MAP 11-52-0 (this product) is a granular agricultural grade designed for direct soil application — broadcasting, side dressing, banding, and pre-plant incorporation. Granules dissolve gradually as irrigation or rainfall moves through the soil.

MAP 12-61-0 is a technical-grade water-soluble powder with 61% available phosphate (P₂O₅), formulated for complete dissolution in water. Use it for fertigation, foliar feeding, and hydroponic systems where a liquid-soluble phosphorus source is required.

For a deeper comparison, see our guide on choosing the best phosphorus fertilizer.

No. This granular grade is intended for soil application, not liquid feeding. It is not formulated for complete dissolution in water and will leave undissolved material that can clog fertigation systems, drip injectors, and stock tanks. For fertigation or foliar spraying, use MAP 12-61-0 (Water Soluble) instead.

Penn State Extension research supports approximately 100 lb/acre of 11-52-0 in a 2×2 starter band when soil fertility is adequate — that supplies about 11 lb N and 52 lb P₂O₅ per acre. On low-testing soils the rate can go higher, up to about 200 lb/acre, but with a hard ceiling: N + K₂O in the band must not exceed 70 lb/acre when placed 2 inches from the seed.

For in-furrow (direct seed contact), the rate is much lower — K-State Extension research caps salt-sensitive crops at approximately 6–8 lb N + K₂O per acre in seed contact, which translates to roughly 55–70 lb of 11-52-0 per acre in-furrow on corn at 30-inch rows.

Divide the P₂O₅ recommendation by 0.52. So to apply 60 lb P₂O₅/acre, you need 60 ÷ 0.52 = approximately 115 lb of 11-52-0 per acre, which incidentally delivers about 12.7 lb of N per acre (115 × 0.11).

The calculator above runs this math automatically and accounts for unit conversions (sq ft, row feet, acres).

Field crops: Spring application is preferred over fall, especially on soils with pH above 7.4, to minimize phosphorus fixation (per MSU Extension).

Vegetables: Work into soil before planting, then side dress when plants begin flowering. For root crops, apply at bed preparation.

Fruit trees: Apply in early spring before bud break, and optionally post-harvest to restore nutrient reserves. Split applications for young trees — 2–3 smaller doses are preferred over one large application.

Lawns: Cool-season grasses in early fall; warm-season grasses in late spring. Incorporate before seeding for new lawns.

Over time, yes — the ammoniacal nitrogen in MAP can contribute to gradual soil acidification as nitrification occurs. This may be beneficial on alkaline soils above pH 7.5 where high pH reduces phosphorus and micronutrient availability. On already-acidic soils (below pH 6.0), monitor pH periodically and apply lime if needed. A soil test before application is always recommended.

The acidifying effect is one of MAP's structural advantages on calcareous soils — the acidic reaction zone around each dissolving granule (pH 3.5–4.5) keeps phosphate plant-available where high pH would normally lock it up. Mosaic and UMN Extension both confirm MAP's advantage over DAP in soils above pH 7.

Calcium and phosphate ions react in concentrated contact to form insoluble tricalcium phosphate, which reduces the availability of both nutrients. Apply MAP and Calcium Nitrate 15.5-0-0 at separate times or in separate passes, and let irrigation water move them independently through the soil at normal dilution.

For crops with high calcium demand — tomatoes, peppers, squash — this means applying calcium nitrate as a separate side dress or as a properly-diluted soil drench rather than blending the two in concentrated solution. The same precaution applies to other calcium-containing fertilizers.

Coverage depends on application rate and method. General guidelines:

• 2 lb bag — trial / single bed prep
• 5 lb bag — small raised beds or container soil amendment
• 10 lb bag — typical home vegetable garden or flower beds
• 25 lb bag — established garden, small lawn, or multi-tree orchard
• 50 lb bag — field plots, large orchards, or commercial use (covers ~0.5 acre at 100 lb/acre starter rate)

Use the calculator above for precise amounts based on your area and crop type.

Crops with high phosphorus demand see the most benefit: flowering annuals (petunias, marigolds, zinnias), bulbs (tulips, daffodils), roses, fruiting vegetables (tomatoes, peppers, squash, melons), root vegetables (potatoes, carrots, beets, onions), and commercial field crops (corn, soybeans, cotton, small grains, tree fruits). For more on this, see our article on fertilizers that improve fruit yield.

Phosphorus-sensitive plants such as proteas and grevilleas should receive reduced rates or phosphorus-free alternatives.

No. MAP is a synthetic mineral salt produced by reacting anhydrous ammonia with phosphoric acid, then granulating the resulting monoammonium phosphate. It is not approved for certified organic programs. If you need an organic-certified phosphorus source, consider Bone Meal 3-15-0 or Fish Bone Meal 4-17-0 — both deliver phosphate alongside naturally-occurring calcium.