Agriculture Reference
In-Depth Information
is a tendency to use an excess of nitrogen on most crops, which can lead to
excessive vegetative growth and environmental contamination, besides being
a waste of fertilizer and increasing production costs.
Timing of application
Nitrogen, if applied conventionally, should be applied three or four times a
year in equal amounts, with the fi rst application before fl owering or the main
growth fl ush. The next applications will follow at 3- or 4-month intervals.
If there is no irrigation, the fi rst application should be done as soon as the
rains start, and the other two or three divided so that the last is made 2 weeks
before the rains stop. Potassium can be split into two or three equal fractions
and applied with the second and third, and eventually the fourth, nitrogen
application, if nitrogen is applied four times a year. Magnesium can also be
split into two or three applications. Phosphorus, since it is readily immobilized
in the soil, can be applied all at once for the whole year, normally with the fi rst
application of nitrogen. Nitrogen should not be applied close to harvest, as this
results in fruits that are more succulent, mature later and are not as sweet and
tasty. Nitrogen is preferably applied right after harvest
Fertilizer application
Solid application
When low-volume or sprinkler irrigation systems are not installed, con-
ventional soil fertilizer application systems are used. This application of dry
fertilizers to the soil is made by broadcasting the fertilizer on to the soil surface
over the outer half or third to the canopy drip line. There is no need to apply
fertilizer near the tree trunks, as the old roots have little nutrient-absorption
ability. Small banana growers apply dry nitrogen and potassium fertilizer
four times a year, while phosphorus is normally applied once a year; these
applications are done by applying the fertilizer in a semicircle about 60 cm
long and 30 cm wide in front of the ratoon sucker, about 30 cm from its base.
When the plants are closely spaced, fertilizer can be broadcast uniformly
in the space between rows, as it is assumed that this area is fi lled with roots.
Alternatively, a shallow semicircular furrow about 40 cm long and 5 cm deep
is excavated with the edge of a hoe or square shovel 30-40 cm from the main
stem; the fertilizer is put in the furrow and covered. Sometimes fertilizers are
applied following the irrigation furrows or in the basins, which ideally should
be wet. Fertilizers such as urea should not be left exposed but covered with a
rake or irrigated into the soil to avoid volatilization of the active components.
The fertilizer should be applied when the soil is wet and moved from the
