Abstract
Manganese (Mn) is an essential micronutrient for all organisms. In plants, Mn plays a critical role in photosynthesis and as a structural component of enzymes. In soils, Mn exists as different fractions of varying availability to plants. Mn fertilizers can be used to increase Mn availability to plants but are easily converted from a plant-available fraction (exchangeable Mn) to an unavailable fraction (Mn-oxides). Little research has been done in agricultural settings on soil Mn fractions; thus, the objective of this experiment was to study the effect of Mn additions on soil Mn fractions and plant Mn concentration. A greenhouse experiment was conducted by growing soybean (Glycine max) treated with three Mn application rates (recommended or 1×, 10×, and 50×) of two sources (MnSO4 and Mn ethylenediamine tetraacetic acid [MnEDTA]). Soil Mn fractions (Mehlich-1 extractable, exchangeable, organic-bound, Mn-oxide, residual) were quantified via sequential Mn extraction procedures. Bioavailability was evaluated by measuring soybean leaf Mn concentrations. Both fertilizer types increased available soil Mn fractions. Leaf Mn concentration increased with MnSO4 50× application at the V3 stage and decreased with MnEDTA addition at the V3 and R2 stages. Mn additions likely resulted in the conversion of Mn into unavailable fractions. This was amplified by higher application rates, where total Mn increased by 18.5%, but available Mn decreased by 4.3% relative to initial soil values. Thus, our study showed that adding Mn to soils does not necessarily increase plant-available Mn.
| Original language | English |
|---|---|
| Pages (from-to) | 1120-1135 |
| Number of pages | 16 |
| Journal | Soil Science Society of America Journal |
| Volume | 87 |
| Issue number | 5 |
| DOIs | |
| State | Published - Sep 1 2023 |
Funding
This research was funded by the Laboratory Directed Research and Development program of Oak Ridge National Laboratory (ORNL) managed by UT-Battelle, LCC for the U.S. Department of Energy under contract DE-AC05-00OR22725, and by the Critical Interfaces Science Focus Area project supported by the Office of Biological and Environmental Research in the DOE Office of Science. We thank Rachel Wooliver and Avishesh Neupane for assistance with plant harvesting and sample collection, and Hui Li for conducting the ICP analysis. This research was funded by the Laboratory Directed Research and Development program of Oak Ridge National Laboratory (ORNL) managed by UT‐Battelle, LCC for the U.S. Department of Energy under contract DE‐AC05‐00OR22725, and by the Critical Interfaces Science Focus Area project supported by the Office of Biological and Environmental Research in the DOE Office of Science. We thank Rachel Wooliver and Avishesh Neupane for assistance with plant harvesting and sample collection, and Hui Li for conducting the ICP analysis.