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Agriculture > Spices > Turmeric (Curcuma longa)

Crop Management

Organic Farming

Package of practices

Maintenance of buffer zone

In order to cultivate turmeric organically a buffer zone of 25 to 50 feet shall be maintained if the nighbouting farms are non-organic. The produce from this zone shall not be treated as organic. Turmeric being an annual crop, the conversion period required will be two years, Turmeric can be cultivated organically as an intercrop with other crops provided organic methods of cultivation is followed for all the companion crops.

Sources of planting material

Carefully preserved seed rhizomes free from pests and diseases which are collected from organically cultivated farms should be used for planting. However, to begin with seed material from high yielding local varieties may be used in the absence of organically produced seeds. A seed rate of 2500 kg rhizomes is required for planting one hectare.

Preparation of land and planting

While preparing the land, minimum tillage operations may be adopted. Beds of 15 cm height, 1 m width and of convenient length may be prepared giving at least 50 cm spacing between beds. Solarisation of such beds is beneficial in checking the multiplication of pests and diseases causing organisms. The polythene sheets used for soil solarisation should be kept away safely after the work is completed.

At the time of planting apply 25 g powdered neem cake and mix well with the soil in each pit taken at a spacing of 20-25 cm within and between rows. Seed rhizomes may be put in shallow pits and covered with well rotten cattle manure or compost mixed with Trichoderma (10 g compost inoculated with Trichoderma). Turmeric can be planted during April-May with the receipt of pre monsoon showers.

Cultural practices

Mulching the turmeric beds with green leaves is an essential operation to enhance germination of seed rhizomes and to prevent washing off of soil due to heavy rain. This also helps to add organic matter to the soil and conserve moisture during the later part of the cropping season. Judicious mix of leguminous leaves with high nitrogen content and leaves rich in phosphorous like acalypha weed and leaves rich in potassium like calatropis can be used according to availability. The first mulching is to be done at the time of planting with green leaves @ 10-12 tonnes per ha. It is to be repeated again @ 5 tonnes/ha at 50th day after planting. Cow dung slurry may be poured on the bed after each mulching to enhance microbial activity and nutrient availability. Weeding may be carried out depending on the intensity of weed growth. Such materials may be used for mulching. Proper drainage channels are to be provided in the inter-rows to drain off stagnant water.

Manuring

Application of well rotten cow dung or own compost from own form @ 5-6 t/ha may be made as a basal dose while planting rhizomes in the pits. In addition, application of neem cake @ 2 tonnes/ ha is also desirable.

Plant protection

Pests

Regular field surveillance and adoption of phytosanitary measures are required for pest management. If shoot borer incidence is noticed, such shoots may be cut open and pick out larvae and destroy them. Spray neem oil 0.5% at fortnightly intervals if necessary.

Diseases

No major disease is noticed in the crop. Leaf spot and leaf blotch can be controlled by restricted use of Bordeaux mixture 1%. Application of Trichoderma at the time of planting can check the incidence of rhizome rot.

Harvesting and post harvest operations

Turmeric is to be harvested at correct maturity. Depending upon the variety, the crop becomes ready for harvest in 7-9 months, medium varieties in 8-9 months and late varieties after 9 months.

Usually the land is ploughed and the rhizomes are gathered by hand picking or the clumps are carefully lifted with a spade. Harvested rhizomes are cleaned of mud and other extraneous matter adhering to them. The average yield per hectare comes to 20-25 tonnes of green turmeric.

Fingers are separated from mother rhizomes. Mother rhizomes are usually kept as seed material. The fresh turmeric is cured for obtaining dry turmeric. Curing involves boiling of rhizomes in fresh water and the drying in the sun.

No chemical should be used for processing. The cleaned rhizomes are boiled in copper or galvanized iron or earthen vessels, with water just enough to soak them. Boil till the fingers/mother rhizomes become soft. The cooked turmeric is taken out of the pan by lifting the thoughs and draining the water into pan itself. The same hot water in the pan can be used for boiling next set of raw turmeric which is already filled in troughs. The cooking of turmeric is to be done within 2-3 days after harvest.

Rhizomes may also be cooked using baskets with perforated bottom and sides. The mother rhizomes and the fingers are cured separately.

The cooked fingers/mother rhizomes are dried in the sun by spreading in 5-7 cm thick layers on bamboo mats or cement floor. A thinner layer is not desirable as the colour of the dried product may be adversely affected. During night time, the material should be heaped or covered. It may take 10-15 days for the rhizomes to become completely dry. Artificial drying using cross-flow hot air at a maximum temperature of 60°C is also found to give satisfactory product. In the case of sliced turmeric, artificial drying has clear advantages in giving brighter coloured product than sun drying which tends to suffer due to surface bleaching. The recovery of dry product varies from 20-30% depending upon the variety and the location where the crop is grown.

Dried turmeric has a poor appearance and rough dull colour outside the surface with scales and root bits. Smoothening and polishing the outer surface by manual or mechanical rubbing improve the appearance.

Manual polishing consists of rubbing the dried turmeric fingers on a hard surface. The improved method is by using hand-operated barrel or drum mounted on a central axis, the sides of which are made of expanded metal mesh. When the drum filled with turmeric is rotated, polishing is effected by abrasion of the surface against the mesh as well as by mutual rubbing against each other as they roll inside the drum. The turmeric is also polished in power-operated drums. The yield of polished turmeric from the raw material varies 15-25%.

The colour of the turmeric always attracts the buyers. In order to impart attractive yellow colour, turmeric suspension in water is added to the polishing drum in the last 10 minutes. When the rhizomes are uniformly coated with suspension they may be dried in the sun.

Rhizomes for seed purpose are generally stored after heaping under shade of tree or in well ventilated shade and covered with turmeric leaves. Sometimes the heap is plastered with earth mixed with cow dung. The seed rhizomes can also be stored in pits with sawdust. The pits can be covered with wooden planks with one or two holes for aeration.

 

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