Effects of potassium, sodium and chloride fertiliser rates on fodder beet yield and quality in Canterbury

Abstract

There is renewed interest in fodder beet (Beta vulgaris L.) production in the South Island of New Zealand. However, recommended agronomic practices for maximising productivity and quality are limited. Two experiments investigating the effects of different rates (kg/ha) of potassium (K; 150 or 300), sodium (Na; 100 or 200) and chloride (Cl; 240) fertiliser application on fodder beet dry matter (DM) production, nutrient concentration and uptake were carried out at Southbridge (2011) and Bankside (2012), Canterbury, New Zealand. Final DM yield was unaffected by the treatments: averaging 32 t DM/ha at Southbridge and 21 t DM/ha at Bankside. However, there was a significant interaction between K and both Cl and Na, on DM yield at Southbridge. Specifically, yield increased to 38 t DM/ha with Na and decreased to 30 t DM/ha with Cl, in the presence of K. Application of K, Na, and Cl fertiliser increased the respective tissue mineral concentration and respective total uptake for both the bulb and shoot components. Potassium tended to depress crude protein, neutral detergent fibre and ash content of the bulbs and increase the metabolisable energy and soluble sugar. The combination of low fibre and high soluble sugar concentrations puts animals at risk of rumen acidosis. These results suggest that fodder beet crops subjected to high rate of soil and/ or fertiliser K should be supplemented with feed high in crude protein and fibre. Key words: Beta vulgaris L., agronomic practices, mineral concentration, mineral uptake, quality attributes.