In Summary
  • Urea or CAN as a source of nitrogen boost for maize works best when it is applied at the correct crop growth stage and at the rate advised by the supplier (which usually is a spoonful per plant when done manually).
  • Nitrogen and other nutrients are not taken up at a constant rate through the crop’s life. Many farmers apply fertiliser at around the three to four leaf stage, which is too early for the nitrogen requirement of the plant, so the knee-high or six to eight weeks post-emergence is the appropriate timing for the nitrogen boost for maize.
  • Whilst embracing good farming practice, it is also best to weed before they flower so that they can’t seed, which would see them regrow.

Farmers continue to record low maize yields of between nine to 11 bags per acre against a target of 30 to 40 bags in most regions. This is partially blamed on poor farming practices.

Top-dressing is the application of nitrogen in granular fertiliser form to crops to boost the nitrogen available to the plant as it is growing.

Top-dressing and weeding go together because the removal of unwanted competitive plants is very important so that the fertiliser granules that boost the nitrogen, which should be placed at the base of the plant, are not taken up by the competing weeds, which would limit yields during times of high nitrogen demand from the maize plants.

Urea or CAN as a source of nitrogen boost for maize works best when it is applied at the correct crop growth stage and at the rate advised by the supplier (which usually is a spoonful per plant when done manually).

Ideally, this should be done when the maize is knee-high (about 18 inches tall), which means the plant’s root ball will have grown to around nine inches of depth under the soil.

Urea is the cheapest form of nitrogen but should only be used when rain is guaranteed so that the granules are dissolved and absorbed by the soil in 24-48 hours.

Beyond this, urea will hydrolyse and will be lost as gasses to the atmosphere. If rain is uncertain, CAN, whilst more expensive, is by far the better option.

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