About the effect of the contents and ratios of soil’s available calcium, potassium and magnesium in liming of acid soils
Agricultural Research Centre, Teaduse 4/6, 75501 Saku, Estonia; e-mail: email@example.com
Soils in Estonia are characterised by washing out, i.e. leaching, of calcium carbonates and magnesium carbonates. Calcium losses from the arable layer may amount 150–500 (600) kg ha-1 a year, resulting in excessive concentration of free hydrogen ions in the soil solution, and therefore these soils require liming. Relatively high doses of lime fertilisers have to be used in order to eliminate harmful acidity of the soils. Clinker dust, oil shale ash and milled limestone are the materials widely used as lime fertilisers at present. Soils in Estonia are often poor in both potassium and magnesium, and that is why clinker dust, which is relatively rich in potassium, has been a particularly valued lime fertiliser. Magnesium deficiency is being alleviated by adding dolomite meal to milled limestone. However, a non-uniform mixing of these lime fertilisers does not ensure their sufficiently homogeneous consistence. Large doses of lime fertilisers, which are not uniformly mixed, have a variable effect on the contents and ratios of calcium, potassium and magnesium in the soil. The trials showed that, as a result of an incorrect use of lime fertilisers, both calcium-to-magnesium and potassium-to-magnesium ratios in the soil may change to the detriment of plants, leading to lower yields.