Effect of added magnesium, potassium, lime and nitrogen on oats: I. Yields

Abstract

With peat as the growth base the effect of the various combinations of three amounts of magnesium, of three of potassium, of two of lime and two of nitrogen on the grain and the straw crop yields, grown in pots, was investigated.During three seasons the magnesium fertilization did not affect the grain or the straw yield, the weight of the grain, or the rate of maturing in the first year. After the magnesium reserve had been exhausted the annual magnesium fertilization was needed to satisfy the requirements of an abundant crop. The highest level of potassium application together with a double magnesium fertilization rate caused a slight decrease in the yield, as the amount of water soluble salts in the growth base reached a high value. A deficiency in magnesium impeded more strongly the development of the grain crop than that of the straw crop; the maturing of the crop was delayed, and the grains were small. The ratio of potassium to magnesium in the annually renewed fertilization, when both nutrients were being used, did not affect the yield of oats. The amount of nutrients used had a more important significance than the ratio of the nutrients. Increase in the amounts of potassium, lime or nitrogen each had a diminishing effect on the yield if the plants were suffering from a deficiency of magnesium. Together with magnesium these treatments increased both the grain and the straw yields. Without the magnesium fertilization the highest rate of potassium increased clearly the value of the ratio K/Mg in the growth base, and caused a decrease in the yield.

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

“…The magnesium treatments caused more readily a change in the magnesium content than in the crop yield. Only a very low magnesium content in the growth base limited the yield (Jokinen 1977). In several experiments (Vigerust 1966, Birch et al 1966, Sorteberg 1975) the conclusion has been reached that magnesium fertilization does not affect the yield of cereals, but increases the magnesium content of the plants.…”

“…As the growth base in 5 liters Mitscherlich-pots was used 250 g of air-dry Sphagnum-peat 4.2). A more detailed description of the experiment has been presented previously (Jokinen 1977).…”