Sulfur Fertilization Rarely Boosts Yield in Ohio Grain

Since the Clean Air Act amendment of 1990, atmospheric sulfur (S) deposition has been reduced by more than 80% in Ohio. As the main exogenous source of agricultural S has diminished, there is increasing concern that S availability could now be limiting crop yield. Today, application of S is more common throughout the state, but its benefits remain unclear. A handful of research trials reported grain yield response or other crop benefits, but the results remain inconsistent across soil type, S rate, and sources.

A team from Ohio State University conducted 96 replicated trials (50 corn, 34 soybean, and 12 wheat trials) at varying S rates and sources from 2013 to 2021. The researchers found very little evidence that S fertilization increases grain yield. In only four of the corn trials and three of the soybean trials did yield increase after S application. They also found that liquid S sources with high salt index occasionally reduced corn yield. In contrast to grain yield, S concentrations in the tissue and grain frequently increased with S fertilization.

The results suggest there is sufficient endogenous S to meet grain crop requirements; S application is rarely needed in Ohio soils to optimize crop production.