Foliar feeding is a technique of feeding plants by applying liquid
fertilizer directly to their leaves. It has been known for many years that
plants are able to absorb essential elements through their leaves. The
absorption takes place through the stomata of the leaves and also through the
epidermis. Movement of elements is usually faster through the stomata, but the
total absorption may be as great as through the epidermis.
EFFECTIVENESS:
“ Dr. H.B. Tukey” renowned plant researcher and head of the Michigan
State University (MSU) Dept. of Horticulture in the 1950’s, working with
research colleague Sivan H. Wittner at MSU, first proved conclusively that
foliar feeding of plant nutrients really works. They found plant nutrients move
at the rate of about one foot per hour to all parts of the plants .
Dr. H.B. Tukey and Dr. Silvan
Wittner, in association with Atomic Energy Commission, conducted extensive research into the efficacy
of foliar fertilizing. Using atomic
trace data, they were able to show that foliar feeding was eight to twenty times
more efficient than root feeding.
Foliar feeding is an efficient,
effective and economical method of fertilization. The purists are
correct in that it should not be used to replace a good soil fertility program, but it can be a
remarkable yield-booster in conjunction with a well-balanced soil, and it can
be an incomparable problem-solver in
many situations.
Foliar feeding can bypass problems associated with root absorption, like nutrient competition, nutrient lockups, leaching and soil structure
problems. This technology offers rapid rescue response in times of stress -frost, drought, storm damage, pest and disease pressure- and it offers that extra energy boost during
periods of nutrient demand. Foliar
feeding can also be used to manipulate growth energies, i.e. to switch a
plant from growth response to a fruiting response.
The
pores on the leaf, called stomata
(predominantly on the underside), are the main entry point of nutrients, but
all living parts of a plant above ground ( including twigs, branches, buds,
fruits, flowers and stems) can actually absorb nutrients. Although rapidly
absorbed, there is quite a variation between the mobility of various nutrients
once they are in the plant. Nitrogen,
phosphorous, potassium, copper, manganese and zinc are readily translocated to the roots, but calcium, iron, boron, magnesium & molybdenum tend to remain in the leaf after they are absorbed.
In
Lee Fryer’s book entitled “ Food
Power from the Sea”, the comparative efficiency of the foliar route is
highlighted, Fryer contends that only 10% to 30% of NPK Synthetic Granular fertilizers ever
make their way into the crop, due to evaporation, lock ups or leaching, while in
comparison , 80% of foliar nutrients
successfully reach their mark.
THE ESSENTIAL TOOLS.
SPRAY EQUIPMENT
Foliar feeding is most
efficiently achieved with mist-type sprayers. The smaller the particle size,
the better the response and the less fertilizer is required to achieve the end
result. The leaf hairs surrounding the stomata attract nutrients within fine
water droplets more effectively.
CHOOSING THE RIGHT TIME TO SPRAY
·
Foliar fertilizers, particularly those containing multi-hormonal stimulation, are unique
stress relievers. They can be used as invaluable rescue remedies after
transplanting, hail, wind and drought and after spraying herbicide to the
plants as it affects root structure of the plants.
·
It is always best
to foliar spray in the early morning (6am to 9am) or evening (4pm to 6pm) when
relative humidity is high, rather than in the heat of the day. There are two
main reasons for this fact:- Obviously,
if a fine mist is applied, there is a risk that hot sun will evaporate the
solution before it can be beneficial. Secondly, when temperatures exceed 32deg.
C, plants transpire and release rather than absorb moisture.
·
There is another
important factor related to temperatures and spray effectiveness: when
temperatures fall below 11deg. C, metabolic rate and nutrient translocation has
slowed down considerably, and foliar sprays are less effective.
·
It should always
be remembered that the majority of the stomata are on the underside of the
leaf, and consequently this should be the target for spray solution.
·
Finally, there is
very important link between moon cycles and the performance of foliar
fertilizers. The best foliar response is achieved during any of the six days
leading up to a full moon. Any other time is acceptable but always avoid any of
the six days leading up to a new moon, as benefits will be minimal. As the moon
affects the gravitational pull of the tides, it also affects fluid movements
and translocation of nutrients within the plants.
SOURCE : NUTRITION FARMING EXPLAINED WORSHOP MANUAL
By:
Graeme
Sait***
***Graeme Sait is CEO and co-founder of Queensland-based company,
Nutri-Tech Solutions P/L (NTS), which is now a recognised world leader in biological agriculture. NTS
services 12,000 farmers, exports to 25 locations and has developed over 200
products. Graeme is also a writer and educator responsible for the holistic NTS
systems approach. He developed the highly successful Soil therapy and Plant
Therapy services and created the NTS Management Seminars- four eight –hour
workshops, featuring the associated, exam-based “ Certificate in Sustainable
Agriculture”. This certificate course is rapidly becoming a prerequisite for “
nutrition farmers” chasing higher yields and profits via a chemical-free
approach. Graeme is author of over 50 published articles and has conducted an
intensive interview series with the leaders in sustainable agriculture.
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