Nitrogen + Sulfur — Soil Acidifier

Best Ammonium Sulfate Fertilizer (21-0-0 + 24% S): Nitrogen & Sulfur That Lowers Soil pH Buy on Old Cobblers Farm

Two nutrients in one product. 21% nitrogen for growth plus 24% sulfur that actively lowers soil pH — the preferred nitrogen source for acid-loving plants and alkaline soils that need correction.

Updated April 2026 10 Products Compared By the Old Cobblers Farm Team

Old Cobblers Farm™ Wicked Growth Ammonium Sulfate 21-0-0 Fertilizer

by Conventional Fertilizer — Littleton, NH

21-0-0
N-P-K Ratio
"The only nitrogen fertilizer in the lineup that doubles as a soil acidifier. 21% N plus 24% sulfur delivers growth and pH correction in a single application — essential for blueberries, azaleas, and alkaline soil correction."
21%
Nitrogen
24%
Sulfur
2,500 ft²
Max Coverage / bag
4 Sizes
5, 10, 15, 20 lbs
🧪

21% Nitrogen + 24% Sulfur

Two critical nutrients in every granule. 21% nitrogen feeds the plant while 24% sulfur acidifies the soil, improves protein synthesis, and enhances flavor compounds in crops.

⬇️

Lowers Soil pH

Ammonium sulfate is inherently acidifying. Each application nudges pH downward — exactly what blueberries, azaleas, rhododendrons, and evergreens need to thrive.

🫐

Acid-Lover's Preferred N Source

Extension services recommend ammonium sulfate as the nitrogen source for acid-loving crops. It feeds the plant AND maintains the low pH they require.

🌿

Sulfur Deficiency Correction

24% sulfur addresses sulfur deficiency — increasingly common in modern soils. Sulfur is essential for protein formation, chlorophyll, and crop flavor development.

📦

1,000–2,500 sq ft Per Bag

At lawn rates, one 5 lb bag covers 1,000–2,500 sq ft. Efficient application for targeted acidification and nitrogen feeding.

🌾

Cool-Season Lawn Favorite

Preferred by turf professionals for cool-season lawns. Provides quick green-up with sulfur that improves soil structure and nutrient availability in alkaline soils.

Low Burn Risk vs. Urea

At 21% N, ammonium sulfate has a lower burn risk per application than 46-0-0 urea. Safer for direct application near plant roots and on established lawns.

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Trusted by 20,000+ Growers

Developed in Littleton, New Hampshire. Sold nationwide on Amazon, Walmart, eBay, and theoldcobblersfarm.com.

NPK Ratio21-0-0
Item FormGranular (crystalline)
Coverage1,000–2,500 sq ft (lawn) per 5 lb bag
CategoryConventional Fertilizer
TypeAll-Purpose NPK Blends
Sizes5 lb | 10 lb | 15 lb | 20 lb
NPK21-0-0
Nitrogen21%
Phosphorus0%
Potassium0%
Sulfur24%
FormGranular (crystalline)
Rate2–5 lbs / 1,000 sq ft (lawn)
MethodBroadcast or side-dress
Sizes5, 10, 15, 20 lb bags
Best ForAcid-loving plants, alkaline soil correction, lawns, blueberries
What We Love
Dual-purpose: 21% nitrogen + 24% sulfur in every granule
Actively lowers soil pH — ideal for acid-loving plants
Extension-recommended N source for blueberries and azaleas
Lower burn risk than 46-0-0 urea
Corrects increasingly common sulfur deficiency in soils
Worth Noting
Will acidify soil — not for already-acidic soils without testing
Single nutrient (N) — must pair with P and K products
Buy on Old Cobblers Farm →
Available in 5 lb | 10 lb | 15 lb | 20 lb
Feature Old Cobblers Farm™ Wicked Growth Ammonium Sulfate 21-0-0 Fertilizer Old Cobblers Farm Ammonium Sulfate Fertilizer Greenway Biotech Ammonium Sulfate Hi-Yield (VPG) Ammonium Sulfate Fertilizer Easy Peasy Plants 21-0-0 Ammonium Sulfate Simplot Best 21-0-0 AM Turfgrass Fertilizer LESCO Dark Matter Ammonium Sulfate Lawn Life Ammonium Sulfate Alpha Chemicals Water Soluble Ammonium Sulfate Seed Ranch Ammonium Sulfate Plant Food Supply Solutions SoluGreen Ammonium Sulfate Custom Hydro
NPK 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0 21-0-0
Form Granular (crystalline)
Coverage 1,000–2,500 sq ft (lawn) per 5 lb bag Not listed Not listed Not listed Not listed Not listed Not listed Not listed Not listed Not listed Not listed
Price / Size 5 lb | 10 lb | 15 lb | 20 lb $15-$35 $10-$30 $15-$20 $40-$60 $45-$55 $55-$60 $19-$30 $30-$80 $25 $35-$60
Our Take The only nitrogen fertilizer in the lineup that doubles as a soil a...
The Competition

Ammonium Sulfate Fertilizer

by Greenway Biotech
21-0-0
N-P-K
Sizes2-10 lb
Price$15-$35

Ammonium Sulfate

by Hi-Yield (VPG)
21-0-0
N-P-K
Sizes4 lb, 16 lb
Price$10-$30

Ammonium Sulfate Fertilizer

by Easy Peasy Plants
21-0-0
N-P-K
Sizes5 lb
Price$15-$20

21-0-0 Ammonium Sulfate

by Simplot Best
21-0-0
N-P-K
Sizes50 lb
Price$40-$60

21-0-0 AM Turfgrass Fertilizer

by LESCO
21-0-0
N-P-K
Sizes50 lb
Price$45-$55

Dark Matter Ammonium Sulfate

by Lawn Life
21-0-0
N-P-K
Sizes40 lb
Price$55-$60

Ammonium Sulfate

by Alpha Chemicals
21-0-0
N-P-K
Sizes5 lb, 10 lb
Price$19-$30

Water Soluble Ammonium Sulfate

by Seed Ranch
21-0-0
N-P-K
Sizes5-50 lb
Price$30-$80

Ammonium Sulfate Plant Food

by Supply Solutions
21-0-0
N-P-K
Sizes5 lb
Price$25

SoluGreen Ammonium Sulfate

by Custom Hydro
21-0-0
N-P-K
Sizes50 lb
Price$35-$60

🧪

21% Nitrogen + 24% Sulfur

Two critical nutrients in every granule. 21% nitrogen feeds the plant while 24% sulfur acidifies the soil, improves protein synthesis, and enhances flavor compounds in crops.

⬇️

Lowers Soil pH

Ammonium sulfate is inherently acidifying. Each application nudges pH downward — exactly what blueberries, azaleas, rhododendrons, and evergreens need to thrive.

🫐

Acid-Lover's Preferred N Source

Extension services recommend ammonium sulfate as the nitrogen source for acid-loving crops. It feeds the plant AND maintains the low pH they require.

🌿

Sulfur Deficiency Correction

24% sulfur addresses sulfur deficiency — increasingly common in modern soils. Sulfur is essential for protein formation, chlorophyll, and crop flavor development.

Common Questions