Turmeric serves various purposes

According to agricultural statistics, turmeric cultivation spans nearly 1000 hectares in Sri Lanka. While the country once relied heavily on imports, recent years have seen a reduction in dependency.

Curcumin

The vibrant color of turmeric is attributed to its key component, curcumin, whose concentration influences the shade of turmeric. Turmeric typically contains between 2% to 5.4% curcumin, with Sri Lankan varieties boasting higher levels ranging from 4% to 6.4%. Turmeric rich in curcumin, particularly at 5.4%, commands significant demand internationally due to its superior quality and recognized antioxidant properties.

A 2017 study affirmed that turmeric cultivated in Sri Lanka contains over 2.02% curcumin, surpassing the curcumin content found in imported Indian turmeric.

Do you know? In the year 2010,

* Imports of dry turmeric totaled 4,196 metric tons, sourced from India, Singapore, Myanmar, and China.

* The export volume of all turmeric products amounted to just 13.3 metric tons.

* Earned 11.2 million rupees in foreign exchange.

To curtail foreign exchange expenditure on turmeric imports and bolster export revenues, the imperative is to stimulate domestic turmeric production. This strategic approach aligns with the primary objective of this article, aimed at fostering self-sufficiency and amplifying Sri Lanka’s presence in the global turmeric market.

Major Cultivation Areas

Turmeric cultivation thrives both as a standalone crop and as an intercrop with coconut cultivation, particularly in regions with high potential like wet and middle zones, as well as in previously untapped areas such as the Ampara district. Turmeric also suits gardening purposes and can be grown under shade in dry zones with adequate water supply.

Botanical characteristics

Belonging to the genus Zingiberaceae, the turmeric plant was originally classified under the botanical name “Curcuma longa”. This herbaceous plant comprises an underground rhizome and a pseudo-aerial stem adorned with broad leaves, reaching heights of 60–90 cm (2–3 ft). The pseudo-stem typically bears 6-12 dark green leaves, with the apical end wider than the basal end.

The primary underground stem serves as a reservoir for food reserves and gives rise to turmeric tubers, also known as rhizomes. These rhizomes branch out from the main stem and boast a dark orange to yellow hue, accompanied by the characteristic aroma and flavor synonymous with turmeric.Crop installation

Varieties

While numerous local turmeric varieties exist, specific identification remains elusive. Imported varieties like Gunter, Puna, and Madurasi Majal are cultivated alongside local variants.

Planting material

Selecting disease and pest-free, high-yielding rhizomes is imperative for successful planting. Mature finger rhizomes are preferred, exhibiting well-ripened, medium-sized tubers with 1-2 buds, weighing approximately 30-35 grams. To mitigate fungal disease, soaking selected tubers in an anti-fungal solution for 10 minutes before planting is recommended.

Climate and soil

Turmeric thrives in diverse climatic conditions, including high-altitude regions up to 1,500 meters above sea level. Even in arid zones, irrigation can support successful cultivation, highlighting its resilience to varying moisture levels.

The ideal annual rainfall for turmeric cultivation exceeds 1,500 mm, although irrigation can supplement moisture requirements in drier regions. Moreover, the optimal ambient temperature for robust growth falls within the range of 20 ºC to 35 ºC.

In terms of soil suitability, turmeric demonstrates versatility, thriving in different soil types. However, well-drained sandy loam soil enriched with organic matter is particularly conducive to its cultivation. This soil type, which also supports successful coconut cultivation, fosters optimal growth conditions for turmeric. Conversely, poorly drained, rocky, gravelly, and clay soils are unsuitable for turmeric cultivation, hindering its development and yield potential. Maintaining a soil pH between 5.5-6.5 is critical for ensuring nutrient availability and facilitating healthy plant growth.

Turmeric cultivation primarily occurs during the spring season, coinciding with March or April rains. However, in dry regions, cultivation extends to the months of October and November to capitalize on favorable growing conditions. While turmeric thrives in sunlight, it is often intercropped with shade-providing crops like coconuts and bananas. However, excessive shading can compromise yield, underscoring the importance of balanced sunlight exposure for optimal growth and productivity.

