Extension Ag Update
December 2008
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On-farm Cooperators needed for Sulfur Soil Fertility Study

Fabian Fernandez, Extension Specialist, 217-333-4426, fernande@illinois.edu
Volunteers are needed throughout Illinois to participate in on-farm research measuring corn response to sulfur applications. While sulfur deficiency is not widespread, its frequency in corn has increased since it was first seen in Illinois three decades ago. This increase is likely the result of several factors, including less use of sulfur-containing fertilizers, insecticides, and fungicides; less atmospheric sulfur deposition; higher removal rates by increasing grain yields; increased use of conservation tillage, which may reduce sulfur availability; and fewer livestock operations, causing less application of manure.

Required soil conditions. In an effort to characterize sulfur response across the state, the study will be conducted in as many locations as possible under high-yielding environments. While soils with fine texture and high organic matter will be included, priority will be given to sites with low organic matter (less than 2%), coarse (sandy) texture, or both. These criteria were selected because they influence the natural sulfur-supplying power of the soil and the ability to retain sulfur in the rooting zone. Sites with suspect sulfur deficiency are particularly desirable. Fields that have received manure or sulfur applications in the last 5 years will not be considered.

Required equipment and sulfur sources. Volunteers will broadcast sulfur in strips using GPS to georeference the strip locations. Grain yields will be calculated using a yield monitor or weigh wagon.

Sulfur sources will be limited to ammonium sulfate (NH4)2SO4 (21-0-0-24); MicroEssentials sulfur (ME S), ME S15 (13-33-0-15) or ME S10 (12-40-0-10); and elemental sulfur (0-0-0-90). One or two sulfur rates will be applied in strips; each will be replicated at least three times. If the sulfur source contains other accompanying nutrients, the corresponding rates will need to be applied to other treatment strips to avoid a differential response to nutrients other than sulfur.

Volunteers will not be required to take plant or soil samples, but they need to allow the researcher to visit the strips approximately three times during the growing season.

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