A pot experiment was carried out in a greenhouse to investigate the influence of the percentage of Ca, Mg, K and H occupying the soil’s cation exchange capacity (CEC) on the yield of annual ryegrass. The experiment comprised 13 fertilization treatments with various basic cation saturation ratios in soil. The experimental design consisted of three parts. In part A, the soil’s saturation level of Ca was increased (from 41% to 71%), in part B, the saturation level of Mg was elevated relative to the remaining cations (from 5% to 33%), and in part C, the saturation level of K was raised (from 2% to 11%). The results of this study indicate that high yields of annual ryegrass with balanced mineral composition can be achieved when 50–60% of the exchange complex is occupied by Ca, 8-12% by Mg and 4-5% by K. A rise in K saturation above 5% increased ryegrass yield, but it also led to deterioration in the quality of green forage due to excessive accumulation of K and lower concentrations of Mg and Ca in grass. A significant decrease in the yield of annual ryegrass was noted when the soil’s base saturation level of K dropped below 4%. The increase in the soil’s saturation level of Mg from 5% to 12% contributed to an increase in the weight of annual ryegrass plants. Despite the absence of significant differences in yield between treatments, the increase in Mg saturation from 5% to 12% was fully justified because it improved the quality of green forage. The soil’s saturation levels of all major cations is an important indicator of soil productivity.

23.1.2018