MAP (monoammonium phosphate) is one of the most concentrated phosphorus fertilizers on the market. Its key advantage: 52% P₂O₅ — the highest of all widely used solid fertilizers. This allows MAP to deliver more phosphorus at minimum weight, resulting in significant transport savings at scale.

MAP Composition: What is 12:52

MAP (monoammonium phosphate, NH₄H₂PO₄) is produced by neutralising phosphoric acid with ammonia. Grey-white granules, highly soluble in water.

  • Nitrogen (N): 12% — ammonium form only (NH₄⁺). No nitrate nitrogen.
  • Phosphorus (P₂O₅): 52% — fully water-soluble and plant-available.
  • Potassium: none. Apply separately if required.
  • Solution pH: 5.5–6.0 — weakly acidic. This is critically important for alkaline soils.

MAP, DAP and Superphosphate: Comparison of Three Phosphorus Fertilizers

MAP
NH₄H₂PO₄ · NP 12:52
N12%
P₂O₅52%
Solution pH5.5–6.0
Sulphur (S)none
N formAmmonium
StandardGOST 18918-85
DAP
(NH₄)₂HPO₄ · NP 18:46
N18%
P₂O₅46%
Solution pH7.5–8.0
Sulphur (S)none
N formAmmonium
StandardGOST 19691-84
Double Superphosphate
Ca(H₂PO₄)₂ · P 43–46%
Nnone
P₂O₅43–46%
Solution pH3.0–3.5
Sulphur (S)12–13%
N formnone
StandardGOST 16306-85

Why MAP's pH Matters

This is MAP's key practical advantage over DAP on certain soil types. Here is the reasoning:

On calcareous and alkaline soils (chernozems, grey soils, pH 7.5–8.5), phosphorus from DAP (solution pH 7.5–8.0) quickly forms insoluble compounds with calcium (phosphate fixation/retrograde). MAP at pH 5.5–6.0 creates a mildly acidic environment around the granule, slowing fixation and keeping phosphorus available for longer.

On acid soils (pH below 5.5) the pH difference between MAP and DAP is practically irrelevant — both fertilizers perform similarly.

MAP preferred
Chernozems, calcareous soils, grey soils, chestnut soils (pH 7.0–8.5). MAP's weakly acidic pH slows phosphate fixation — higher efficiency.
DAP preferred
Podzols, grey forest soils, acid soils (pH 5.0–6.5). On acid soils, DAP's higher nitrogen is convenient; pH is not decisive.
MAP in-furrow — universal
For starter in-furrow application at sowing, MAP is preferred on all soil types — its mildly acidic pH is safer for seeds.
Superphosphate where sulphur is needed
On light soils with sulphur deficiency, superphosphate provides additional benefit from S 12–13%. MAP contains no sulphur.

MAP Application Rates by Crop

Crop Base application, kg/ha In-furrow at sowing, kg/ha Provides P₂O₅, kg/ha
Winter wheat 80–130 15–25 42–68 (base)
Spring wheat 70–120 15–20 36–62
Barley 70–110 15–20 36–57
Maize 100–160 20–30 52–83
Sunflower 80–120 15–25 42–62
Winter rapeseed 90–140 15–25 47–73
Sugar beet 180–240 — 94–125
Potato 150–200 20–30 78–104
Vegetables 100–180 15–25 52–94

Note: MAP supplies only phosphorus-nitrogen nutrition. Additional nitrogen is applied with ammonium nitrate, urea or UAN. Potassium — with muriate of potash or potassium sulphate separately.

Calculating MAP Dose from Phosphorus Rate

MAP contains 52% P₂O₅. Formula for converting P₂O₅ rate to MAP dose:

MAP dose (kg/ha) = P₂O₅ rate (kg/ha) ÷ 0.52

Example: P₂O₅ rate 60 kg/ha → MAP dose = 60 ÷ 0.52 = 115 kg/ha

MAP also supplies 115 × 0.12 = 13.8 kg/ha nitrogen — account for this when calculating additional nitrogen fertilizer doses.

In-Furrow MAP Application at Sowing: Practice

In-furrow (starter) MAP application is one of the most effective agronomic practices. A small dose of phosphorus placed directly under the seed dramatically improves early root system development and seedling emergence in the first 2–3 weeks — a period when roots are too small to absorb phosphorus from the base soil layer.

MAP advantages over DAP in-furrow

  • Weakly acidic pH (5.5) — safer for seeds on neutral and alkaline soils
  • Less nitrogen (12% vs 18%) — lower risk of osmotic stress at seed contact
  • More phosphorus (52% vs 46%) — less granule volume in the furrow at the same P₂O₅ dose

Practical limits for in-furrow application

  • Maximum in-furrow rate: no more than 25–30 kg/ha MAP. Exceeding this causes osmotic stress — delayed emergence, reduced field germination
  • With combined drills (seed + fertilizer in one furrow) — rate no more than 20 kg/ha
  • With split openers (seed and fertilizer at different depths) — rate up to 30 kg/ha

MAP in the Nutrition System: Combining with Other Fertilizers

MAP is the phosphorus-nitrogen component of the nutrition system. Supplementation is needed for complete crop nutrition:

Missing element Recommended addition Timing
Nitrogen (main dose) Ammonium nitrate, urea, UAN-28/32 Spring + top-dressings during growing season
Potassium Muriate of potash (autumn), potassium sulphate (chlorine-sensitive crops) Autumn ploughing or spring
Sulphur Ammonium sulphate, potassium sulphate or elemental sulphur Base application
Full NPK (simplified) NPK 16:16:16 instead of MAP + separate K and N Single pass, base application
MAP — best choice when…
  • Alkaline or calcareous soils (pH > 7.0)
  • Maximum P₂O₅ content needed at minimum N
  • Starter in-furrow application — lower seed scorch risk
  • Nitrogen already planned with separate fertilizers
  • Precise N and P management by soil analysis
DAP — best choice when…
  • Acid and neutral soils (pH 5.0–7.0)
  • Higher nitrogen needed in starter dose
  • Soils without risk of phosphate fixation
  • One NP fertilizer instead of MAP + separate nitrogen
  • No difference in cost per unit P₂O₅

Economics: Comparing Phosphorus Cost in MAP and DAP

Compare cost per 1 kg P₂O₅, not price per tonne. Example calculation:

  • MAP at $260/t: 260 ÷ 520 = $0.50/kg P₂O₅ + 12 kg N per tonne
  • DAP at $280/t: 280 ÷ 460 = $0.61/kg P₂O₅ + 18 kg N per tonne

In this example MAP is 18% cheaper per unit of phosphorus. However DAP supplies more nitrogen per tonne (18% vs 12%), which must be factored into the total cost of nitrogen-phosphorus nutrition.

Need MAP wholesale? We supply MAP 12:52 with GOST documentation worldwide from 1 tonne.