Detailed Explanation of the Key Technical Points for Standardized Cultivation of Astragalus

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 consolidating the exterior, promoting diuresis and reducing swelling, expelling toxins and discharging pus, and promoting tissue regeneration. The medicinal use of astragalus has a history of more than 2000 years. Modern research shows that astragalus contains saponins, sucrose, polysaccharides, multiple 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 relatively broad antibacterial action. Astragalus is drought-resistant and cold-resistant, highly adaptable, and stable in yield, making it suitable for standardized cultivation in arid and semi-arid regions.

I. Site Selection and Deep Plowing

Astragalus is a deep-rooted plant. The planting site should be selected 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, compact and sticky texture, or low-lying, easily waterlogged clay or barren gravelly soil are all unsuitable for cultivating astragalus. After selecting the plot, deep plowing and soil improvement should be carried out. After the autumn crops are harvested, plow the soil to a depth of more than 30 cm to break through the plow pan; before plowing, remove field weeds, stones and debris. According to many years of planting experience at the base of the Heze City Runkang Traditional Chinese Medicine Research Institute in Shandong, deep plowing can thicken the active soil layer, mature the soil, enhance the soil's water storage and moisture retention 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.

II. Pre-Sowing Preparation

Before sowing, on the already deeply plowed soil, broadcast 3000 kg of farmyard manure or barnyard 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 finely, and then make high beds or ridges. The bed height is 25 cm, width 1.2 m, ditch width 40 cm, and the bed surface is shaped into a turtle-back form, with drainage ditches opened well around the perimeter. High-bed cultivation not only thickens and loosens the plow layer and provides good drainage, but also absorbs and releases heat quickly, with a large day-night temperature difference, which is beneficial to astragalus root development and nutrient accumulation.

III. Planting Techniques

1. Selecting good seeds: "Selecting good seeds" is something everyone knows is important, but for the Chinese medicinal herb astragalus, it is very difficult to buy good seeds on the market. At present, whether by farmers or so-called bases (except for seeds bred by their own bases), most of the seeds used for sowing artificially cultivated astragalus have not been bred, and 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 harvest seeds to sell, which also brings in considerable income. Therefore, most astragalus seeds on the market are naturally harvested from astragalus grown in open fields. In addition, buyers of 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 seeds are; therefore, even if there are bred seeds, they cannot sell at a high price. The Heze City Runkang Traditional Chinese Medicine Research Institute in Shandong suggests that when selecting and breeding excellent astragalus seeds, medicinal farmers should, in 2-3 year old astragalus fields, select individual plants with consistent seed characteristics, strong growth vigor, no disease, no degeneration, and short internodes, mark them, adopt "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 seeds for "GAP" standardized cultivation of astragalus.

2. Sowing techniques: Sowing should seize the soil moisture. If the moisture condition is poor, water the base soil well.

(1) Sowing time: Astragalus can be sown in spring, summer and autumn. According to the planting experience of the Heze City Runkang Traditional Chinese Medicine Research Institute in Shandong, spring sowing of astragalus in the Huang-Huai region should be carried out around "Qingming," no later than "Guyu." Keep the soil moist, and seedlings will emerge in about 15 days; summer sowing is carried out from June to July, and seedlings emerge 7-8 days after sowing; autumn sowing is generally carried out around "Bailu." Sowing times differ with climate conditions in different places and should be flexibly controlled. Regardless of the region, spring sowing can only be carried out after the soil temperature is stably above 12 degrees (with plastic film mulching). Summer sowing should be earlier rather than later, and work to protect seedlings from sun exposure after emergence must be done well. For autumn sowing, because temperatures are high in the Huang-Huai region, 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 x 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 trenches on the bed surface at a row spacing of 40 cm, with a trench depth of 3 cm. When sowing, mix the seeds evenly with plant ash and organic fertilizer, then evenly scatter them into the trench, cover with fine soil 1-2 cm after sowing, and press lightly; in recent years, when large-scale bases of the Heze City Runkang Traditional Chinese Medicine Research Institute in Shandong have planted, they used treated good astragalus seeds and a seeder to complete trenching, sowing, soil covering and compacting in one pass, which can effectively reduce labor and improve sowing quality, using 2 kg of seed per mu.

IV. Field Management

1. Seedling management: After astragalus seedlings have all emerged, thinning should be carried out promptly 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. Replanting should be done on cloudy days or in the afternoon or evening of sunny days, and watered after planting.

2. Intertillage and weeding: Astragalus seedlings grow slowly, and after emergence weeds and seedlings often grow together. If not paid attention to, this can easily cause weed infestation, so weeding should be done promptly. Weeding work should be combined with intertillage. Intertillage 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, intertillage also plays a role in dispersing moisture and draining waterlogging; carry out the first intertillage when seedlings are 7-8 cm tall, and the second intertillage after final thinning. The depth of intertillage 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 seedlings, bury seedlings, damage roots, or leave weeds. After the second year, carry out intertillage once each in April, June and September. According to the planting experience of the Heze City Runkang Traditional Chinese Medicine Research Institute in Shandong, combined with the requirements of "GAP" standardized production, during the young stage when weeds are abundant, a special astragalus herbicide can be sprayed once (herbicides can only be used once per year), basically ensuring no weeds in the field.