Ginger, an indigenous plant, is an important spice crop of the world. It is valued in medicine as a carminative and stimulant of the gastro-intestinal tract. Dry ginger is used for the manufacture of oil, oleoresin, essence, soft drink, non-alcoholic beverages and vitaminesed effervescent soft drinks. India is the largest producer and exporter to more than 50 countries accounting for more than 70% of world production.
The botanical name of ginger is Zingiber officinale L. which belongs to the family Zingiberaceae. Ginger is a herbaceous perennial with underground rhizomes having serial leafy shoots of 0.5 to 0.75m height; leaves sheathy, alternately arranged, linear with 15 cm long and sessile flowers borne on a spike, condensed, oblong and cylindrical with numerous scar bracts; flowers numerous yellow in colour with dark purplish spots, bisexual, epigynous, stamens only one, ovary inferior, three carpelled; fruit an oblong capsule, seeds glabrous and fairly large.
Climate and Soil
Ginger grows best in warm and humid climate. It is mainly cultivated in the tropics from sea level to an altitude of 1500m, both under rainfed and irrigated conditions. For successful cultivation of the crop, a moderate rainfall at the sowing time till the rhizomes sprout, fairly heavy and well-distributed showers during the growing period, and dry weather with a temperature of 280 to 350C for about a month before harvesting are necessary. Prevalence of high humidity throughout the crop period is desirable. Ginger thrives best in well-drained soils like sandy or clay loam, red loam or lateritic loam. A friable loam, rich in humus are ideal. However, being an exhaustive crop, soil should be rich in fertility.
Several cultivars of ginger are grown in the different ginger growing areas in India. They are generally named after the localities or places where they are grown. Some of the more prominent indigenous types are Maran (Assam), Kuruppampadi, Ernad and Wynad local (all from Kerala). A high yielding introduction Rio-de-Janeiro has become very popular among the growers. Its yield potential is 25 to 35 tonnes per ha. The fiber content is 5.19 % and dry ginger recovery is 16-18 %. Recently, High Altitude Research Station, Pottangi (Orissa) has released three improved varieties.
The best time for planting ginger in West Coast of India is during the first fortnight of May with the receipt of pre monsoon showers, while in North Eastern states, it is during April. Under irrigated conditions, it can be planted well in advance during the middle of February or early March.
Preparation of land
Preparation of land starts with the receipt of early summer showers. The land is to be ploughed 4 to 5 times or dug thoroughly to bring the soil to fine tilth. Weeds, stubbles, roots etc. are removed. Beds of about one metre width, 15-cm height and of any convenient length are prepared at an interspace of 40-50 cm in between beds. In the case of irrigated crops, ridges are formed 40 cm apart.
Ginger is always propagated by portions of the rhizomes, known as seed rhizomes. Carefully preserved seed rhizomes are cut into small pieces of 2.5 5.0 cm length weighing 20-25 g, each having one or two good buds. The seed rate varies from 1500 to 1800 kg per ha from region to region. The seed rhizomes are treated with 0.3 % Dithane M 45 for 30 min, drained and planted at a spacing of 20-25 cm along the rows and 20-25 cm between the rows.
Manures and fertilisers
At the time of planting, well decomposed cattle manure or compost at the rate of 25-30 tonnes per ha along with 2 tonnes of neem cake is to be applied along with 50 kg P2O5 and 25 kg K2O. They may be applied either by broadcast over the beds prior to planting or applied in pits at the time of planting. Besides, 75kg of Nitrogen /ha is recommended which is to be applied in two equal split doses at 40 and 90 days after planting. The plants are to be earthed up, after each top dressing with the fertilizers and beds rectified.
Mulching the beds with green leaves is an important operation for ginger. Besides a source of organic manure, mulching prevents washing of soil, conserves soil moisture, smothers weed growth and improves the physical properties of the soil. The first mulching is done at the time of planting with 12.5 tonnes of green leaves and the second mulching is given after 40th day and 90th day with 5 tonnes of green leaves per hectare immediately after weeding and supplication of fertilizers. Daincha can be raised in the interspaces of beds immediately after planting ginger and they can be uprooted before second mulching and may be used for second mulching after earthing up.
Harvesting and curing
Harvesting is done from 6th month onwards for marketing the produce as green ginger. The rhizomes are thoroughly washed in water two or three times to remove the soil and dirt and sun dried for a day. For preparing the dry ginger, the crop is harvested between 245 to 260 days. When the leaves turn yellow and start gradually drying up, the clumps are lifted carefully with a spade or digging fork and the adhering soil removed. The average yield per ha varies from 15 to 25 tonnes.
For preparing dry ginger, the produce is kept soaked in water overnight. The rhizomes are then rubbed well to clean them. After cleaning, the rhizomes are removed from the water and the outer skin is removed with bamboo splinters having pointed ends. The peeled rhizomes are washed and dried in sun uniformly for one week. The dry rhizomes are rubbed together in order to get rid of the last bit of the skin or dirt. These are called unbleached ginger. To get good appearance, peeled rhizomes are soaked in 2% limewater for 6 hours and then dried and this is known as bleached ginger. The yield of dry ginger is 16-25 % of the fresh ginger depending on the variety, location etc.