Intercropping Cultivation Techniques for Licorice in Land Returned from Farmland to Forest

Intercropping licorice in land returned from farmland to forest can both conserve soil and water and increase economic returns, achieving the goal of using the land to support the forest and the forest to support the land, and realizing a "win-win" for both the economy and ecology. Since 2002, Regiment 137 has conducted cultivation trials of intercropping licorice in land returned from farmland. After several years of experimentation and exploration, breakthrough progress has been made.

1. Land selection

Select sandy loam plots of land returned from farmland to forest with relatively low salinity and alkalinity, relatively few field weeds, and good drainage for intercropping licorice. The main tree species planted in the sowing area is wolfberry seedlings; the planting pattern is furrow planting, with a furrow center spacing of 6 m, furrow mouth width of 1.8 m, and furrow back width of 4.2 m. The effective licorice sowing area is 3.8 m. In autumn, deep plow 40 cm for winter irrigation, or carry out spring irrigation in early spring. Before sowing, harrow the land to preserve soil moisture and wait for sowing.

2. Seed treatment

Licorice seeds have a hard seed coat, are impermeable to water and air, and are not easy to germinate; their germination rate under natural conditions is only about 20%, so special treatment is needed to increase the seed germination rate.

Sulfuric acid treatment method: Add 20 mL of industrial sulfuric acid at a concentration of 80% to each kilogram of seeds, stir evenly with a wooden stick so that all seeds are coated with sulfuric acid, then soak the seeds at 20°C for 1 hour to 3 hours. After the seed coat is burned and broken, rinse repeatedly until the sulfuric acid is completely washed off. This can increase the seed germination rate to more than 85%. The advantage of this method is that a relatively large quantity can be treated at one time; the disadvantage is that, due to changes in environmental temperature, the treatment time is difficult to control. If too long, the seeds are easily burned and lose germination capacity; if too short, the seed coat is only slightly damaged and the effect is poor.

Rice milling machine friction treatment method: Use the high-speed rolling of a rice milling machine to make the seeds rub and collide with each other at high speed, thereby damaging the seed coat. This method is most effective for treating large quantities of seeds. Generally, milling once or twice until the seed coat is slightly broken is sufficient, and the germination rate can reach about 95%.

3. Sowing

Pre-sowing preparation: One day before sowing, mix 100 kg of licorice seeds with 0.25 kg of phoxim emulsion. The purpose is to prevent underground pests from gnawing the seeds and young sprouts. After mixing the pesticide, cover and seal the seeds with plastic sheeting and wait for sowing.

Sowing rate: For direct sowing, the seeding rate is 30 kg to 40 kg per sq km. Seed quality standards: germination rate about 85%, purity about 97%.

Sowing time: From after Grain Rain on April 20 to before May 20 is the suitable sowing period for licorice. At this time, the ground temperature has stabilized above 12°C, and the air temperature has stabilized at 20°C to 25°C, which is most suitable for licorice seed germination.

Sowing method: Use a small four-wheel tractor-mounted seeder for hole sowing on plastic film. The film width is 1.2 m, with 4 rows per film, hole spacing of 8 cm, and sowing hole depth of 3 cm to 4 cm. About 6 days after sowing, licorice seedlings emerge one after another; after about 12 days, the seedlings are basically fully emerged. During this stage, attention must be paid to promptly releasing the seedlings.

4. Field management

(1) After licorice seedlings emerge, 2 cotyledons unfold after 3 days to 4 days. If gaps appear in the rows at this time, manual replanting should be organized promptly to ensure full seedling emergence in the field.

(2) When licorice seedlings grow 3 true leaves, larger weeds between the licorice rows should be removed, taking care to protect the licorice seedlings.

(3) When licorice grows 6 to 10 true leaves, the temperature rises and field weeds begin to grow vigorously. At this time, cultivate 1 to 2 times and apply 75 kg to 150 kg of urea per sq km to make the licorice seedlings grow rapidly and close the rows as early as possible.

(4) When licorice grows 6 to 15 true leaves, aphids and green worms may occur. Inspections must be carried out at fixed times every day. Once they occur, pesticide should be sprayed immediately without delay.

