Ideal pH: 6.0-6.8. Humus-rich, deeply cultivated soil is key. Add plenty of well rotted compost or manure to th ebeds and cultivate to a depth of 20cm (8"). Dig in 1 cup of complete organic fertilizer for every 3m (10') of row. The real secret to success with turnips is speed. Sow short rows every 2-3 weeks, thin them quickly, keep them watered, harvest, and then sow some more.