Nitrogen and potassium fertilization and environmental factors affecting the grass tetany hazard of wheat forage

Abstract

The effects of temperature and soil moisture levels on the chemical composition of wheat forage grown in growth chambers were studied. In addition to the environmental variables, K and N fertilization effects were studied. In all the studies, increasing levels of K fertilization depressed the Mg and Ca concentration of the shoots. Nitrogen fertilization increased the Mg concentration but had no effect on the Ca concentration of the plants. N fertilization depressed the K concentration in the soil moisture experiment, but had no effect on K concentration in the temperature experiment. Increasing the temperature from 10 to 20°C did not affect the Mg and Ca concentration of the shoots, but the K concentration declined due to dilution effects caused by the greater yield at the higher temperature. In the soil moisture level experiment the K, Mg and Ca concentration in wheat tended to decline with soil moisture level due to dilution effects. Calculations showed that uptake of K was regulated primarily by diffusion of K from the soil to the plant root and that the uptake of Mg was regulated by the uptake process of the plant root and not by the nutrient transport process through the soil.