Introduction Nitrogen Phosphorus Potassium Zinc Iron Manganese Manures Method Of Application Liming Of Coconut Soils Common Salt In Coconut Nutrition Physiological Disorders

• 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 evidenced 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 of 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 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 fertilizers 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 the 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 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 effect of nitrogen in plant metabolism could be achieved only if phosphoric acid and potash also are provided.
• In coconut, it plays an important role in growth as well as to increase the number of leaves the fruit bunches.

• The lower leaves become non-chlorophyllous. As a result they turn yellowish or whitish yellow in colour.
• In addition to decrease in size and number of leaves the plants become stunted and weak. N-deficient plants look like old trees and finally the yields will decrease.
• The N-deficient palm absorbs more quantities of manganese

• Non adoption of recommended doses of organic and inorganic fertilizers in light soils,
• Due to not practicing of giving extra doses of fertilisers to inter crops in multiple cropping system.
• In new plantation gardens and in new pits even though the roots grow in deeper layers, the plants show deficiency (yellowing) symptoms if sufficient nitrogen is not available.
• In alkaline soils, low rainfall areas and in drought prone areas the organic matter is not completely decomposed. In such situations N-deficiency will occur.
• Similarly if sufficient water is not present or efficient drainage facilities are not available, it leads to N-deficiency.

• Phosphorus is found especially in leaves and seeds and also in parts of the plants where vigorous cell division is taking place.
• Phosphorus deficiency results in deficient root development and delayed ripening of fruits.
• 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 in 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.
• It plays an important role in root growth and increased yields.

• Coconut requires low amounts of phosphorus. The applied phosphorus is fixed in the soil for 3-4 months and slowly available to plant. So phosphorus deficiency symptoms occur rarely.
• Due to phosphorus deficiency the root growth decreases.
• Leaves become yellowish, opening of spadix and the formation of nuts is delayed.

Deficiency occurs in acid and alkaline soils

• Potash has its important and specific functions apart from those, which it jointly performs in association with phosphorus.
• It regulates the water economy of the plant and so is indispensable for the rational utilisation of limited water supplies for the production of the highest possible yields.
• It enables the plant to withstand drought.
• Potash is known to help root development, enabling the palm to take up more nutrients from the soil.
• Since potash is particularly necessary for the formation of sugar, fat, and fibrous material, the coconut palm may be expected to have a high requirement of potash.
• Adequate potash metabolism enables the plant to be highly disease-resistant.
• Potash increases yield and improves the quality of plant products.
• It regulates protoplasmic swelling and streaming in plant cells and so directly influences enzyme action in them.
• The movement of iron in the plant is facilitated by potassium and hence it has an indirect effect on the formation of chlorophyll.
• It has been said that a concentration of potassium occurs generally in the growing parts of the plant where life and growth processes are intensive.
• The ash of fully developed coconut tree contains 18 per cent potash while in the old leaf its percentage is 13.75.
• It may thus be seen that the demands of potash are rather heavy in coconut and the importance of its role in the nutrition and physiology of the palms cannot be over emphasized.
• On account of these facts it is certain that potash must be having very vital functions in the coconut palm.
• Potash has an effect on earliness of bearing of the palms.
• Palms receiving potash were observed to begin bearing fruit in the fifth year of planting while palms receiving no fertiliser took eight years to bear.
• It was also seen that nitrogen caused an 8 per cent increase in copra yield while potash gave an increase of 25 to 39 per cent.
• It would seem that the nitrogen/potassium ratio has some influence in the earliness of bearing as well as in copra yield.
• The absorption of potash is interfered with by an excess of nitrogen and phosphoric acid, particularly the former, showing the need for a balanced application of nutrients for optimum effect.
• Increased oil content of copra is observed as a result of optimum potash function in the palm.
• The leaves of palms which are insufficiently supplied with potash are very susceptible to attack by Pestalotia palmarum.
• Potash can reduce the incidence of shoot-rot attack and this has been attributed to the potash content of the nutrients, which increases the resistance of protoplasm to pathogenic organisms.
• The effect of potash on disease resistance is probably to be found in the more rational absorption of water accompanied by a depression of excessive transpiration by the palm.

• Potash deficiency is marked by unsatisfactory development especially of leaves.
• The palms remain small with thin trunks.
• Tip scorching of leaves has been well known to be a nutrient deficiency symptom, which appears to be corrected by potash manuring.
• In comparative analysis of inflorescence about to open with an inflorescence after the kernel is formed shows that there is more than double the quantity of potash in all parts of the younger inflorescence than the older one.
• The percentage of potash in the inflorescence (spathe about to open) is 15.8 per cent on a barren palm compared with 20.46 per cent in a normal bearing palm.
• All these points make it abundantly clear that potash is a nutrient intimately associated with the health, optimum growth and productivity of the coconut palm.
• However, it is reported that application of higher levels of potash might interfere with magnesium uptake and that application of Magnesium sulphate (MgSo₄) at 0.5 Kg (0.17 Kg Mg) per palm per year has given beneficial results. Application of MgSo4 also helps in correcting yellowing of leaves.

