Introduction
- The coconut is a perennial crop and is unique in that once it starts flowering,
the production phase lasts almost throughout the year and all through its life.
- A normal tree produces an inflorescence (flower bunch) which finally
gives rise to mature nuts in about twelve months after the date of opening of
the flower, in the successive leaf axils, at intervals of about twenty eight to
forty days.
- In a normal tree growing under suitable conditions, there
is a continuous process of fruit production right from the primordial stage of
the flower to the final mature nut which becomes ready for harvest at intervals
of about thirty to forty days.
- This will be evident from a close examination
of the crown of a normal bearing palm, where one could see nuts at different stages
of maturity in the successive bunches or inflorescence.
- Therefore, there
is bound to be a steady utilization food material by the coconut tree and consequent
depletion of plant foods from the soil.
- Different estimates of the average
annual loss of the important plant foods from a hectare acre of coconut garden
yielding about 5,000 nuts per year have been reported.
- The quantities
of nutrients removed per hectare will be 62 kg of nitrogen, 25 kg of phosphoric
acid and 93 kg of potash.
- For the proper maintenance of coconut plantations
and obtaining good yields, manuring has to be done judiciously and regularly.
- It has to be noted that in coconut, the effect of manuring or other agronomic
practices on the yield of the trees will be noticed only after a period of about
two and a half to three years since this period is required for the development
of the nuts from the primordial stage to full maturity.
- Therefore, manuring
has to be carried out regularly and systematically every year to maintain the
condition of the trees and obtain good yields.
- There is no gainsaying
the fact that the coconut responds to the application of complete fertilizers-nitrogenous,
potassic and phosphatic manures-especially when the plantations are located in
less fertile or poor soils.
- The response is particularly marked in the
case of the application of potassic and nitrogenous fertilizers.
- Application
of potash (K2O) (to supply 0.75 to 340 to 680 gm per trees per year to the coconut,
has been found to result in increased yields and greater resistance to disease.
- Potash can be applied in the form of ash or muriate of potash.
- Ash,
particularly that obtained by burning coconut fronds, husks, etc., and stored
properly without being subject to the leaching action of rain, may be applied,
the quantity depending upon its potash content.
- In the case of ash, it
is considered desirable to apply in smaller doses at intervals during the course
of the year rather than applying it in one large dose.
- Application of
nitrogenous fertilisers to supply 230 to 455 gm of nitrogen per tree per year
has been found to result in increased yields of coconut.
- This may be
supplied in the form of ammonium sulphate, chilean nitrate or locally available
oilcakes.
- Oilcakes are best applied with the beginning of the monsoon
rains, while it would be desirable to apply fertilisers after the severity of
t he monsoon rain is over and when there is sufficient moisture in the soil.
- Although
coconut palms have not shown as much response to phosphoric acid as to nitrogen
and potash, it is considered desirable to apply 115 to 230 gm of this nutrient
per tree per year to maintain the fertility status of the soil.
- It may,
therefore, be supplied in the form of bonemeal or superphosphate or rock phosphate.
- This may be applied fairly deep in the soil in plough furrows just before
the monsoon rains, with the sowing of the green manure seeds or later along with
the other manures.
The general recommendation for
the manuring of seedlings in India is the following
Year after transplanting | Quantity
(kg) of manures per seedling per annum | Ammonium
Sulphate | Super-phosphate or bone-meal | Muriate
of potash | I year | Nil | Nil | Nil |
II and III years | 0.25 | 0.25
| 0.25 | III and IV years
| 0.50 | 0.25 | 0.50
| V and VI years | 1.00 | 0.50
| 0.75 | VII years onwards
| 1.50 | 1.00 | 1.00
|
Top General
Aspects Of Manuring - There is general response to the application of
potash and nitrogen, while response to phosphoric acid is seen only in certain
restricted situations.
- The response to manuring is conditioned to a large
extent by the availability of nutrients in the soil, but there is no clear idea
as to the threshold values below which response could be expected.
- The
non-response to manuring in the heavy coastal clay soils of Malaya is probably
due to their high natural fertility.
- Potash content is reported to reach
as high as 0.8 per cent.
- A minimum of three years appears to be a reasonable
period for the first response of the trees to manuring to become manifest.
- There
is general agreement that initially high yielders do not respond as much to manuring
as low and medium yielders.
- This indicates the possibility of selective
manuring of the trees especially when the prices of fertilisers are high.
- Broadcast
application of manures is seen to be as good as the application in circular basins
or in trenches.
- Application in linear trenches in between rows of trees
is not as good as the other two.
