IN this week’s column, the National Agriculture Research and Extension Institute (NAREI) will provide some tips when it comes to fertilizing plants and the methods of fertilizer application.

When fertilizers are applied, care must be taken to ensure that the fertilizer is placed near enough for the roots to readily absorb it while at the same time the concentration is not so high enough to cause injury to the roots.

The soluble constituents of fertilizers diffuse through the soil vertically and only slightly in a lateral direction. The method of application, therefore, must ensure distribution to reach the plant roots. There are three methods generally used for fertilizer application. These are broadcast, placement and foliar application.

Broadcast
In this method, the fertilizer is spread as uniformly over the field as possible. This is commonly referred to as “shying.” This method is suitable for crops whose seeds are broadcast. The fertilizer is usually broadcast after the land has been ploughed and then mixed with the soil ploughs or cultivator.

Placement
Placement is when the fertilizer is put in a small area close to the plant or seed. This could be done in spots or as bands.

For the spot placement, the fertilizer is put approximately two inches away from the seed and five centimetres below the soil. The fertilizer should not be left exposed on the surface of the soils. This will lead to the loss of fertilizer. This method is useful for crops such as corn, pumpkin, squash, melons and cucumber which have large seeds.

In band placement, the fertilizer is placed in and on one side or both sides of the row, about five centimetres below the seed and five centimetres away from the seed or plant. This method is useful for crops which are sensitive to direct contact with fertilizer.
Band placement is also used for tree crops such as citrus, coconuts, avocado and papaws. In this case, the fertilizer is put in a circular band around the tree. Trees are usually treated individually, the fertilizer being applied around each tree within the spread of the branches, but beginning a few metres from the trunk.

Generally, the fertilizer is placed around the drip line of the plant canopy. The fertilizer must be worked into the soil as much as possible after application.

Foliar application
This is the application of fertilizer directly to the foliage of the plant as a liquid spray. The nutrients can be absorbed directly by plant leaves although only in limited quantities.