Comparison of the effect of the fertilization on arable crops, between two types of the magnesium fertilizer (lightly-burned magnesium and sarpomag)

In order to compare two types of the magnesium fertilizer (lightly-burned magnesium: including 650-800 g/kg of citric acid soluble MgO, sarpomag: including 185g/kg of water soluble MgO), a laboratory elution experiment and several field experiments of spring wheat, soybean, sugar beet and potato, were conducted. The laboratory elution experiment showed that the magnesium from sarpomag was quickly eluted in water while the magnesium in lightly-burned magnesium was never eluted in water, but slightly soluble in nitrate solution. And the elution of lightly-burned magnesium was in proportion with the concentration of nitrate solution. As seen above, the dissolubility of lightly-burned magnesium was considerably less than that of sarpomag. Comparison of the two magnesium fertilizers by the field experiments, applied to spring wheat, soybean, sugar beet and potato, showed that there was no significant difference between the two magnesium fertilizers in crop yields, crop quality, MgO concentration of the plant body, MgO uptake, at the harvest time. Moreover, in the case of spring wheat and sugar beet, there was no significant difference between the lightly-burned magnesium plot and the sarpomag plot, in the midway of the growing. However, in some cases of the midways of the growing of soybean and potato, MgO concentration of the leaf and MgO uptake in the lightly-burned magnesium plot were significantly lower than those in the sarpomag plot, especially the tendency was more explicit in soybean. Even so, both of lightly-burned magnesium and sarpomag could be thought as having no problem when being used as the ordinary magnesium fertilizer, because no magnesium deficiency was observed in any experimental plots of all the studied crops, and because the fertilization effects of the two magnesium fertilizers on soybean and potato in the harvest time were observed as no difference. On the other hand, the fact that exchangeable MgO of the soil after harvesting was significantly higher in the sarpomag plots than those in the lightly-burned magnesium plots, should be noticed carefully.