Characterization of Different Magnesium Fertilizers and Their Effect on Yield and Quality of Soybean and Pomelo

Abstract

Fertilizer application, especially their physical and chemical composition, substantially regulates crop growth and development. The form in which fertilizers are applied to the soil has always been regarded as a crucial factor regulating nutrient availability. However, the properties and release characteristics of Mg fertilizers, i.e., fast-release Mg (F-Mg) and slow-release Mg (S-Mg), have not been fully elucidated in acidic soils. This study characterized the different Mg fertilizers, and their release characteristics were verified through pot (using soybean) and field (using pomelo) experiments. The results showed that, despite the differences between different Mg fertilizers, the same functional group peaks were recorded among them. F-Mg fertilizers had a low pH and low Mg purity, while S-Mg fertilizers had a high pH and high Mg purity. The release rate and leaching characteristics of the F-Mg fertilizers were higher than the S-Mg fertilizers. The pot experiment showed that the yield and growth of soybean were higher under the S-Mg fertilizer than the F-Mg fertilizer. However, MgSO4·7H2O and MgO had the best effect among the F-Mg and S-Mg fertilizers, respectively. The effects of these two fertilizers were further validated using field experiments, and it was found that MgSO4·7H2O and MgO fertilizers substantially improved the yield and quality of pomelo. However, MgO showed a better effect than MgSO4·7H2O. This study can provide a sound theoretical basis for selecting the most efficient type of Mg fertilizer for acid soils. It can contribute valuable information regarding farmland management strategies and may result in sustainable agricultural productivity.