How to grow the medicinal herb banlangen (Isatis indigotica)? Detailed explanation of cultivation techniques
Site selection and land preparation
Choose a flat site with convenient irrigation and loose sandy loam soil containing more humus. Sites that are too high or too low, soil that is too sandy, and newly leveled land are all unsuitable. After selecting the site, plow deeply, break up the soil, and apply sufficient base fertilizer (mainly organic fertilizer, which can be mixed with some river mud, or add decomposed cake fertilizer), then make beds about 240 cm wide. The bed surface should be shaped like a turtle's back. Open the bed ditches and surrounding ditches so that all ditches connect, and provide drainage outlets.
Planting methods
1. Seed cultivation Roots harvested in the same year do not produce seeds, so seeds should be cultivated separately. When digging and harvesting banlangen, select roots that are straight, thick, unbranched, and healthy without pests or diseases, and transplant them at a spacing of 30×40 cm into fertile seed-production fields, watering promptly. In late November, spread a thin layer of soil-and-manure fertilizer to protect against cold. When growth resumes in the following spring, water and loosen the soil. When the seedlings are 6-7 cm tall, apply topdressing and water to promote vigorous growth. When bolting and flowering begin, apply topdressing once more to make the seeds plump. After the seeds mature, harvest them in batches, dry them promptly after harvest, and store them properly.
2. Seed treatment Before sowing, soak the seeds in 30℃ warm water for 3-4 hours, remove the seeds, let them dry slightly, and mix them evenly with an appropriate amount of dry fine soil to facilitate sowing.
3. Sowing There are two types: spring sowing and summer sowing. Spring sowing is carried out between Qingming and Guyu, and summer sowing between Mangzhong and Xiazhi. Spring-sown products are of better quality. Sowing method: drilling or broadcasting may be used, but drilling is more common. On the prepared bed surface, open wide furrows for sowing, with row spacing of 18-20 cm and sowing width of 4-5 cm. After sowing, cover with soil, press lightly, and water. The sowing rate is 1.5-2 kg per mu, and seedlings generally emerge in 5-10 days.
Field management
1. Thinning and weeding Thin the seedlings about 10 days after emergence, which can be combined with loosening the soil. When the seedlings are 5-10 cm tall, final thinning can be done in a triangular arrangement with a plant spacing of about 6 cm. If water and fertilizer are sufficient, they may be somewhat denser. Weed frequently.
2. Topdressing During the growth of woad (Isatis indigotica), the leaves (daqingye) are cut twice successively. The plants require a large amount of fertilizer for growth. In addition to applying sufficient base fertilizer at sowing, apply topdressing promptly after each leaf harvest, and apply manure fertilizer once more in mid-August to promote root growth.
3. Irrigation and drainage After final thinning, if the weather is dry, irrigate in combination with topdressing, and especially irrigate after leaf harvesting. During the rainy season, clear the ditches and manage soil moisture in time to avoid water accumulation in the field and root rot.