The effect of K and Na supply on sugar beet quality

The offspring of sugar beet, Beta maritima, has its normal growing place at the second seaweed sand bank on the beach. This environment has a high concentration of salt, NaCl. Opposite Danish soils, in beet growing areas, have very little or no content of sodium due to leaching during autumn and winter. For this reason, several investigations were carried out in 1988-1990 (6 trials). The goal was to determine the effect of sodium versus potassium and the optimal balance between supplied quantities of both. The investigation scheme covered supply of K 0, 50, 100 and 200 kg per ha and of Na 0, 50, 100 and 200 kg per ha (pure K and Na, not K2O). The comparisons go over the range from 0 K + 0 Na to 200 kg K + 200 kg Na totalling 16 combinations. Besides the normal yield assessments and purity analyses, also analyses of betain and invert sugar were carried out. The results showed a general sugar yield increase of 3 per cent and a rise in sugar content of 0. 17 per cent points for application of the combination of 100 K + 100 Na per ha. In the same combination juice content of amino-N, NH2N was reduced with 10.0 per cent. Some part of the juice content of amino-N became simply converted into betain, which increased to 6 per cent. Finally the juice content of invert sugar dropped with the same 10.0 per cent as for amino-N. The investigation proved sodium to be an essential nutrient and best in combination with potassium. The equivalent quantity of potassium alone (200 K), did not show the same beneficial effect as the combination 100 K + 100 Na. Later investigations have shown 100 K + 60 Na to be optimum and today this advice is followed by more than 80 per cent of Danish beet growers. The research work on sodium and potassium has increased the farmers sugar yield and economy and have finally improved the sugar recovery, and thereby the economy at the factories.