Application method will affect the accessibility of applied nutrients. Different placement methods can ensure that the nutrient is immediately available to rapidly growing plants (e.g. banded below the seed at planting) or is applied very gradually over a lengthy growing period (e.g. fertigation in horticulture). Placement will also affect the degree of interaction between the fertiliser and the soil, which is particularly important where nutrients can become unavailable due to reactions with soil minerals (e.g. phosphorus fixation) or organic matter (e.g. nitrogen immobilisation).
Placement of fertiliser should conform to the Spreadmark Code of Practice for both Aerial and Ground Fertiliser Spreading.
Common options for fertiliser placement include:
- surface broadcast application (by ground or aerial spreading)
- surface broadcast and incorporated
- banded into the soil at various band widths and depths
- surface banded
- foliar application
- fine particle suspension or slurry application (ground or aerial).
The best placement method will depend on the nutrient(s) concerned, topography and individual production situations. For example, applications to crops, especially in horticulture, generally require more accuracy and precision than applications to intensive pastures where nutrients are continually redistributed by the grazing animals.
In deciding on the right application method, key questions to consider include:
- does the method apply the nutrient sufficiently accurately for its purpose?
- is the equipment suitable for the terrain and soil conditions?
- is the equipment appropriate for the size of the application area?
- is the use of the equipment likely to result in noise or dust nuisance to third parties?
- is the equipment certified to meet accuracy requirements?
There is more detail about application methods and best management practices for fertiliser spreading in Fertiliser Application