Detailed Explanation of Licorice Planting Methods and Technical Requirements

1. Selection of planting site. Under different climate and soil conditions, the yield and quality of licorice vary considerably. Licorice has strong adaptability to temperature conditions, while moisture conditions play a decisive role in licorice yield. According to the author's research, in regions of China's temperate zone with 300-500mm of precipitation, the rainfall in normal years can basically meet the growth needs of licorice, and it can be cultivated on land without irrigation conditions; however, to obtain high-quality transplant seedlings, the seedling nursery should have irrigation conditions. In areas with annual precipitation below 200mm, to obtain high quality and high yield, when there is no sufficient groundwater directly available for licorice use (groundwater level 2-3m), both the seedling nursery and the transplant site must have irrigation conditions. In areas with low precipitation (below 200mm) and no irrigation conditions, the planting site should be selected on both banks of rivers where the groundwater level is above 2-3m or in low-lying sections with good water-collecting conditions. In addition, in areas with high precipitation, sections that accumulate water during the rainy season should be avoided. Licorice has a relatively wide adaptability to soil, and sandy loam to light loam soil with a pH of around 8.0, a salt content below 0.3%, and deep, loose, stone-free texture is preferable. Special attention should be paid to introduction and cultivation in areas outside the natural distribution range: only after completing one full cultivation trial cycle, and based on a comprehensive evaluation of the medicinal material's yield, quality and economic benefits, should a decision be made on whether to carry out base-scale commercial cultivation.

2. Seedling raising techniques. Licorice seeds have a high hard-seed rate, and generally untreated seeds have a natural germination rate of less than 20%. The impermeability of the seed coat is the main reason for the difficulty in seed germination and seedling emergence after sowing. Treatment methods such as soaking in concentrated sulfuric acid, repeated soaking with warming, and grinding with a rice mill can all break seed dormancy. In current production and cultivation, grinding with a rice mill is mostly used for seed treatment, that is, grinding 1-2 times with a rice mill, to the extent that no seeds are seen to be broken. This method costs little, is convenient and reliable, and is suitable for large-area planting.

The suitable temperature for licorice seed germination is 15-30°C; below 5°C germination cannot occur, and above 40°C mold and rot are likely to occur. The suitable soil moisture content for seed germination is above 7.5%. The sowing period for seedling raising should be timely and early to extend the growth period. Spring sowing is in April-May, with the specific time varying by region; generally, it is advisable when the ground temperature is stable above 10°C. For large-area sowing and seedling raising, the sowing rate is generally 90-120Kg/hm2, and for direct sowing cultivation 45-60Kg/hm2, with a row spacing of 10-15cm and a soil covering thickness of 2-3cm; the soil covering thickness on sandy land should be appropriately increased compared with loam land.

Licorice likes light, and especially the seedlings grow slowly and are not tolerant of shading, being easily covered by weeds. If weeds are not removed in time, a large number of seedlings will die. Therefore, strengthening intertillage and weeding is very important. Weeds should be removed early, when small, and completely. Because licorice seedlings are not drought-tolerant, in places with irrigation conditions, timely irrigation should be carried out, and 2-3 irrigations per year should be given depending on soil moisture. For heavy clay or heavily saline-alkaline soil, irrigation before sowing can be used to press down salt, and no irrigation after sowing, to prevent surface crusting and salt return. To ensure high yield and high quality, attention should be paid to scientific fertilization. While applying organic fertilizer, compound fertilizer and micro-fertilizers should also be applied; fertilization can also be formulated according to soil conditions, and special fertilizer trials can be carried out to better promote seedling growth.

3. Transplanting techniques. After seedling raising, transplanting can be carried out in the autumn of the first year before the soil freezes, or in the spring of the second year after the soil thaws. First, seedlings are lifted and graded; high-quality seedlings should have a root crown diameter above 0.8cm and a root length of 30-40cm. During the process from lifting seedlings to transplanting, water loss from the seedlings should be strictly controlled. Two transplanting methods can be used: flat planting (abbreviated as pingzhi) or oblique planting (abbreviated as xiezhi). Flat planting is placing the seedlings horizontally in the planting furrow with the head and tail parallel to the ground; oblique planting is placing the seedlings obliquely in the planting furrow at a certain angle to the ground (10-20 degrees) with the root crown upward and the root tail downward, then covering with soil and pressing firmly. The planting depth is generally advisable with the root crown buried 5-10cm into the soil layer; for autumn transplanting, the soil covering thickness should be appropriately increased, and the soil covering thickness on loamy soil should be slightly shallower than on sandy soil. Transplanting density should be determined according to conditions such as soil fertility. Under site conditions with sufficient sunlight and fertile soil, the planting density is generally a row spacing of 25-30cm and a plant spacing of 10-13cm (which can reach 300,000-320,000 plants/hm2). On arid and barren land, the transplanting density can be appropriately reduced. Under soil drought conditions, after transplanting, sufficient water should be irrigated in time; especially for autumn transplanting, it is necessary to ensure the water balance within the seedlings from transplanting until emergence. In areas east of Chifeng, pathogenic bacteria causing licorice root rot exist in the soil, and before transplanting, a fungicide that does not leave medicinal residue should be used for root dipping treatment.

4. The key technical points for the success or failure of licorice cultivation. Deep plowing before sowing for seedling raising is key, preferably to a depth of 40cm, which is beneficial to licorice root growth and the formation of high-quality transplant seedlings. If the plow layer is relatively shallow, licorice root growth will be hindered, the main root is very likely to fork, and the quality and yield of the product will be affected. Before sowing, sufficient bottom water should be irrigated, and sowing should be carried out when the field water-holding capacity of the soil is about 80%. Sowing for seedling raising should be done in spring when the soil thaws and the temperature of the 5cm soil layer is stable at about 10°C. Seed treatment before sowing is the key technical point for ensuring emergence; lightly grinding 3 times with a rice mill can generally make the germination rate reach above 80%. The soil covering thickness is 2-3cm, and the soil should be pressed after sowing. Selecting high-quality transplant seedlings is the core measure for ensuring high yield and high quality; it is best to select transplant seedlings with a rhizome head diameter above 8mm and a main root length of about 40cm. If root rot fungi are present in the soil of the transplant site, root rot disease is likely to be triggered after transplanting, and before transplanting a fungicide should be used for root dipping treatment. Timely weeding is the key to the success or failure of seedling raising, and also the key to the success or failure of transplanting cultivation.