Response of sugar beet to foliar magnesium fertilization with epsom salt

Response of sugar beet to Epsom salt (MgSO4.7 H2O) foliar fertilization (ESFF) was tested in field trials on three locations during three growing seasons. Magnesium sulphate was applied as 5% w/v solution, 400 L/ha (two spraying in ten-day interval in June). In general, significant differences of sucrose concentrations, yields (root and technologic sugar), as well as K, Na and amino-N status in sugar beet root were found among years (influences of factor growing season) and among three tested localities (influences of factor soil characteristics) in all three years of testing. Also, the application of ESFF increased sucrose concentration by 0.25, 0.20 and 0.26%, at growing seasons 1995, 1996 and 1997, respectively. However, sugar yield was significantly increased in amount of 0.40 t/ha only in the third year of testing. Also, an improvement of root quality concerning in a decrease of amino-N content was found only in the second year of testing. ESFF was especially effective in increasing sugar concentrations under soil conditions showing moderate Mg supplies. The growing season 1997 was especially favorable for sugar beet growing. Under these conditions, ESFF significantly influenced on digestion (15.18 and 15.44%, for control and ESFF, respectively), sugar beet root yields (55.16 and 57.38 t/ha, respectively), sugar yields (7.12 and 7.52 t/ha, respectively) and root K contents (3.83 and 3.95 mmol/100 g of root, respectively). However, sodium (Na) and amino-N contents were not affected by ESFF treatment. Drought stress in 1995 was in close connection with the lower sucrose contents (12.38%) in comparison with the 1996 (15.10%) and 1997 (15.31%) growing seasons. Based on our three-year investigations, we would recommend foliar application of Epsom salt for sugar beet as usual crop management practice, especially under conditions of moderate soil-Mg and/or S supply.