- It should, however, be realised that
the experiments have been carried out in gardens where the palms have been planted
as a pure crop.
- This situation is never obtained in small holdings where
the palms would be irregularly planted among miscellaneous other forms of vegetation.
- Under these conditions, application of manures in circular basins or
trenches is to be preferred for the following reasons:
- The highest concentration
of roots being close to the palms would result in maximum utilisation of nutrients.
- There is less fixation of phosphates in the soil as the ratio of soil
to fertiliser is less than when broadcast over the soil.
- When manure
is applied broadcast, the entire area has to be ploughed or harrowed to cover
the manures. Loss of fertiliser applied to the surface is possible through run
off.
- Surface manuring may encourage surface rooting which may make the
palms susceptible to drought.
- There may be rank growth of weeds competing
with the palms for plant food, which will cost more to control.
- This
method, largely in favour with the growers, has stood the test of time.
- Much
difference of opinion however still remains in the matter of response by coconuts
to manurial applications.
- The absence of uniform experimental material,
and clear knowledge about the appropriate nutritional requirements, and the long
lag period before results of indicative value could be obtained are responsible
for this state of affairs.
- Probably the use of radioactive tracers in
investigations on coconuts would give quicker and more accurate assessment of
some of these problems.
Top Principles Of
Manuring - The capacity of soils to supply plant nutrients deteriorates
on continued cultivation.
- Fertiliser practices in coconut gardens after
a few years of cropping thus need occasional revision to meet the changing conditions
of the nutrient status of the soil.
- Thus, for practical manuring, it
is important to know how far the effect of the plant nutrient depends on the presence
or absence of another and to what extent cumulative excess of a major nutrient
may adversely affect palm growth.
- The coconut palm is unique in that
once it starts flowering, the production phase lasts almost throughout the year
and all through its life.
- Therefore, there is bound to be a steady utilisation
of food material by the coconut tree and consequent depletion of plant foods from
the soil.
- For the proper maintenance of coconut plantations and obtaining
good yields, judicious and regular manuring is necessary and this has to be an
annual practice.
- It is known that the drain of manurial constituents
by a heavily producing palm is very considerable and when that has taken place
over a series of years, such effects are sure to influence adversely the growth
characteristics of the palms and even to mask the most favourable hereditary characters.
- A great majority of the soils in which coconuts are grown in India are
found to be deficient in organic matter which is considered very necessary for
the proper maintenance of soil structure, and moisture conservation and for obtaining
maximum benefit out of the application of fertilisers.
- Attempts have,
therefore, to be made to ameliorate these conditions and this can be done by incorporating
into the soil bulky organic manures like farm-yard manure, composts, or by a regular
system of applying green manures grown in situ.
- In loose coastal sandy
soils, the application of manures and fertilisers should not be expected to give
very good results since the nutrients are likely to be leached and carried away
depriving the coconut palms of the best benefit if they are not applied at the
proper time and supplemented by bulky organic matter.
- Laterite soils
on which there is a good acreage of coconuts in India, are of inherently low fertility
and tend to be deficient in all plant nutrients.
- Here there is need to
supply all N,P and K ingredients in the form of manures.
- Bulky organic
manures with top dressing of N. P and K will suit this soil best.
- Coconut
plantations on laterite areas during the initial years appear to be highly productive
but unless adequate manuring and soil management practices are given, the plantations
deteriorate steadily.
- Alluvial soils are naturally rich in plant food
factors.
- Sandy soils are not.
- Peaty soils as a rule contain
more organic and less of mineral matter.
- Soils, which have received adequate
quantities of ameliorative supplements such as silts or press mud, etc., need
not receive heavy fertilizer additions.
- It appears to be the view of
some coconut growers that the long continued use of artificial fertilizers exhausts
a coconut palm and that the palm would suffer severe set-back when the fertilizer
application is discontinued.
- Careful and judicious application of both
organic manures and chemical fertilizers ensure both soil conservation and increased
yields.
- Fertilizer application to a large extent depends upon the method
of application or any catch crops are grown what they remove from the soil or
contribute to it.
- These aspects are described under catch crops. Soil
exhausting crops, particularly potash loving, such as sugarcane, pineapple, banana,
tapioca, etc., should not be grown in coconut gardens due to the possible competition
for their potash needs.
- Therefore, should not be grown mixed together
unless they are liberally manured, particularly with potash.
Top
Schedule Of Manurial And Cultural Operations - The following is
a schedule of manurial and intercultural operations followed at the Central Coconut
Research Station, Kasaragod, in Cannanore District of Kerala State.
