How much and when should I top dress nitrogen in maize for good cobs?

Maize is a heavy nitrogen feeder, so split the dose rather than applying it all at once: a common approach is some basal at sowing, a major top dressing at the knee-high or 6 to 8 leaf stage, and another around tasseling. Typical total nitrogen is roughly 100 to 120 kg per hectare or more for high yielding hybrids, but follow your soil health card and the hybrid recommendation. The knee-high stage top dressing is the most critical for cob size and grain filling, so do not miss it, and apply urea into moist soil and irrigate after, or place it near the row, to reduce loss. Also ensure enough phosphorus, potash and zinc, as zinc deficiency is common in maize. Confirm the exact split and dose with your local KVK.