How to Grow Astragalus? A Detailed Guide to the Latest Standardized Cultivation Techniques
The Chinese medicinal herb astragalus is a leguminous plant, divided into two strains: Astragalus mongholicus and Astragalus membranaceus. It is mainly produced in Inner Mongolia, Shanxi, Gansu, Heilongjiang and other provinces and regions, and is a national third-class protected plant. Astragalus has the effects of tonifying qi and stabilizing the exterior, promoting diuresis and reducing swelling, expelling toxins and discharging pus, and promoting tissue regeneration. Astragalus has a medicinal history of more than 2000 years. Modern research shows that astragalus contains saponins, sucrose, polysaccharides, various amino acids, folic acid, and various trace elements such as selenium, zinc and copper. It has the effects of enhancing human immune function, protecting the liver, promoting diuresis, anti-aging, anti-stress, lowering blood pressure, and a relatively broad antibacterial effect. Astragalus is drought-tolerant and cold-resistant, highly adaptable, and stable in yield, making it suitable for standardized cultivation in arid and semi-arid regions.
Site Selection and Deep Plowing
Astragalus is a deep-rooted plant. The planting site should be chosen as neutral or slightly acidic sandy soil with deep soil layers, loose and fertile texture, good drainage, and high, dry, sunny terrain. Flat land, hills, and mountain slopes can all be used for planting. Sites with a high groundwater table, high soil moisture, heavy clay texture, low-lying waterlogged clay, or poor gravelly soil are not suitable for growing astragalus. After selecting the plot, deep plowing should be carried out to improve the soil. After the autumn crops are harvested, plow the soil deeper than 30 cm to break through the plow pan; before plowing, remove weeds, stones and debris from the field. According to years of planting experience at the base of the Heze City Runkang Chinese Medicinal Materials Research Institute in Shandong, deep plowing can thicken the active soil layer, mature the soil, enhance the soil's water storage and moisture conservation capacity, improve soil aeration, promote microbial activity, accelerate the decomposition of organic nutrients, increase soil fertility, benefit root growth, and reduce the formation of lateral roots and "chicken-claw astragalus." It is an effective measure for obtaining high-quality and high-yield astragalus.
Pre-Sowing Preparation
Before sowing, on the already deep-plowed soil, broadcast 3000 kg of farmyard manure or pen manure per mu. According to the soil pH value, apply 100 kg of superphosphate or calcium magnesium phosphate fertilizer and 30 kg of high-quality diammonium per mu; then rotary till twice, level and harrow fine, and then make high beds or ridges. The bed height is 25 cm, the width is 1.2 m, the ditch width is 40 cm, and the bed surface is shaped like a turtle shell, with drainage ditches opened around it. High-bed cultivation not only thickens and loosens the tillage layer and provides good drainage, but also absorbs and releases heat quickly, with a large diurnal temperature difference, which is beneficial to astragalus root development and nutrient accumulation.
Cultivation Techniques
1. Selecting good seed: "Using good seed" is something everyone knows is important, but it is very difficult to buy good seed of the Chinese medicinal herb astragalus on the market. At present, for artificially cultivated astragalus, whether by farmers or so-called bases (except for self-bred seed used by their own bases), most of the seeds used for sowing have not been bred. Year after year of planting has caused serious degeneration, poor disease resistance, and declining yields year by year, seriously affecting quality. When medicinal farmers grow astragalus, first, they harvest the roots and stems as medicinal material, and second, they can also earn a considerable income by selling the seeds. Therefore, most astragalus seeds on the market are naturally harvested from astragalus grown in open fields. In addition, people who buy seeds lack technical knowledge and only focus on the price and germination rate of the seeds, not on seed germination vigor, and they do not know what good seed is; therefore, even if there is bred seed, it cannot sell for a high price. The Heze City Runkang Chinese Medicinal Materials Research Institute in Shandong suggests that medicinal farmers, when selecting and breeding excellent astragalus seed, should choose plants in 2-3 year old astragalus fields that are consistent in seed traits, strong in growth vigor, disease-free, non-degenerated, and with short internodes, mark them, adopt the "family planning" measures of removing the top and thinning flowers, manage them separately, and harvest and store them separately, so that they can be used as seed for "GAP" standardized cultivation of astragalus.
2. Sowing techniques: Sowing should seize the soil moisture. If the soil moisture is poor, water the bottom soil moisture well.
(1) Sowing time: Astragalus can be sown in spring, summer and autumn. According to the planting experience of the Heze City Runkang Chinese Medicinal Materials Research Institute in Shandong, in the Huang-Huai region, spring sowing of astragalus should be carried out around "Qingming," no later than "Guyu," keeping the soil moist, and seedlings will emerge in about 15 days; summer sowing is carried out from June to July, and seedlings emerge in 7-8 days after sowing; autumn sowing is generally carried out around "Bailu." Due to different climate conditions in different places, sowing times vary and should be flexibly controlled. Regardless of the region, spring sowing must only be done after the soil temperature is stably above 12 degrees (with plastic film mulching). Summer sowing should be early rather than late, and sun protection after seedling emergence should be done well. For autumn sowing, because the temperature in the Huang-Huai region is high, sowing can be done in September, with seedlings emerging before winter; in the cold regions of Northeast and Northwest China, sowing should be done before the soil freezes, with seedlings emerging in spring.
