Coconut

Water Management

Irrigation

  • Want of sufficient moisture in the soil diminishes the production of nuts, especially in the plantations raised in the sandy and sandy loam soils.
  • It is, therefore, desirable that coconut gardens are irrigated at proper intervals, particularly during the summer months, if there are facilities for irrigation.
  • Though hand-watering is now being done in certain areas, this is not sufficient or extensive probably due to want of adequate irrigation facilities.
  • It has recently been found that filter point tube-wells can easily be installed especially in the coastal areas and subterranean water pumped with the aid of engines for irrigating coconut and other crops.
  • In the sandy soil areas along the sea coast even sea water can be used for watering during the summer months without any ill-effects.

Moisture requirements of the coconut palm

  • In common with most other agricultural crops, moisture is a great limiting factor in the successful cultivation of the coconut palm also.
  • Work on the actual moisture requirements of the coconut palm, however, appears to be very scanty.
  • In the early morning and on rainy days the rate of absorption was very slow.
  • During a long wet season when there are numerous consecutive cloudy days as in the West Coast of India for example, moisture absorption and utilisation by the palms are greatly reduced despite the abundance of water present.
  • In the dry season, the rate of absorption is greatly increased due to increase in the transpiration.
  • The palms have natural adaptation in the leaves for regulating transpiration to some extent.
  • There are no water storage organs in the coconut.
  • The wind makes a decided difference in the transpiration of the leaves, but makes a much greater one when the leaves are in full sunshine as in the dry season.
  • The absorption of nutrients by the palms depends on two sets of factors.
  • Those that occur inside the plant-physiological-and those that occur outside the body of the plant-environment.
  • The age of the palm, its health, etc., govern the rate and amount of transpiration.
  • When unfavourable moisture conditions occur, and in times of severe drought, it is seen that the older leaves fall off or die back.
  • This is possibly an economy measure, since it is the older leaves which transpire more water.
  • Thus the tree cuts down its water requirements to a very appreciable extent.
  • In the case of heavy clay soils, it was found that slow lateral movement of water, and moisture availability were factors leading to the appearance of diseases.
  • The wilting point in a clay soil may occur when there is less than 13 per cent moisture present in the soils especially in the presence of sodium and magnesium salts.
  • High concentrations of these salts hinder absorption through roots.
  • The vitality of the palms was so severely injured during the prolonged drought, that the return of favourable weather conditions is very slowly followed by resumption of normal activity.
  • Only a constant water supply can preserve the vitality of the palm.
  • As the percentage of water to dry matter in a young palm is much greater than in an older palm, the water requirements of a young palm in proportion to its size are greater.
  • That is why young palms are more susceptible to drought conditions.
  • The proper physical composition of the soil is of more important than its chemical composition so long as there is good supply of moisture available to the palms.
  • The greater the need for water for normal physiological processes, the greater will be the injury.
  • An expanded root system as a result of fertilizer application, would only bring the trees in heavy competition with each other, particularly in close plantations.
  • It was found that regular inter-cultivation and manuring help to conserve soil moisture to a considerable extent, especially in the subsoil layers.
  • This may be due to the beneficial effect of inter-cultivation and incorporation of organic matter and found that plots having shade effect due to spread of coconut leaves appear to contain more moisture content in the laterite soil is much higher than that of red loam and sandy soil at the different depths.
  • These conditions are important especially on the West Coast of India where heavy monsoon rains from June to September-October are followed by prolonged period of drought for four to five months from January to May in the year.
  • The number of nuts is controlled not by flower number of pollination but exclusively by the nutritional factors, chiefly water supply.
  • It is interesting to note that the inflorescence of the coconut palm at various stages of development contains 70.17 per cent to 90.07 per cent of moisture.
  • Available potash is a nutrient factor which together with the water supply appears to act as limiting factors in the growth of the coconut palm.
  • Under inadequate moisture availability, potash absorption has been shown to be never optimum even in potash rich soils.
  • However, the coconut palm has inherent capacity for adapting itself to its environments and to varying conditions of moisture and nutrient supply.

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