FREQUENTLY ASKED
QUESTIONS
About
Data Interpretation and Fertilizer recommendation method:
Data
are compared with known foliar norms from local and international sources,
using the following approaches:
1)
Values are inspected and compared with so-called critical levels in the
literature.
2)
The balance of nutrients in the plant is evaluated using nutrient ratio or the
DRIS approach of Beaufils.
3)
Soil samples are interpreted with foliar results, and interaction with
irrigation water parameters are also appreciated. Considerations for soil
depth, plantation spacing, irrigation practice, availability of organic manure,
age of plantation etc are also made.
4)
The most difficult step is to make recommendations to improve the condition of
the stand. Foliar analyses can identify the nutritional problems, but
recommendations to overcome the problem (generally a fertilizer recommendation)
can only be based on field experiments. We at ANALAB make fertilizer
recommendation based on available evidence from fertilizer trials conducted
under similar site / climatic conditions at a comparable stand age, if any such
trial results exist. In cases where growth responses to specific fertilizer
applications rates have been quantified, recommendations can be made with
confidence. Where no trial data exist, the recommendations will be based on the
degree of deficiency measured, the site information and any other available
literature sources. Obviously, the degree of confidence in such a
recommendation will be less.
Q:
We have a serious problem in some part of plantation and we cannot wait until
the optimum sampling season. Can I collect samples now?
A: Yes, if the deficiency is severe, we will
probably pick it up through ordinary sampling. If an exceptionally large area
is affected and you require immediate and accurate answers, we can attempt to
correct concentrations obtained in the out-of-season-sample with the aid of
starch analyses. This will cost more and additional laboratory time will be
required, but it can, theoretically, be done.
Q:
Why is it not desirable to base a fertilizer recommendation in a deficiency
situation on the foliar data alone?
A: The
quantity (as opposed to the concentration) of nutrients needed to rectify
imbalances is dependent on the degree of deficiency and the age (size) of the
tree crop at that specific time. Furthermore, the percentage of nutrients
actually taken up (of the quantity applied) is dependent on site, environmental
conditions, competing vegetation species and tree age, to name but a few
factors. The most reliable answer can be obtained with field trials under
controlled conditions.
Q: My trees are dying and I don’t know why.
What do I do since I do not know whether it is caused by poor nutrition?
A: Follow a process of elimination. We recommend
that you look at:
1) silviculture,
2) pests and diseases,
3) nutrition,
in that order, unless you can see symptoms that
suggest nutritional deficiency right from the start. The reason for this is
that few stands will die outright if nutrition is sub-optimal.
1) If you do not have any silvicultural experience, ask an experienced person
to look at your stand. Most problems in young stands are related to poor weed
control and/or problems with site preparation and establishment.
2) If you see any signs of damage by insect pests or diseases, contact local
extention officer. Bear in mind that nutrient imbalances sometimes increase the
susceptibiity to a pest attack.
3) If both the above prove fruitless, or if symptoms of discolouration are
evident, nutrient imbalances are likely to be the cause.
Sampling Procedure | Sample submission form | For international clients