The effect of movable magnesium content and Ca:Mg ratio on field crops

The aim the research work was to find out the ratio of mobile Ca and Mg in the arable layer of soils and the dependence of the ratio on fertilization. Also the importance of Ca-, Mg- and K- ratio for plants development and in case of Mg-fertilization was studied. The trials were conducted on soddy-podzolic and soddy-calcareuos soils, where red clover and annual ryegrass were grown. The ratio of mobile Ca and Mg in the arable layer varies a great deal: from 6 to 50. As Mg has a better mobility in soil than Ca, it is also more easily leached out. The result is that in soddy-calcareuos soils where no Mg-fertilizers are used, Ca:Mg ratio constantly widens. In soddy-podzolic soils where Ca content is low, the ratio Ca:Mg is often so narrow that inspite of Mg shortage in soil, the fertilization with Mg turnes out to be useless. Neither too wide, nor too narrow Ca:Mg ratio is good for the take-up of nutrients by plants. For red clover the most suitable ratio was between 10...19. Important are also the ratios Ca:K and K:MG, which affect particulary the assimilation of K, Ca and Mg