(5) At the 6- to 15-true-leaf stage, licorice grows vigorously and is about to close the rows. Another application of urea should be made at 75 kg to 150 kg per sq km, and one timely cultivation should be carried out to remove field weeds.

(6) When licorice grows 15 to 20 true leaves, the seedlings reach a height of 30 cm to 40 cm, and the licorice closes the rows. Field management work is basically finished, and it is enough to assign people to watch over it, but close attention should still be paid to weed growth. If there are too many weeds between the rows, they still need to be pulled out.

(7) Stem and leaf withering stage: In autumn, when the aboveground licorice stems and leaves dry up, harvest them as feed for large livestock. Before freezing, apply 1 winter irrigation.

5. Field management in the second year

After the beginning of spring, directly sown licorice begins to turn green. Water once as appropriate according to soil moisture. When licorice has grown taller than 10 cm, cultivate and weed 1 to 2 times. Large weeds between the rows should be pulled out manually.

In the second year, licorice generally does not need watering during the growing period. In extremely dry years, it can be watered 1 to 2 times.

6. Pest and disease control

The main diseases of licorice include rust and brown spot; there are many kinds of insect pests, and those harming stems and leaves include leafhoppers, aphids, red spiders, and others.

Diseases:

Rust: Infected leaf surfaces produce yellowish-brown scab-like lesions. After the epidermis ruptures, brown powder is released, which is the uredinial stage of the pathogen. From August to September, dark brown telial stages form, causing leaves to turn yellow and fall off.

Control method: Remove diseased and residual plants and destroy them centrally. In the early stage of disease, spray with 15% triadimefon wettable powder at 1000 times dilution or 97% dinocap sodium wettable powder at 400 times dilution.

Brown spot: Leaf lesions are round or irregular, 1 mm to 2 mm in diameter, dark brown in the center, brown at the edges, with gray-black mold-like substances on both sides, which are the fruiting bodies of the pathogen. It mostly occurs from July to August.

Control method: During the disease period, spray 65% zineb wettable powder at 100 times dilution 1 to 2 times. In autumn, clean the garden and centrally handle diseased plant residues.

Insect pests:

Leafhoppers: The nymphs and adults suck the leaves, young buds, and young branches of licorice. Silvery-white patches first appear, then the leaves lose green and turn pale yellow, and finally fall off. They can cause damage throughout the entire growth period, with the most severe damage from June to August.

Control method: Remove elm trees and other overwintering hosts of leafhoppers around the licorice field. At the peak of damage, spray 2.5% deltamethrin emulsifiable concentrate at 1000 times to 1500 times dilution. It is best not to use broad-spectrum insecticides so as to protect natural enemies such as ladybugs.

Aphids, red spiders, leaf miners, and others: For these pests, spray 40% omethoate emulsifiable concentrate at 2000 times to 3000 times dilution, once every 10 days to 15 days, for 2 to 3 consecutive applications.

7. Benefit analysis

It can be seen from the table that directly sown licorice has relatively large growth increments in the second and third years, with large increases in both thickness and weight. Therefore, licorice generally can be harvested as finished product after growing for 2 to 3 years. If it has not formed finished product due to reasons related to land or field management, harvesting can be extended by 1 year. Directly sown land generally has roots about 50 cm deep. A special licorice plow can lift about 40 cm of product; rootlets below 40 cm are abandoned. Calculated according to the actual measured proportion, the loss rate is about 10%, and the damage degree is about 15%, basically meeting agronomic requirements.

For licorice intercropped in land returned from farmland to forest, the fresh root herb yield of 2- to 3-year-old directly sown licorice reaches about 15000 kg to 18850 kg per sq km, equivalent to 4500 kg per sq km of dried mixed-grade strip licorice and 300 kg per sq km of hairy licorice. At current market prices, strip licorice is 6 yuan per kg and hairy licorice is 2 yuan per kg, for a total output value of about 33000 yuan per sq km. The average total input per hectare is between 13500 yuan and 16500 yuan, and the net income per hectare is about 16500 yuan to 19500 yuan, making it an effective way for contract households in the land returned from farmland to forest to become prosperous through hard work.