- The
main soil type of this station is deep reddish loam with a mean annual rainfall
of 3407.3 mm received mostly during the South-west monsoon period.
- This
can, with slight modifications, be adopted elsewhere to suit local conditions
of soil, rainfall, availability of manure, cost of labour etc.
March-April - One ploughing with an iron plough to
prepare the land to receive the summer showers.
May-June
- After a soaking rain is received, sow a green manure crop using proper
seed rate and cover it properly by working a light plough It would be desirable
to give a basal dressing of ash at 20 pounds (10 kg) and cattle manure at hundred
pounds (50 kg) per tree just before the sowing of the green manure crop If bonemeal
or superphosphate is proposed to be applied, it may be incorporated into the soil
before the sowing of the green manure crop.
August-September
- Slash or cut down the green manure crop and plough it into the soil
with a suitable iron plough.
- If ammonium sulphate or muriate of potash
or other manure mixtures are proposed to be applied, they may be broadcast and
ploughed in with the green manure crop at the first or second round of ploughing.
- If cattle manure has not been applied, they may be placed in shallow
basins as already recommended.
- If wild sunnhemp or similar green manure
crop is grown, it may be buried in shallow trenches in between rows of trees.
- The position of the trenches has to be shifted every year so as to cover
the whole area in a few years.
October
- A second dose of ash may be broadcast and a cultivator worked to incorporate
it into the soil. Bunds washed off during rains may be rectified.
December - Work a cultivator (harrow) to create soil
mulch.
Top Bulky Organic
Manures - A great majority of soils, in which the coconut is raised
in India, is found to be deficient in organic matter which is considered very
necessary for the proper maintenance of soil structure and moisture and for obtaining
maximum benefit out of the application of chemical fertilisers.
- Attempts
should, therefore, be made to ameliorate this condition.
- The application
of farmyard manure, compost manure and green leaves in sufficient will increase
the organic matter in the soil.
- Where farmyard or cattle manure is available,
it can be applied at about one hundred pounds (45 kg) per tree, per year.
- But
in view of the limited supplies of farmyard or cattle manure available in the
country, one has to resort to other available sources like compost, green leaves
etc.
- In localities where green leaves are available in plenty, they may
be collected and applied at about 45 kg per tree per year.
- The leaves
may be buried in shallow basins about eight feet (2.5 m) in diameter dug round
the base of the trees or in trenches in between rows of trees and covered with
soil.
- In all cases of application of bulky organic manures, care should
be taken to incorporate them properly into the soil, so as to prevent the breeding
of the rhinoceros beetle (Oryctes rhinoceros) pest, which causes serious damage
to the coconut palms.
Green Manure crops
- Growing a green manure coop in situ and incorporating it into the soil is
probably the easiest and most economical method of augmenting the organic matter
in the soil.
- Therefore it should be the endeavor of coconut planters
to grow green manure crops wherever possible and practicable.
- The green
manure crop selected for cultivation should be a leguminous one, which will renovate
the soil and come up well in the shade of the coconut trees.
- Green manure
crops cowpea (Vigna unguiculata), sun-hemp (Crotalaria juncea) Dhaincha (Sesbania
aculeata) and wild sun-hemp (Crotalaria striata) may be grown depending upon local
conditions.
- Crotalaria striata which is a leguminous weed growing wild
in most of the coconut tracts in particular, has been found to be a very suitable
green manure crop for West Coast conditions.
Top
Common Salt In The Nutrition Of The Coconut Palms - Either as a
direct manure or as an indirect soil ameliorant.
- The addition of common
salt in coconut gardens is a very old and popular practice among coconut growers.
- It is very widely applied to the soil as well as to the top of the palm
often admixed with a little wood ash.
- In lateritic soils, the addition
of common salt in the pits for planting seedlings is known to soften the laterite
bed and help early penetration of the tender roots.
- The view that common
salt helps to conserve soil moisture has not yet been proved by experiments.
- The
results of several studies in different soil types have shown that the concentration
at which common salt may exert a beneficial effect on soil moisture conservation
is very high and in this concentration may adversely affect normal plant growth.
- Whether sodium chloride can release available potash from the soil has
also been not definitely proved by experimental data.
- As a matter of
fact, there is very little evidence that adding sodium salts to a soil increases
the availability of the soil potassium.
- Growers have a feeling that common
salt when applied to the soil has an effect of bringing down the percentage of
incidence of barren nuts.
- In the case of coconut seedlings, moderate
quantities of sodium chloride appeared to be invigorating, but a heavier application
was rather harmful.
