Effect of added magnesium, potassium, lime and nitrogen on oats: II. Nutrient contents, cation ratios and magnesium uptake

Abstract

In a pot experiment on sphagnum peat soil the magnesium fertilization increased significantly the magnesium content of the grains and the straws of oats. The addition of potassium fertilization decreased the magnesium content when the plants received a magnesium fertilization. Without magnesium the rate of potassium fertilization did not have an effect on the magnesium content of the straws. The increase in the equivalent ratio of the three potassium rates and the two magnesium rates decreased the magnesium content of both the grains and the straws. Along with the magnesium fertilization the addition of lime decreased the magnesium content of the grains and increased that of the straws. Doubling the amount of the nitrogen fertilization with the magnesium fertilizer increased the magnesium content of the grains and the straws. In the case of magnesium deficiency the addition of lime or nitrogen did not have an effect on the magnesium content of the yields. The rate of magnesium, potassium, lime and nitrogen did not have an effect on the potassium content of the grains. The potassium content of the straws increased with the addition of potassium. Without the magnesium fertilization the potassium content, as well as, the ratios K/Mg and K/(Ca + Mg) in the grains and the straws were high. A part of the missing magnesium had, perhaps, been substituted for by potassium. The calcium content of the grains and the straws obtained without magnesium fertilization was significantly higher than the calcium content with magnesium fertilization. The oats substituted possibly in part also calcium for the missing magnesium. The effect of added magnesium, potassium, lime and nitrogen on the magnesium uptake by oats was discussed.