Onions (mature and dry) (Code #172)
Soil Test RatingPotassium

Low K

Coast: 0-70 lbs/A

Pied: 0-120 lbs/A

Medium K

Coast: 71-170 lbs/A

Pied: 121-250 lbs/A

High K

Coast: 171-275 lbs/A

Pied: 251-400 lbs/A

Very High K

Coast: 275+ lbs/A

Pied: 400+ lbs/A

PhosphorusRecommended Pounds N-P205-K20 per Acre

Low P

Coast: 0-30 lbs/A

Pied: 0-20 lbs/A

*-120-120*-120-90*-120-60*-120-45

Medium P

Coast: 31-60 lbs/A

Pied: 21-40 lbs/A

*-90-120*-90-90*-90-60*-90-45

High P

Coast: 61-100 lbs/A

Pied: 41-75 lbs/A

*-60-120*-60-90*-60-60*-60-45

Very High P

Coast: 100+ lbs/A

Pied: 75+ lbs/A

*-45-120*-45-90*-45-60*-45-45

Coast = Coastal Plain    Pied = Piedmont, Mountain, and Limestone Valley

Recommendations:

Recommended pH:6.0 to 6.5. If the pH is less than 6.0, see Lime Table B.
Nitrogen:Coastal Plain 125-150 pounds nitrogen (N) per acre.

Piedmont, Mountain, Limestone Valley 110-130 pounds nitrogen (N) per acre.

Magnesium:

If soil test Mg level is low and lime is recommended, use dolomitic limestone; if soil test Mg is low and lime is not recommended, apply 25 pounds of Mg/Acre.

Coastal PlainLow: 0 - 60 lbs/acre Medium: 61 - 120 lbs/acre High: >120 lbs/acre
Piedmont Low: 0 - 120 lbs/acre Medium: 121 - 240 lbs/acre High: >240 lbs/acre
Zinc:If the Zn soil test level is low, apply 5 pounds of zinc per acre.
Sulfur:See Fact Sheet
Boron:Apply 1 pound of boron (B) per acre.

Fact Sheet:

Nitrogen (N) rates will vary depending on rainfall, soil type, irrigation, plant population and method and timing of applications. Avoid high nitrogen applications until after danger of excessive cold weather. Apply the last nitrogen applications at least 4 weeks prior to harvest.

For early growth stimulation apply a pop-up fertilizer using 100 to 150 pounds of 10-34-0 or similar material per acre. Apply the fertilizer 2 to 3 inches to the side of the seeds or plants and 2 to 3 inches below the seeds or roots.

For more efficient use of fertilizer split the applications, applying one-third to one-half down (banded or incorporated in the bed) and the remainder in 1 to 3 applications. If the fertilizer is broadcast, increase the application rates of phosphate (P2O5) and potash (K2O) 1½ to 2 times.

Apply 40 to 60 pounds sulfur per acre. On sandy soils applications should be split with the last application being made prior to the end of January. Applications later than this may increase pungency.