Field planting with coconut

Leave a distance of 6-7 feet from the coconut tree and establish turmeric beds between coconut rows. This arrangement minimizes soil erosion and ensures efficient land use. Prepare the field by loosening the soil to a depth of 35-40 cm, ensuring a fine soil texture. Incorporating 3-4 kg of half-burnt paddy husk (charcoal) per 1 square meter of the bed enhances soil fertility and structure.Construct beds or ridges of dimensions adaptable to plantation requirements, typically with a height of 18-20 cm. Maintain drains between beds at a depth of 18-20 cm to facilitate water drainage and prevent waterlogging.

Within each bed, adhere to specific planting guidelines:

• Maintain a distance of 30 cm between rows to accommodate plant growth and facilitate access for maintenance.
• Space turmeric plants within rows at 30 cm intervals, ensuring optimal utilization of bed space.
• Plant turmeric tubers at a depth of 5-7.5 cm in the prepared soil, promoting proper root establishment and growth.

In instances of insufficient soil moisture post-planting, irrigation should be provided to support plant establishment and growth. If the soil moisture is insufficient after planting seed tubers, irrigation should be provided.

Typically,

• One hectare requires 1500-2000 kg of seed tubers,
• While in coconut cultivation as an intercrop, the seed requirement is approximately 650 kg per hectare.
• For a bed measuring 120 cm by 300 cm, approximately 1-1.25 kg of seed tubers is needed.

Crop management

Mulching

To maintain optimal conditions for growth, it’s recommended to mulch the beds to a depth of 2-3 cm immediately after the emergence of seed tubers. This practice effectively manages weeds and conserves soil moisture. Suitable materials for mulching include leaves, coconut fronds, straw, paddy husk, or gliricidia, which also contribute organic matter to the soil.

Weed Control

i. The initial weed control should be carried out approximately one month after planting the seed potatoes. If necessary, a thin layer of mulch can be reapplied.

ii. The second weed control should occur around three months after planting. Simultaneously, applying a layer of mulch helps to safeguard soil moisture levels.

Fertilizer recommendations

Turmeric cultivation necessitates the replenishment of nutrients depleted from the soil during the previous season’s harvest. Fertilizers should be applied post-weeding and thoroughly mixed into the soil before mulching. Application can be synchronized with rainfall, or water should be provided promptly afterward. Additionally, the incorporation of Gliricidia leaves serves as an organic fertilizer, diminishing reliance on chemical alternatives while preserving soil moisture.

For a bed measuring 120 cm by 300 cm

Basic Fertilizers:

• Manure or compost: 5 kg
• Triple Super Phosphate (TSP): 50 g

Season	Time	Urea (g)	M.O.P (Muriate of Potash – g)
First Application	1 month after planting	33	50
Second Application	3 months after planting	33	50

Harvest and Post-Harvest Practices

Harvesting

Harvesting of turmeric is typically conducted 8-10 months post-planting, signaled by the yellowing and drying of leaves. For turmeric planted in March or April, harvest time falls in December or January. Care should be taken during harvesting to avoid damaging the rhizomes, and soil particles adhering to them should be gently removed using a wooden implement. Subsequently, the leaves and roots are trimmed off.

Processing

• Mother and finger rhizomes should be meticulously separated and washed, ensuring removal of all stem parts.
• After washing, the rhizomes should be left to dry for approximately a day.
• Mother rhizomes are then cut into smaller pieces.
• Boiling the rhizomes in water for about 30 minutes, repeated three times with a well-covered container, softens them. Alternatively, steaming can be employed.
• Following boiling, the turmeric is left at home for a day and then dried in the sun. Initially, drying is performed in the morning for 3 days, from 11:00 a.m. to 1:00 p.m., limiting exposure to strong sunlight to 3-4 hours. Continuous drying is necessary thereafter, completing the process in 10 days.
• Properly dried turmeric emits a metallic sound when shaken.
• Dried rhizomes are rubbed on a rough surface to achieve a bright yellow color, a process that can be carried out manually or mechanically.

Storage of Raw Turmeric

It is advisable to store turmeric in a cool, dry place, sheltered from rain. A layer of paddy husk, approximately 7 cm (3 inches) thick, is spread on the ground, followed by alternating layers of turmeric rhizomes and paddy husk. This simple method allows turmeric rhizomes to be stored for several months effectively.