Gordon Johnson, Extension Vegetable & Fruit Specialist; firstname.lastname@example.org
Vegetable growers should note that sulfur (S) recommendations have been added to the 2022-23 Mid-Atlantic Commercial Vegetable Production Recommendations in the footnotes of the Recommended Nutrients section for each crop. For example, in the cole crop chapter below, 25-40 lbs. of sulfur are recommended.
Sulfur is one of the secondary macronutrients that vegetable crops require for growth. Sulfur is a component of four amino acids and is therefore critical for protein formation. It is also a component of certain glycosides that give pungency to mustard family crops (greens, cole crops) and allium crops (onions, garlic).
In the last 30 years, as industrial air pollution has been reduced (especially pollution from coal fired power plants) we have had less sulfur deposition from rainfall. Sulfur deficiencies are common and sulfur additions from fertilizer or manure are required for all vegetable crops to produce high yields.
Most of the sulfur in the upper part of the soil is held in organic matter. Upon mineralization, sulfur is found in the soil as the sulfate ion (SO42) which has two negative charges. The sulfate ion is subject to leaching, especially in sandy textured soils (loamy sands, sandy loams). It does accumulate in the subsoil but may not be available for shallow rooted vegetables.
In vegetable crops, sulfur removal is generally in the 10-25 lb/A range. Mustard family crops (cole crops such as cabbage and broccoli, mustard and turnip greens, radishes) remove between 30 and 45 lbs/A of sulfur. Research in our region has shown response to added sulfur for sweet corn and for watermelons. In Florida research it was shown that adding 25 pounds of sulfur per acre boosted yields by 1.7 tons per acre in tomatoes. Similar results were found with strawberries.
Our general recommendations are to apply 25-30 lbs of sulfur per acre for most vegetable crops. Remember to take credit for any sulfur being added with fertilizer sources such as ammonium sulfate (24% sulfur).
One vegetable where we want to limit sulfur is with sweet onions. Because sulfur increases onion pungency, and sweet onions are sold based on their low pungency, we limit sulfur applications to this crop.