Field study will examine soybean response to sulfur

Reduced atmospheric deposition, higher crop removal rate, slower organic matter turnover and unreliable soil test are contributing to the need to investigate supplemental sulfur requirements of field crops.

Soybean response to supplemental sulfur (S) is the topic of a field investigation in Perry, Mich., in 2013.
An on-farm research project is being conducted where a liquid starter fertilizer Access containing 17 percent S was applied to soybeans. The recommended rate was 2 quarts/A band applied 2X2 inches at planting. This will place about a pound of S per acre in a band close to the seed. Plots were 30 feet wide (12 rows) and 1,553 feet long and the treated plots are being compared with untreated plots side by side. Treatments were randomized and replicated five times. The soil was a Boyer sandy loam with low organic matter. The soybean variety was Syngenta 29-V2, a 2.6 maturity group Roundup Ready variety with Avicta and Vibrance seed treatments.

Recent research has suggested potential S deficiencies in corn and soybeans in the north central region. Atmospheric deposition of S has considerably decreased following the Clean Air Act. Organic matter is an important source of S and when it decomposes, S is released as a sulfate ion into the soil solution. Michigan State University Extension recommendations suggest that sulfur deficiencies are most likely to occur on coarse-textured soils with low organic matter. Sulfur is not mobile within the plant, so deficiency symptoms appear in the new growth (early season general chlorosis). Plants sometimes grow out of this condition as roots expand and penetrate the soil.

During the season, sulfur and other micronutrient uptake of soybeans will be monitored by analyzing the first trifoliate leaf tissue. Soil testing for S is not as reliable as tissue analysis. Please refer to the MSU Extension bulletin E-486, “Secondary and micronutrients for vegetable and field crops,” for S sufficiency range on soybeans. The most important aspect of this trial is to ascertain if the addition of sulfur would result in a consistent yield increase on coarse-textured soils.

This study was funded by the Michigan Soybean Promotion Committee. I would like to thank Mike Staton, senior MSU Extension educator; Will Willson, soybean producer from Perry, Mich.; and Brian Martindale, Agro-Culture liquid fertilizer dealer from St. Johns, Mich., for their collaboration in this study.

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