphur markets. Compare delivered cost per tonne of P2O5.
Does TSP contain sulphur?
A small amount, unlike SSP which carries 11–12%. If sulphur is a requirement, SSP is the product designed for it; TSP should not be bought for its sulphur content.
Need a price for a specific cargo?
Give us the product, grade, quantity and discharge port, and the quotation comes back with the specification basis stated.