Irrigation

Irrigation requirement of coconut

Irrigation recommendation for Coconut on Agro Ecological Unit (AEU) basis

 Drip irrigation

• In the traditional system of irrigation followed in coconut gardens such as flood irrigation, basin irrigation etc. irrigation efficiency is only 30 to 50 per cent due to considerable wastage of water.
• In addition, cost on inputs like labour and energy in adopting these systems are high.
• Scarcity of water and increasing cost of labour and energy are deterrents in adopting these traditional irrigation systems.
• Under these circumstances, drip irrigation is the most suitable system of irrigation to coconut.
• Some of the major advantages of drip irrigation are: it saves water, enhances plant growth and yield, saves energy and labour, most suited for soils having low water holding capacity and undulating terrain, reduces weed growth and improves efficiency of fertilizers.
• For coconut, generally, three to four drippers are given per palm.
• The water requirement for an adult palm is 40 to 50 litres /day

 Weeding and interculture

• Keep the pits free of weeds by periodical weeding. Remove the soil covering the collar of seedlings.
• As the seedlings grow fill up the pits gradually by cutting the sides.
• Proper intercultivation provides control of weeds and creates soil mulch.
• Any tillage system (ploughing, digging, raking or forming mounds) that provides soil mulch and control weeds may be followed depending upon local conditions.
• For laterite, sandy and red sandy loam soils give two ploughings or diggings in May-June and September-October and one raking in January.
• In areas where surface run off is more, form mounds in September-October and level them in November-December.

 Drought management in coconut gardens

• Coconut produces nuts round the year.
• Therefore, adequate supply of water is essential for its proper growth.
• Soil moisture is essential for the absorption of nutrients by roots.
• Moisture stress leads to stunted growth, drooping of leaves, immature nut fall and decreased yield.
  Importance may be given on the following aspects so as to ward off stress:
  1. Husk burial for moisture conservation
• Burying of fresh or dried coconut husk around the palm is a desirable practice particularly for moisture retention.
• The husk can be buried either in linear trenches taken 3 m away from the trunk between rows of palms or in circular trenches taken around the palm at a distance of 2 m from the trunk.
• The trenches may be of 0.5 m width and depth.
• The husks are to be placed in layers with concave surface facing upwards and covered with soil.
• The beneficial effect of husk burial will last for about 5-7 years. Instead of husk, coir pith can be buried @ 25 kg per palm per year.
  2. Mulching
  
• Mulching is an effective method of conserving soil moisture.
• Mulch the coconut basins with green / dry leaves at the close of northeast monsoon (October-November).
• Mulching also adds organic matter to the soil and reduces the soil temperature.
• Do not disturb soil in the coconut garden during summer months.
• In level lands, during rainy seasons excess water may be conserved in small trenches dug out in the plantation.
• In sloppy areas, land may be terraced and trenches dug across. This will facilitate maximum percolation of rainwater and water conservation.
• For moisture conservation, lowermost 3-5 leaves may be cut and removed.
• Provide adequate shade for the transplanted seedlings for 1-2 years.
• To minimize the sun scorch on the srunk, application of lime solution on the trunk up to a height of 2-3 m at the start of the summer season is recommended.
  3. Green manure and cover crops
  Green manure and cover crops recommended for cultivation in coconut gardens are:
  a) Green manure crops: Crotalaria juncea (sunhemp), Tephrosia purpurea (kolinji), Indigofera hirsuta, Pueraria phaseoloides
  b) Cover crops: Calapagonium muconoides, Mimosa invisa, Stylosanthes gracilis
  c) Shade-cum-green manure shrub: Tephrosia candida
• Sow cowpea seeds more towards the periphery of basins taken at a radius of 2.0m from the base of the palm for green manure during April-May with the onset of premonsoon rains.
• When a few plants start flowering, uproot the entire plants and incorporate into the soil during August- September and cover the basins with soil.
• This will increase the water holding capacity of soil.
• Calapagonium can be grown either as green manure or cover crop.
• Tephrosia is especially suited for planting around seedling pits for summer shade and as a source of green manure in the rainy season.

 Intercropping and mixed cropping

• Schedules for inter/mixed cropping may be drawn up based on the canopy size, age and spacing of palms.
• In general, palms in the age group of 8-25 years are not suitable for inter and mixed cropping.
• However, cereals and tapioca are recommended as intercrops in young coconut plantation upto 3-4 years.
• Since ginger and turmeric are shade tolerant crops with shallow roots, they can be intercropped in coconut garden even in the age group of 15-25 years. It ensures better land utilization, solar energy harvesting, efficient water use, utilization of soil nutrient resources, more returns and an insurance against crop failure.
• Under conditions of wider spacing i.e. beyond 7.6 m, intercropping is possible irrespective of the age of the palms. The following crops are recommended as intercrops
• Cereals: Rice, maize
• Legumes and pulses: Groundnut, horse gram, cowpea.
• Tubers: Tapioca, sweet potato, yams, colocasia.
• Spices and condiments: Ginger, turmeric, chilly, pepper, nutmeg, cinnamon, clove.
• Fruit plants: Banana, pineapple, papaya.(Banana variety Palayankodan is recommended in the reclaimed soils of Kuttanad. Three suckers per clump have to be retained).
• Beverage crop: Cocoa
• Fodder grasses: Hybrid Napier, guinea grass.
• Gliricidia (Gliricidia sepium) may be planted as single row intercrop, between rows of coconut during the first year of planting coconut seedlings in pits of size 30 cm x 30 cm x 30 cm spacing of 2m.
• The Gliricidia poles will be ready for felling/ harvesting within 5-6 years of planting.

 Crop cafeteria for multiple cropping in coconut garden

Perennials: Cocoa, nutmeg, pepper, clove,lemongrass and cinnamon.
Annuals:

• Kharif: Rice, maize, groundnut, ginger, turmeric, chilli, yams, colocasia, red gram, vegetables, sweet potato, tapioca, banana, pineapple, papaya and fodder grass
  
• Rabi: Sesame, horse gram, red gram, vegetables, cowpea, sweet potato and banana.
  
• Summer: Vegetables