USING HYDROPHILIC POLYMERS TO IMPROVE UPTAKE OF MANGANESE FERTILIZERSBY SOYBEANS

Manganese deficiency in soybeans (Glycine max (L.) Merr.) is a common problem in many parts of the world. Recent research has demonstrated t hat the addition of gel-forming hydrophilic polymers with plant nutrie nts may enhance the availability and effectiveness of some soil-applie d nutrients. This greenhouse study was designed to determine if the ad dition of hydrated cross-linked polyacrylamide polymers could increase plant recovery of commonly used Mn fertilizers by soybeans. Pour Mn s ources (MnO, MnSO4 . 4H(2)O, MnCl2, and MnEDTA) were band applied at t wo concentrations to a low-Mn soil with and without one of two polymer s. Addition of either polymer alone or MnO had no effect on leaf or st em Mn concentration, but when MnSO4 . 4H(2)O, MnCl2, or MnEDTA were ad ded 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 w as 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 polyme r with soluble Mn fertilizers appears to enhance the recovery by plant s and may lead to lower Mn application rates or perhaps less frequent applications.