• Zinc deficiency symptoms are very rare in coconut.
• Stunting of palms, younger leaves remaining small resulting in a bushy appearance. This is commonly called as rosette or "little leaf".

• It's deficiency occurs mostly in saline soils.

• It plays a key role in the synthesis of chlorophyll. Its availability is more in lower leaves.

• Due to iron deficiency interveinal chlorosis takes place i.e., the place between veins become yellow.
• Formation of burn spots occurs on leaves and these spots coalesce and leads to drying up of tips of veins.

• This deficiency occurs mostly in alkaline soils or soils having high lime content or in ill-drained soils.
• With iron deficiency manganese deficiency also occurs.

• It aids in the formation of chlorophyll in leaves. It is present mostly in lower leaves and provides favourable growth conditions during younger stages of palm.

• Due to Mn deficiency formation of parallel yellowish, non-chlorophyllous stripe on the leaves takes place and finally leads to curling of leaves.
• Appearance of cracks in the cortex of tap root.
• Due to Mn and iron deficiency, 5-20 year old palms exhibit reduced growth, weak stem and reduction in yield. Even though the age of palms is less they appear as 80-90 year old trees and look like phoenix trees. This type of symptoms are commonly called as "pencil point" abnormality or "little old palms".

• In ill drained soils in addition to Mn deficiency other nutrients like Zinc and Copper are also deficient which leads to Pencil point abnormality.
• It occurs mostly in saline soils and also in high lime content soils.

• Coconut palms respond to proper manuring particularly for the reason that coconut soils in general are deficient in major plant nutrients.
• Even if the soil is initially fertile, continuous removal of plant foods from the soil in fairly large amounts, consequent to the unique bearing feature of the palm, is likely to create nutrient deficiencies some time later, unless proper manures are used to make good the loss.
• To forestall such an eventuality, it is wise to adopt a proper manuring schedule from the beginning itself.

• The need to keep the organic matter content of the soil at a satisfactory level has already been explained.
• Green manuring would probably be the best solution to overcome this deficiency.
• Green manuring consists of turning into the soil green plant material grown in situ or brought from outside.
• In the coconut areas of Tamil Nadu the growers are in the habit of applying green leaves to coconut palms.,
• Where soil and other climatic conditions permit, crops such as cowpea, sun-hemp, Daincha and Pillpesara are sometimes grown for green manuring purposes.
• It has, however, been demonstrated by extensive field tests that Crotalaria striata is the most suitable green manure crop.

• The practice of applying materials such as lime and common salt to coconut trees is a long standing one in many coconut growing countries of the World.
• Actual experimental evidence regarding their practical utility under field conditions is yet meagre.
• Lime is supposed to correct soil acidity but at the quantities ordinarily applied, it cannot have any significant influence on soil reaction.
• It can, however, exert a beneficial effect by counteracting the toxic effect of high content of soluble aluminum salts.
• In view of their widespread use by the growers, more detailed investigations are necessary.
• There is a practice in the coastal and backwater areas in India to apply silt and clay to coconut gardens in sandy loam and sandy soils and silt and river sand to plantations in reclaimed clayey soils.
• The use of filter press mud from sugar factories as a soil ameliorant is also practiced.

• 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 monsoon rains.
• It is a common practice to apply manures to coconut in trenches or in shallow basins dug around the tree or broadcast and cover with a plough.
• If a full dose of manures is given to all the trees regularly every year, it is 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 seedlings, 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.

• To ensure 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 factor which leads to their stickiness and liability to water logging.
• Disturbance in nutrient uptake under acid conditions may be compensated by increasing the Calcium 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.
• 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 is at a maximum. 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, liming of coconut soils appears to be important.
• Indeed, the changes in the soil 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.

• 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 it 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 considerations 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 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.

• Button shedding and premature nut fall are commonly observed disorders.
• Possible reasons are drought, poor soil aeration or K deficiency.
• These problems can be easily managed by irrigation, ploughing twice in a year and application of potassic fertilizer.

• Boron deficiency can be corrected by application of 200g of Borax per palm.

• This can be corrected by application of 2,4-D at 30 ppm. (30 mg/lit). This can be sprayed one month after opening of the spathe.

• Soil analysis and application of required micronutrients will solve the problem.

• Application of 1 kg of Muriate of Potash and 200 g of Borax per palm in addition to the regular recommended dose of fertilizer will correct this problem.

• This can be identified by yellow leaves. Application of 500 g Magnesium sulphate will correct the deficiency.

• One kg of sodium chloride per palm per year is recommended in addition to the regular fertilizer to increase the nut yield.

• In coconut root feeding with 40 ppm of NAA reduced the button shedding and increase the nut yield.
• Root feeding with macro, micro nutrients, salicylic acid and NAA improved the nut production in coconut.