- The coconut palm is a semi-halophyte, being able
to live in situations where its roots come in contact with such salt concentrations
as would be lethal to many other plants.
- This shows that it can resist
the action of salt but it need not be that it requires salt.
- There appears
to be a misunderstanding as to the actual amount of salt concentration prevailing
on coastal sands on which the coconut palms thrive well.
- The coastal
soils are not at all saturated with salt on account of the fact that the underground
water in the coastal areas flows seaward from higher inland regions.
- In
many parts of the coast, therefore, fresh water could regularly be struck on land
within a few yards of the waves.
- Salt sprays are liable to deposit small
quantities of the substance on the soil surface, but due to the extreme mobility
of the chloride ion these are leached into the subsoil especially when there is
rain.
- These consideration indicate that while the coconut palm can tolerate
salt concentrations in the soil to a considerable extent and often absorbs salt
into the system and removes it in the different products such as husks, it cannot
be asserted that it has any special preference for it.
- Its partiality
for coastal soils thus appears to have little to do with the alleged salt concentrations
of these areas.
- Nevertheless, it has to be conceded that the use of common
salt has been and still continues to be very popular among coconut growers as
a beneficial agent in the health and productivity of the coconut palm.
Top Liming Of Coconut
Soils - In order that the best effects of fertilisers are derived by
the palms, great care has to be exercised in liming the soils.
- Over-liming
of soils create potash and boron deficiency as well as the condition known as
lime induced chlorosis in palms.
- Where liming materials not containing
magnesium are used, magnesium tends to become a limiting element and may be applied
as magnesium compounds.
- Lime is also said to have the effect of "sweetening"
the soil which, if it is a coastal soil, rich in organic matter may be acid.
- Many
coral-derived soils under tropical conditions which have a vast acreage of coconuts
are low in lime content due to excessive leaching of the surface layers.
- This
is a factors which leads to their stickiness and liability to water loging.
- Disturbance
in nutrient uptake under acid conditions may be compensated by increasing the
Ca concentration in the soil.
- Since the activity of polyvalent nutrient
elements in soil is much reduced by the greater absorption on the soil colloids
of divalent than monovalent ions, a good potassium status of exchangeable potassium
per hectare requires ten times more calcium for adequate nutrient balance.
- In
addition to regulating base saturation and pH, and thus affecting weathering and
humus formation, liming stimulates mineralisation of organic nitrogen and phosphorus,
improves nitrification and reduces aluminum and manganese toxicity in very acid
soils of low organic matter content.
- The coconut thrives best at pH conditions
just on the acid side of neutrality, though it appears to be a plant which needs
a soil giving an alkaline reaction.
- The fact has, however, to be conceded
that the coconut palm can adapt itself to quite a wide range of pH conditions
in the soil.
- All the essential and beneficial elements of plant nutrition
are available to the plants provided they are present in the soil, so long as
the pH is in the range of 6.5 and 7.0.
- When the biological regime in
the soil is most satisfactory, nutrient conditions are favourable without being
extreme and phosphorus availability at a maximum, while soils with higher pH tend
to make the micronutrients unavailable with the exception of molybdenum.
- Since
lime serves a twofold function in the soil, firstly as a plant nutrient factor
and secondly as the agent adjusting the soil reaction and hence the availability
of other soil nutrients to plants, the liming of coconut soils appears to be rather
important.
- Indeed, the changes in the soil due to liming are so many,
so complex, and so inter-related, that it is not possible to ascribe the influence
observed to any one factor.
Top Time
And Method Of Application - The proper time for the application of manures
is when there is sufficient moisture in the soil.
- At the same time care
should be taken to see that the manures applied are incorporated into the soil
properly and not washed off by rain water running through the plots.
- All
precautions should be taken in plantations against soil erosion by previous levelling,
terracing and erecting proper bunds, wherever necessary.
- Weeds should
not be allowed to rob the coconut palms of their manures and their growth should
be checked and controlled properly.
- The manures recommended are best
applied after the receipt of heavy rains of the monsoon.
- It is a common
practice to apply manures to coconuts in trenches or in shallow basins dug round
the tree or apply them broadcast and cover with a plough.
- If a full dose
of manures is given to all the trees regularly every year, it appears desirable
to broadcast the manure and plough it in by using a heavy plough especially in
closely-planted gardens.
- Placement of the fertilisers, especially of
phosphatic manures, at some depth in plough soles or by any other method is considered
advantageous.
- In young plantations and for under-planted seedlilngs,
the manures are best applied round about the young trees till they attain the
bearing stage.
