Figure 2. Effect of temperature on the longevity of controlled release fertilizers.
nus is that the CRF may even con-
recommended when using CFRs.
nous, resulting in differences be-
tinue to supply nutrients after the
Nutrient loss through leaching can
tween plants. One way this can be
consumer has bought the plant.
also therefore be considerably re-
overcome is to use a combination
duced when using CRFs and irriga-
of water soluble fertilizers and CRFs
tion is carefully monitored. Using
especially with heavy-feeding crops.
The release rate of CRFs will however not only be affected by the type
of coating but also by the substrate
CRFs can also be a lot simpler in
temperature and moisture content.
terms of the irrigation set-up and
Over-irrigation can lead to substantial losses and in contrast to the
recommended
15-20%
drainage
recommended for plants fertigated
with water soluble fertilizers no or a
very limited amount of leaching is
management, although monitoring
of the EC, pH and specific nutrients
in the root zone is necessary,
whether water soluble or CRFs are
used, to maximize plant growth.
The distribution of CRFs in the sub-
In conclusion, fertilization of crops
in soilless systems do tend to be
more complex but by firstly understanding your crop’s needs and secondly examining the available fertilization options, it is possible to
develop a fertilization program to
suit most grower’s needs.
strate is sometimes not homoge-
Mixing tanks containing the different water soluble fertilizers.