How should licorice be grown to achieve high yield?
I. Seedling raising and transplanting
1. Seedling raising
The seedling bed should be selected from plots of humus soil or sandy loam soil with deep, fertile and loose soil. Apply 2000 kg of farmyard manure, 25 kg of superphosphate and 10 kg of potassium sulfate per mu as base fertilizer, plow more than 40 cm deep, level and harrow fine, and make 110 cm wide flat beds for later use. Licorice seeds have a leathery, glossy seed coat and poor water absorption, so they should be treated before sowing. In production, the sand grinding method is generally used. Mix licorice seeds and clean river sand at a volume ratio of 1:1, put them into a container, stir repeatedly to create friction, and sow once the seed coat is no longer shiny. In March and April, on the prepared bed surface, open four shallow furrows 10-15 cm wide and 1.5-2 cm deep along the direction of the bed ridge, water them thoroughly, evenly scatter the seeds into the furrows, spray 800-fold phorate solution, then cover with fine soil 0.5-1 cm thick and cover with grass to keep warm and moist. Use 5 kg of seed per mu; nurturing one mu of seedlings can plant 5-6 mu of field. (At a temperature of 20 degrees C, seedlings emerge in 5-7 days.) When 50% of seedlings have emerged, remove the covering grass, water to preserve soil moisture, and wait for full emergence. When the seedlings are 15-20 cm tall, apply 20 kg of urea per mu with irrigation, then restrict water afterward to encourage the roots to grow into deeper soil layers and cultivate high-quality seedlings. Licorice seedlings are easily harmed during the seedling stage by underground pests such as cutworms and click beetles, and this is especially prominent in waterlogged lowland and newly reclaimed land. In addition to increasing the amount of phorate at sowing, the control method should also apply phorate once each on the 40th day and 100th day after sowing, with the dosage controlled at 1000-1500 fold, applied by drenching the plants or with irrigation water. In hot and humid seasons, licorice is prone to powdery mildew. First, scattered dot-like and cloud-like powdery white attachments appear on the underside of the leaves, then spread to both sides of the leaves, causing the leaves to yellow and wither prematurely and seriously affecting seedling quantity. The control method should emphasize one word: “early”, that is, early detection and early control. In the early stage of disease, spray with 35% triadimefon 1000-1200 fold solution for control, once every 5 days, for 3 consecutive times. Metalaxyl and others can also be used for control. After careful cultivation for one year, transplanting can be done in February of the second year.
2. Transplanting
Licorice is drought-tolerant, cold-tolerant, salt-alkali-tolerant and highly adaptable. Transplanting fields should preferably be sandy loam soil with deep, loose and fertile soil. After the land is selected, apply 3000 kg of farmyard manure, 50 kg of superphosphate and 20 kg of potassium sulfate per mu as base fertilizer, plow 35 cm deep, level and harrow fine, and make 110 cm flat beds. In mid-to-late February, starting from one end of the seedling bed, dig more than 40 cm deep, carefully dig out the seedlings, making sure the roots are longer than 35 cm, cut off dead branches, and keep at most 3 rhizomes. The seedlings should be planted as soon as they are dug up, and must be strictly prevented from losing water and drying out. On the prepared bed surface, open three small furrows 15 cm wide and 15 cm deep along the direction of the bed ridge, and place two rows of seedlings alternately in each furrow, with root heads 12-15 cm apart. When covering with soil, keep the root head 5 cm above the bed surface and the root tail 15 cm below the bed surface, with the rhizomes naturally extended. After covering with soil, press firmly with the feet, water thoroughly once, and when the bed surface no longer sticks to the feet, hoe shallowly to preserve soil moisture.
3. Field management
Seedlings begin to emerge about 15 days after planting. After full emergence, apply 15 kg of urea per mu with irrigation to promote seedling growth. From the end of May to early June, apply 30 kg of diammonium phosphate per mu in furrows, then water after application. During this period, fertilize and water scientifically to ensure vigorous seedling-stage growth and strive for early row closure. In the rainy season, do a good job of dredging ditches and draining water to prevent powdery mildew. Before freezing, water for overwintering and broadcast 3000 kg of finely crushed farmyard manure per mu to help overwintering. In February of the second year after planting, cut off the aboveground residual stems, water once for green-up, and hoe shallowly when the bed surface no longer sticks to the feet. Hoeing should be shallow to avoid damaging the rhizomes in the watered soil layer. When the seedlings are 20 cm tall, broadcast 30 kg of diammonium phosphate per mu, then water after application. After that comes an important period of licorice growth. Every 10 days, spray 75 kg of 0.3% potassium dihydrogen phosphate solution on the leaves, for 3 consecutive times. Entering the late growth stage, strictly control watering; before the flood season arrives, prepare for drainage, and alternately spray mancozeb and carbendazim to prevent powdery mildew.
4. Pest and disease control
In licorice production, insect pests are mostly cutworms and wireworms, and diseases are mostly powdery mildew. These two are the main causes of yield reduction. The control methods have been mentioned above and are emphasized here for attention. Other pests and diseases can be controlled according to symptoms.
5. Harvesting and processing
Harvesting can be done from the Autumn Equinox of the second year after planting to before spring sprouting of the third year. Start digging from one end of the bed, dig out the whole root system completely, dig out the rhizomes cleanly, cut off stems and leaves, shake off the soil and sun-dry. After drying, tie into bundles and they can be sold. The roots and rhizomes can also be tied separately and sold separately. Licorice commodities are best when dry, free of impurities and rich in powder. The general yield is 600-1000 kg per mu.
II. Rhizome propagation
1. Land selection and preparation
Usually choose sandy loam soil that is fertile, loose in texture, well drained and low in salinity and alkalinity. During land preparation, a tractor is usually used to plow the land, plowing about 20 cm deep, and at the same time apply 2000-2500 kg of barnyard manure per 667 sq m as base fertilizer, then level and harrow fine, and make beds 50-60 cm wide for planting. The plowing depth should reach more than 40 cm.
2. Selecting seed stems
When harvesting licorice in February, select straight, thick, short-internode rhizomes with adventitious roots at the nodes as seed stems. Cut the selected seed stems into small sections 15 cm long, so that each section has at least three nodes with buds. Soak the cut seed stems in 30 ppm gibberellin solution for 3-5 minutes, then plant immediately.
3. Planting
On the prepared bed surface, open three small furrows 15-18 cm wide and 5-7 cm deep along the direction of the bed ridge. Place two rows of seed stems in each furrow, end to end, spray 800-fold phorate solution, then cover with soil so that the seed stems are 4-5 cm below the bed surface, press firmly with the feet, water thoroughly once, and when the bed surface no longer sticks to the feet, hoe shallowly to preserve soil moisture and raise soil temperature.
4. Field management
Licorice propagated from rhizomes emerges relatively slowly; at a soil temperature of 18 degrees C, it takes about 20 days to reach 80% emergence. Therefore, during this period, drought resistance and soil moisture preservation must be done well to keep the bed surface moist and favor emergence. Seed stems forced with gibberellin are slender after emergence, and daminozide or chlormequat can be sprayed according to the instructions to make them thicker and stronger. After full emergence, broadcast 15 kg of urea per mu and spray 30-60 kg of 0.3% potassium dihydrogen phosphate solution. After that, frequently hoe shallowly to eliminate weeds, actively control underground pests, and ensure full and vigorous seedlings. The management after entering June and the management methods for the second year are basically the same as those for transplanting, so they will not be repeated.