On the contents of moving magnesium and the ratio of potassium and magnesium in field soils of Estonia.
Due to the source rocks, Estonian soils are very heterogeneous by their contents of chemical elements. The methodologies used to identify fertilisation needs influence the objectivity of the results of contents of acquired nutritional elements and their ratio.
The research compared the moving magnesium contents identified b), ammonium lactate (AL) methodology and by IN KCl- 0,025N CaCl2-extraction. The results show that the magnesium contents in soils identified by the IN KCI and 0,025N CaCl2 extraction (Schachtschabel methodology) differ to a relatively small extent. Whereas the difference between the latter two and AL methodology is great (Figure 1). The difference is greater in case of soils that have high contents of calcium and specifically so in case Schachtschabel methodology is being used (Figure 2). In case of soils rich in calcium, some soils identified bv the AL methodology are rich in magnesium but poor as identified by 0,025N CaCl2 extraction methodology and there is no plausible relation between the results of research. The plausible linear connection between magnesium contents between magnesium contents identified by two methodologies appears in soils that contain moving calcium up to 2500 mg/kg (Figure 3). Therefore, the contents of magnesium identified by the AL and Schachtschabel methodology are only partly comparable since none of the methodologies have been worked out for soils rich in calcium.
When identifying the ratio of antagonistic nutrients that plants need, it is necessary to consider the identification methodologies because of great differences between them. In identifying magnesium by the AL methodology, the ratio of magnesium and potassium in soils (potassium was identified by the double lactate methodology (DL) is 0,5...0,6:1, but when identified from IN KCI and 0,025N CaCl2 extraction, the ratio is 2: 1. Thus, due to the differences in identifying methodologies, it is not possible to compare the ratio of contents of magnesium and potassium in the case of other methodologies