Effects of nitrogen fertilizer, plant population and irrigation on sugar beet: II. Nutrient concentration and uptake

Abstract

SUMMARY: The concentration of nitrogen, phosphorus, potassium, sodium, calcium and magnesium was measured in the dry matter of sugar beet from four field experiments (1966–9). All combinations of four amounts of nitrogen fertilizer (0–1·8 cwt/acre), four plant populations (8800–54000 plants/acre) and irrigation were tested, which gave a wide range of plant size and yield. Nutrient concentration and uptake by the crop were also greatly affected by the treatments.Nitrogen fertilizer and irrigation increased uptake of nitrogen by the crop but increasing the plant population had little effect on uptake and decreased the concentration of nitrogen. Sugar yield was related to the total nitrogen concentration in tops and roots and to uptake. There were optimal values of nitrogen concentration for maximal sugar yield, but the optima were greatly affected by plant population. Leaf colour was a good guide to nitrogen concentration.Phosphorus concentration was affected little by the treatments but cation concentrations were greatly affected. In general, uptake of all the elements was increased by all treatments – the exception was sodium, which decreased as the plant population increased but this was balanced to somo extent by increased potassium uptake.