Top dressing fertilizer for maize works best when it is applied at the correct crop growth stage at the recommended rate. This article explains why.
For maize, urea application timing depends on an understanding of the growth stages. As many crops reach to dressing timing, we look at the main requirements of the crop. Nitrogen applied at the 3-4 leafs stage with a broadcaster leaves nitrogen vulnerable to leaching when the crop does not require it.
Nitrogen and other nutrients are not taken up at a constant rate through the crop life. Applying at 3-4 leaf stages leaves probably a 4-6 weeks gap before the crop is really taking up fertilizer. Even slow release top dressing fertilizer for maize do not overcome this in trials that have involved with. This is especially true in areas with over 600mm of rainfall like we are experiencing now.
In recent years there have been a trend among maize growers to apply Calcium Ammonium Nitrate (CAN) fertilizer to their crops in preference to urea. The lower volatilization risk on dry soils and the perceived neutral effects on soil acidity has encourage the trend, along with the subsidized price through the National Cereal Produce Board.