Using hydrophilic polymers to improve uptake of manganese fertilizers by soybeans

Abstract

Manganese deficiency in soybeans (Glycine max (L.) Merr.) is a common problem in many parts of the world. Recent research has demonstrated that the addition of gel-forming hydrophilic polymers with plant nutrients may enhance the availability and effectiveness of some soil-applied nutrients. This greenhouse study was designed to determine if the addition of hydrated cross-linked polyacrylamide polymers could increase plant recovery of commonly used Mn fertilizers by soybeans. Four Mn sources (MnO, MnSO₄·4H₂O, MnCl₂, and MnEDTA) were band applied at two concentrations to a low-Mn soil with and without one of two polymers. Addition of either polymer alone or MnO had no effect on leaf or stem Mn concentration, but when MnSO₄·4H₂O, MnCl₂, or MnEDTA were added with a polymer, leaf Mn accumulation swere increased an average of 89%, compared with those Mn sources applied alone. Plant accumulation of Mn from MnO was no greater than the control treatment and uptake was not increased following the addition of polymer. At the conclusion of the experiment, the polymers were still hydrated and the fertilizer band contained an abundance of roots. The use of a hydrophilic polymer with soluble Mn fertilizers appears to enhance the recovery by plants and may lead to lower Mn application rates or perhaps less frequent applications.