Extension program on prevention/correction of manganese (Mn) deficiency in soybean;
Joseph Hickman ( Rutgers University) ($2000). The Project Manager's email is firstname.lastname@example.org.
Key Words: Manganese (Mn)
Manganese (Mn) deficiency is a recurring problem in many crops grown on Atlantic Coastal Plain soils, especially soybean. An experimental site near Adephia, NJ has a long history of crops exhibiting manganese deficiency. This sandy loam soil had an initial soil pH of 7.5, Mehlich-3 extractable Mn of 12 mg per kg, and soil organic matter content of 2.3%. A Roundup Ready® Soybean variety was used to study crop response to Mn fertilizer treatments as glyphosate has been suspected of increasing the severity of manganese deficiency. The first trial compared manganese sulfate to chelated manganese as foliar fertilizer applications. Crop response showed increased seed yield with application of Mn fertilizer, but no significant differences were exhibited between the two Mn fertilizer sources. The second trial compared different rates (0, 0.5, 1.0, 1.5, and 2.0 lbs Mn acre-1) and frequencies (none, once-at emergence of first trifoliate, twice-at first trifoliate and at early bloom, or three times-at first trifoliate, early bloom, and early pod fill) of foliar applied manganese fertilizer as manganese sulfate. As expected, during both trials, plants without foliar Mn fertilizer treatment exhibited severe Mn deficiency showing classic symptoms of interveinal chlorosis or leaf yellowing. During the second trial, a minimum of three foliar applications of Mn were required to achieve yield potential. However, there was no advantage to using application rates greater than 0.5 lbs Mn acre-1. On field sites severely deficient in Mn, effective correction of Mn deficiency requires frequent, but low, application rates of foliar Mn fertilizer. Manganese sulfate and chelated manganese fertilizers appear to reduce deficiency symptoms and increase yields of Roundup Ready® soybean grown on Mn deficient soils similarly.
This project is funded by New Jersey Soybean Board