Florida tomato farmers may increase their yields by adding sulfur to their soil before planting, according to a University of Florida study published in the current issue of the journal HortTechnology.

Adding 25 pounds of elemental sulfur per acre boosted yields by 1.7 tons per acre in the study, said Bielinski Santos, an associate professor with UF’s Institute of Food and Agricultural Sciences and part of the research team responsible for the paper.

Sulfur is an important major nutrient and one of the ways it reaches agricultural fields is via atmospheric deposition. However, in recent years the amount of sulfur in the atmosphere has declined, due to tougher clean-air standards. So some farmland may not have the same sulfur content it once did.

“Growers should be aware that sulfur-related deficiencies are now more common than a few years ago in vegetables and small fruit crops,” said Santos, who is based at UF’s Gulf Coast Research and Education Center in Balm.

There are no field tests available for soil sulfur content, Santos said. So he recommends adding a sulfur amendment to soil once each year.

In the study, scientists grew tomatoes on sandy soil at the Balm center.

Treatments were set up using sulfur amendments ranging from 25 pounds to 200 pounds per acre. The results showed that soil amended with 25 pounds per acre yielded 1.7 tons more marketable fruit per acre, compared to a control plot with no sulfur amendment.

Adding more sulfur had little additional benefit, Santos said. The 25 pounds per acre falls within UF/IFAS recommendations for Florida vegetable production.

Santos said that possible sulfur sources include gypsum, elemental sulfur and sulfate-based fertilizer.

He added that a UF/IFAS research team has conducted similar experiments with strawberries and found similar results. That study will be published in the coming months.