- In widely spaced coconut gardens (8 meters and above),
applying manure mixtures in shallow basins of about 1.5 meters radius is desirable.
- In opening trenches in basins, care should be taken to see that healthy
feeding roots are not unduly cut.
Top The Effect
Of The Nutrients Nitrogen - The supply of nitrogen
which is a constituent of plant cells as well as chlorophyll, the green colouring
matter of leaves, is of great importance for the rapid development and growth
of the trees.
- Nitrogen deficiency is reflected in deficient leaf formation
as well as in restricted growth.
- Nitrogen promotes the development of
the vegetative parts of the plant especially the leaves and shoots.
- The
complete effects of nitrogen in plant metabolism could be achieved only if phosphoric
acid and potash also are provided.
Phosphorus
- Phosphorus is found especially in leaves and seeds as well as in all parts
of the plants where vigorous cell division is taking place.
- Phosphorus
deficiency results in deficient results in deficient root development and delayed
ripening of the fruit.
- Characteristic discolouration often occurs on
the leaves where phosphorus is in short supply.
- Excessive phosphorus
dressings do not act unfavourably on plant growth because part of the phosphate
gets fixed in the soil in forms not readily soluble.
- Potash and phosphoric
acid act jointly in many of their functions.
- The two together help the
formation of sugar, starch and fats as well as in protein synthesis.
- They
particularly promote flowering, fruit setting and root development, speed up ripening
and increase resistance to certain diseases and pests.
- Potassium in the
presence of phosphorus improves the quality characteristics of the produce, such
as flavour, keeping quality, fruit colour, grain weight and size.
Top Nutrient Mixtures
- Since the process of application of manure to coconut plantations, namely,
spreading and covering is a costly operation, it is easier and more economic to
mix the different manures (nitrogenous, phosphatic and potassic) just before application
instead of applying them separately.
- But in doing this, care should be
taken to see that only suitable manures are mixed.
- Ammonium sulphate
should, in no case be mixed with ash or lime, since chemical action will set in
and nitrogen will be lost in the form of ammonia.
- These should, therefore,
be applied separately with an interval of about a month.
- Muriate of potash
and sulphate of ammonia, if mixed, should be used immediately.
- The mixture,
if stored, will become damp in moist air and will cake up.
- The manure
mixtures approved by the Departments of Agriculture are 8:8:16 N:P:K respectively
and these are available in the market under guaranteed analysis.
- An application
of about 2.5 to 3.5 kg of this mixture over a basal application of 50 kg of compost,
farmyard manure or green leaf is recommended per year per adult palm, lower doses
being used for younger palms in pre-bearing stage.
The newly planted young palms may be fertilised according to the following schedule
Age of plantation | Dosage
(Per Palm Per Year) | After
one year's growth | 1/8 Of the adult palm dosage |
After Two year's growth | 1/4 Of the adult
palm dosage | After Three year's growth | 1/2
Of the adult palm dosage | After Four year's growth
| 3/4 Of the adult palm dosage | After
Five year's growth and thereafter | Full Of the adult palm
dosage | - It is expected that new plantations
will attain the bearing stage in six to seven years after planting, if quality-planting
material is used and properly cared for.
- The effect of manuring will
be more pronounced if it is combined with proper irrigation in areas where rainfall
is not sufficient.
Mixtures for sandy soils
Mixture 1 | Per
tree per year | Cattle manure
or compost | 25 to 50 kg |
Wood ash | 10 to 20
kg | Bonemeal | 1
kg | Mixture 2 | -
| Fish guano | 7
kg | Muriate of potash | 1
kg | Mixture 3 | - |
Prawn dust | 7 kg
| Muriate of potash | 1
kg | Mixture 4 | |
Oilcake | 7 to 10
kg | Wood ash | 10
to 20 kg | Bonemeal | 1
kg | Note - Wood
ash at 10 to 20 kg may be used instead of 1 kg of muriate of potash.
- It
is very necessary to grow and incorporate a suitable green manure crop to sandy
and other soils deficient in organic matter.
- Young palms have been found
to respond well to the application of nitrogen and potash.
- Nitrogen may
be supplied in the form of ammonium sulphate 300 to 1000 gm per seedling per year
depending upon the age of the seedling, preferably in two instalments.
- Potash
in the form of ash 5 to 10 kg or potassium sulphate or muriate of potash at 1
kg per seedling per year may be sufficient.
- As the seedlings attain the
bearing stage, the mixtures, recommended for adult trees may be adopted.
- An
occasional dressing of about 0.25 to o.5 kg of superphosphate per seedling is
also desirable for healthy growth.
Top |