By George Silva, Michigan State University Extension
Recent research publications have highlighted potential sulfur (S) deficiencies in corn and soybeans in the North Central region. Sulfur is not mobile within the plant, so symptoms usually appear in the new growth. Atmospheric deposition used to supply a considerable amount of plant available S (about 8 to 15 lbs./A annually), but with the implementation of the Clean Air Act, this amount has significantly decreased. Another important source of S is the soil organic matter. When organic matter decomposes, S is released as a sulfate ion into the soil solution. In Michigan, sulfur deficiencies are most likely to occur on coarse-textured soils with low organic matter. Other factors that may contribute to the need for supplemental S include increased crop removal rates in intensive cropping systems and lack of S impurities in major fertilizer sources.
In 2012, an on-farm research project was conducted in Perry, where two liquid starter fertilizer products, eNhance and Access containing S, were applied at the rate of 2 quarts/A in 2X2 band and compared with untreated (Table 1). The treatment strips were randomized and replicated four times. In addition to S, these two products also contained some micronutrients. The soil characteristics were pH = 6.3, Cation Exchange Capacity (CEC) = 5.1 meq/100g and soil organic matter = 1.7%.
Although statistically significant, the yield differences between the three treatments were less than two bushels. Access®, which has the highest S content, produced the highest soybean yield, but eNhance® produced no yield response. The S sufficiency range for soybeans is between 0.20 to 0.50 percent. All three treatments in our study were within this range. Drought conditions in 2012 may have contributed to reduced nutrient uptake in 2012. Despite this field being a mineral soil with low CEC and low organic matter, the expected increases in soybean yield and sulfur uptake from supplemental S were not evident. However, this data represents only one site and one year.
Additional information on nutrient sufficiency ranges is found in the Michigan State University ExtensionBulletin E-486, Secondary and micronutrients for vegetables and field crops.
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