are trying to manage raw materials in any production system, we need
to determine the following:
much raw material do I need?
much raw material do I have in stock?
much material do I need to get to ensure that I have enough?
same approach applies to plant nutrition. Let us explore each
much of each nutrient do I need?
crop has its own nutrient requirement and we must adjust our
nutrient supply to suit. Fortunately, the requirement of all of the
major crops have been thoroughly researched and are well known.
Fertilizing exotic crops can present problems and often requires
some educated guessing if the nutrient requirements have never been
is also important to estimate your yield goal. If your crop will be
grown under very good conditions, it is necessary to have a higher
supply of nutrients to get maximum production. However, if crop
growth is expected to be low due to something that you cannot
resolve (for example poor weather conditions), then it makes no
sense to apply high amounts of nutrients that the crop will not use.
much of each nutrient do I have?
is where soil analysis becomes important. Soil analysis indicates
the amounts of plant available nutrients in the soil. It identifies
which ones are in short supply and you can then decide what needs to
it is essential to apply the nutrients that are in short supply, it
is also important that you do not apply nutrients that are already
adequately supplied. Not only is this a waste of money, but it can
lead to pollution problems and may actually reduce production by
causing imbalance of nutrients.
much should I apply?
soil report will give a suggested amount of nutrients to be
applied for the crop you want to grow on that soil. This
recommendation will give very good results, but must be modified to
suit your conditions. For example, if the price of fertilizers
suddenly increases, it may be necessary to reduce the fertilizer
rates. However, if the price of fertilizers drops, you may wish to
apply a 2-crop dose of the immobile nutrients such as phosphorus so
that you will not have to use any when the price increases (this
cannot be done with mobile nutrients such as nitrogen).
report would recommend which nutrients are needed, but will not
recommend which fertilizers to use. This must be done by a person
who understands what is needed and knows what fertilizer materials
are available in your area.