(2) Sowing methods: Generally, hole sowing and drill sowing are used. For hole sowing, open shallow holes on the prepared bed surface at a row spacing of 30 cm × 25 cm, sow 6-7 seeds per hole, cover with soil 2 cm thick, and use 1-1.5 kg of seed per mu. For drill sowing, open horizontal furrows on the bed surface at a row spacing of 40 cm, with a furrow depth of 3 cm. When sowing, mix the seeds evenly with plant ash and organic fertilizer, then evenly scatter them into the furrow, cover with fine soil 1-2 cm after sowing, and press lightly; in recent years, when the Heze City Runkang Chinese Medicinal Materials Research Institute has planted large-scale bases, it has used a seeder to complete furrow opening, sowing, soil covering, and pressing in one pass with treated good astragalus seed, which can effectively reduce labor and improve sowing quality, using 2 kg of seed per mu.
Field Management
1. Seedling management: After astragalus seedlings emerge completely, thinning should be carried out in time to avoid crowding, mutual shading, and competition for fertilizer and water; when thinning, remove crowded seedlings, clumped seedlings, and weak seedlings. When the seedlings are 10-12 cm tall, final thinning should be carried out. For hole sowing, keep 2-3 strong seedlings per hole; for drill sowing, keep 1 strong seedling every 10-12 cm according to plant spacing. During final thinning, if there are missing seedlings, the large seedlings removed can be transplanted to fill the gaps. Transplanting should be done on cloudy days or in the afternoon or evening of sunny days, and watered after planting.
2. Cultivation and weeding: Astragalus seedlings grow slowly, and after emergence, weeds and seedlings often grow together. If not paid attention to, it can easily cause weed infestation, so weeding should be done in time. Weeding work should be combined with cultivation. Cultivation can loosen the soil, cut off soil capillaries, prevent water evaporation, and play a role in drought prevention and moisture conservation; after heavy rain and prolonged rain, cultivation also plays a role in draining moisture and preventing waterlogging; when the seedlings are 7-8 cm tall, carry out the first cultivation, and after final thinning, carry out the second cultivation. The depth of cultivation is generally carried out according to the principle of shallow during the seedling stage, deep for mature plants, shallow near the seedlings, and deep between the rows, so as not to injure the seedlings, bury the seedlings, damage the roots, or leave weeds. After the second year, cultivate once each in April, June and September. According to the planting experience of the Heze City Runkang Chinese Medicinal Materials Research Institute in Shandong, combined with the requirements of "GAP" standardized production, during the young stage when there are many weeds, a special herbicide for astragalus can be sprayed once (herbicide can only be used once per year), basically ensuring no weeds in the field.
3. Fertilizer and water management: In order to meet the nutrient needs of different growth periods and increase yield, in the current year and the second year of growth, topdressing is applied twice each year in combination with cultivation and weeding. The first topdressing is carried out in combination with the second cultivation and weeding. Mix 1500 kg of compost, 50 kg of superphosphate, and 10 kg of ammonium sulfate evenly per mu, then open furrows between the rows and apply, covering with soil after application. The second time, after the seedlings wither in winter, mix 2000 kg of barnyard manure, 50 kg of superphosphate, and 150 kg of cake fertilizer evenly per mu and apply to the field, then earth up after application to prevent freezing. Astragalus consumes little water at the seedling stage. In order to promote downward root growth, increase root length, and improve astragalus yield, under the condition of sufficient soil moisture at sowing, watering may be omitted. If the bottom soil moisture is insufficient and the weather is dry, use small water or alternate-row irrigation, and never flood irrigate. During the seed-setting and ripening stage, if there is high temperature and drought, watering should also be done in time to promote normal seed maturation, reduce the hard seed rate, and improve seed quality. If soil moisture is too high during the rainy season, it will cause root rot. Plots prone to water accumulation should be drained in time to reduce soil moisture, so as to facilitate normal root growth.
Harvesting and Processing
1. Harvest time: According to the planting experience of various technical guidance bases of the Heze City Runkang Chinese Medicinal Materials Research Institute in Shandong, the growth years of astragalus in different regions are: in the Huang-Huai region, harvest after 1-2 years of growth; in the Northwest and Northeast regions, harvest after 2-3 years of growth. If harvested too early, the quality of astragalus is poor; if not harvested for a long time, it is very easy to become black-hearted or lignified. The harvest time is generally in autumn when the plants wither, or before germination in the following spring, because at that time the roots are fully grown and the content of accumulated active ingredients is high, giving high astragalus yield. When harvesting, dig deep, do not injure the roots, and prevent breaking the main root, which would affect the yield and quality of the medicinal material. For large-scale planting bases, before harvesting, cut off the aboveground stems, then use an astragalus harvester for one-pass harvesting.
2. Processing at the production site: After the astragalus roots are dug out, remove the stems and leaves attached to the roots, shake off the soil, cut off the rhizome head while fresh, trim off the fibrous roots, and then dry them in the sun. When they are 60-70% dry, straighten the roots, tie them into small bundles, and sun-dry until completely dry. When drying, avoid strong direct sunlight; place them in a ventilated place, spread a layer of white paper on top, and sun-dry until completely dry or dry them in a heated drying bed. Astragalus medicinal material is considered best when the root strips are thick and strong, straight, hard in texture, full of powder, and sweet in taste. It is required to be dry, without rhizome heads, without fibrous roots, not moldy, not scorched, free of mud, and free of impurities.