Detailed Explanation of Licorice Planting Techniques and Field Management Methods

Licoriceis a leguminous plant, with the main types being Glycyrrhiza aspera, Glycyrrhiza glabra, and Glycyrrhiza inflata. Its dried roots and rhizomes are used as medicine, and the crude drug is called licorice. It has the effects of tonifying the spleen and replenishing qi, relieving cough and reducing phlegm, clearing heat and detoxifying, relieving acute pain, and harmonizing the properties of medicines. The cultivation techniques for licorice are introduced as follows.

Soil Selection

Licorice is a perennial herbaceous plant of the genus Glycyrrhiza in the legume family, with well-developed rhizomes and deep penetration into the soil. It is suitable for dry farming, tolerant of salinity and alkalinity, strongly heliophilous, calcium-loving, afraid of waterlogging, and has very strong vitality. For cultivating licorice, it is better to choose sandy soil with a groundwater level below 1.50 m, good drainage conditions, a soil layer thickness greater than 2 m, no hardpan layer within, a pH value of around 8, and convenient irrigation. Plowing is best done in autumn; if there is not enough time for autumn plowing, spring plowing is also acceptable, but soil moisture must be ensured, clods broken up, and the ground leveled, otherwise it will affect full stands and strong seedlings.

Variety Selection and Seed Treatment

Good varieties are the internal factor for achieving high licorice yields. In our county, Glycyrrhiza uralensis and Glycyrrhiza inflata are generally selected as the main varieties. For those using seeds as sowing material, before sowing the seeds should be ground with an electric rice mill, or the seeds should be weighed and placed in a ceramic jar, mixed with 30 mL of 80% concentrated sulfuric acid per 1 kg of seeds, stirred repeatedly with a smooth wooden stick, and kept sealed at 20°C for 7 hours, then rinsed multiple times with clean water and dried for later use; the germination rate can reach over 90%.

Sowing

Licorice can be sown in all three seasons of spring, summer, and autumn, with sowing in May in summer being the best, as the temperature is relatively high at this time, seedlings emerge quickly, and there is still a long growth period before winter. Before sowing, apply 4000 kg of high-quality farmyard manure per mu and 35 kg of diammonium phosphate per mu as base fertilizer. If sowing with seeds, the sowing method can preferably be drilling or hole sowing, with a sowing rate of 2-2.50 kg per mu, row spacing of 30-40 cm, plant spacing of 15 cm, sowing depth of 2.50-3 cm, 3-5 seeds per hole, and after sowing cover with soil and harrow to preserve moisture.

Field Management

Fertilization: In the 2nd and 3rd years, apply 25 kg of diammonium phosphate per mu as a top dressing each spring before the seedlings sprout. Open furrows and apply it 10 cm deep at the side of the rows, with a furrow depth of 15 cm, and cover with soil after fertilization.

Irrigation: In the year of sowing, irrigate 3-4 times, with each irrigation amount generally at 85 cubic meters per mu. The first irrigation is carried out about 1 month after seedling emergence, and thereafter irrigate once every 1 month. In mid-October, irrigate with overwintering water. In the 2nd, 3rd, and 4th years, the number of irrigations can be gradually reduced.

Thinning: When licorice seedlings grow to 15 cm in height, thinning can be carried out, with a plant spacing of 15 cm and about 20,000 seedlings retained per mu.

Cultivation and Weeding: In the year of sowing, generally cultivate 3-4 times, and thereafter the number of cultivations can be appropriately reduced. Combined with cultivation, mainly eliminate field weeds such as dodder.

Pest and Disease Control: The main licorice pests and diseases in our county include rust, powdery mildew, and red spiders. For rust, lime sulfur mixture can be used for control; for powdery mildew, thiophanate-methyl can be used for control; for red spiders, dimethoate can be used for control.

Seed Collection: If artificially cultivated, seeds must be collected every year. During the flowering and pod-setting period, remove the flowers and fruits near the tips of the branches, and large and plump seeds can be obtained. Seed collection should be done when the seeds inside the pods change from green to brown, that is, best at the middle stage of grain filling, when the hard seed rate is low, handling is simple, and the seedling emergence rate is high. The seed collection time should not be too early, otherwise after sowing it will affect the seed germination rate, causing gaps and broken rows, resulting in low yield and poor economic benefits.

Harvest

Licorice generally has relatively good economic benefits when harvested after 4-6 years of growth. Before harvest, the stems and leaves can first be cut off, and deep digging can be carried out along both sides of the rows. After the rhizomes are exposed more than 40 cm above the ground, pull them out with force. The pulled rhizomes should have the reed head, root tail, and lateral roots cut off. Upright rhizomes are called “bang cao”, horizontal rhizomes are called “tiao cao”, and lateral rhizomes are called “mao cao”. “Bang cao” is then graded and sorted, and after the lengths are straightened out, tied into small bundles, dried until semi-dry, then tied into large bundles, and after air-drying, put on the market for sale.