1 Natural Fertility Characteristics of Site Selection and Soil Preparation 1. 1 The biggest feature of semi-wild Astragalus cultivation is that it relies on natural fertility to meet the demand for soil nutrients for the growth and development of Astragalus, which is the biggest difference from the method of artificially cultivating Astragalus in farmland. Astragalus membranaceus cultivated in farmland mainly relies on artificial fertilization to meet the demand of Astragalus membranaceus for nutrient elements, including farmyard manure and chemical fertilizer. When applying farmyard manure, it is often impossible to kill all harmful bacteria and eggs in the retting process. Most of them are farmyard manure, which is not cooked or semi-decomposed. These bacteria and eggs will be harmed during the growth of Astragalus membranaceus. In order to control pests and diseases, chemical control was adopted, which greatly increased pesticide residues and soil heavy metal pollution. Semi-wild cultivation relies entirely on natural fertility. Because it is far from the village, the mountain is high and steep, and the path is narrow, it is impossible to transport a lot of farmyard manure into the cultivation land. Reclaim wasteland, cultivate Astragalus once (3-5 years), then abandon cultivation for 5-6 years, rely on natural vegetation to restore soil fertility, cultivate again twice, and then abandon cultivation in turn. The natural fertility characteristics of this method are pure natural, green, pollution-free and high quality. 1.2 The location is more than 3km away from the village, and there is no pollution source around. The atmosphere meets the national GAP quality standard. Select the hillside where the distribution population of wild Astragalus is concentrated. Generally, the slope of cultivated land should be15 ~ 35. It is not advisable to choose gentle slopes or hillside terraces with low slopes. Because of poor drainage in rainy season and poor soil ventilation and water permeability, Astragalus membranaceus is suitable for root rot in its growth period. The soil layer with large slope is shallow, the natural fertility is insufficient, and the manual operation is unsafe, so it is not suitable for selection. The slope strike from northeast to southwest should be semi-cloudy, semi-sunny or partially sunny; The east-west south slope is pure sunny slope, with scarce vegetation and insufficient soil fertility; Although the pure shady slope on the north slope has good fertility and vegetation conditions, the planting of Astragalus membranaceus is easily affected by pests and diseases, and the product quality is also poor. The wasteland vegetation mainly includes hazelnut, Spiraea, Hippophae rhamnoides and Huang Qiangwei. And herbs such as Artemisia scoparia, Artemisia scoparia, Artemisia scoparia, Artemisia annua, Artemisia argyi, etc. Soil fertility is high. However, perennial gramineous plants, such as imperata, reed and so on, have low fertility, so it is necessary to rake out all the underground roots of perennial plants and clean up the cultivation area during soil preparation, otherwise the cultivated Astragalus will be short of grass, and it is difficult to control or increase the production cost. Loam, sandy loam and gravel soil are suitable for the soil, and the thickness of humus in the surface soil is above 10 ~ 15 cm. Theoretical basis of selecting land without applying chemical fertilizer. It is very important to select the site for producing green and pollution-free genuine astragalus. The soil in the breeding ground must be free from heavy metal pollution, and pollutants such as pesticides and fertilizers shall not be used in the breeding process to prevent the concentration of toxic substances in the food chain. Once the toxic substances enter the cultivation system, they will immediately participate in the material cycle, and the toxic substances with stable properties and easy absorption by organisms (Astragalus membranaceus) will be enriched and concentrated step by step along the food chain. Food chain concentration, also known as biomagnification, refers to the phenomenon that the residual concentration of toxic substances in organisms increases continuously when they pass along the trophic level of the food chain. The higher the trophic level, the higher the residual concentration of toxic substances in organisms. According to the experiment of South China Agricultural College in Qujiang County, BHC powder used 20 days before rice harvest and rice treated for 2 ~ 3 times as feed for pigs and chickens, the enrichment multiple of BHC in eggs is 12 ~ 26 times that of rice. The enrichment multiple of bhc in pig fat is as high as 38 ~ 75 times. Mercury, cadmium, lead, chromium and arsenic in heavy metals are toxic, which are called five poisons, among which mercury is the most toxic, followed by cadmium. Phosphate fertilizer contains not only heavy metal elements, but also metals such as fluorine, radioactive uranium and thorium. The fluorine content of phosphate rock and superphosphate is generally 2% ~ 4%. When the fluorine content in mulberry leaves reaches 10% ~ 15%/kg, young silkworms can be killed. When the cadmium content in soil reaches 20 mg/kg, the growth of wheat is affected. When the cadmium content reached 725 mg/kg, the growth of rice began to be affected. Excessive use of chemical nitrogen fertilizer makes vegetables and other plants accumulate too much nitrate, and nitrosamines generated under certain conditions are carcinogenic and teratogenic substances. 1.3 Soil preparation and contour line "biological isolation belt": semi-wild Astragalus cultivation method belongs to ecologically fragile area because it is carried out in the arid and semi-arid Hengshan area, and the combination of soil erosion, ecological environment restoration and management should be fully considered during cultivation. Before soil preparation, according to the topography, slope and vegetation in the horizontal direction of the contour line, a certain distance of biological isolation belt and farming belt shall be set aside. The bandwidth of biological isolation is generally 2~3 meters, that is, the vegetation in the natural state is preserved, and the natural ecological function of isolation belt is used to prevent soil erosion. Water conservation is fertilizer conservation, and soil conservation is also fertilizer conservation. If the slope is large, more isolation belts should be left, and if the slope is small, the cultivation belts can be appropriately increased, so that the belts can be left according to the place and mastered flexibly. It is forbidden to burn wasteland when preparing soil. Fire zone will reduce soil fertility, cause mountain fires, and burn the biological isolation zone, which will not play the role of isolation zone. "Biological isolation belt" is one of the most important characteristics of this cultivation method. Eco-economic benefits: Hunyuan has 330,000 mu of Huangqi sloping land, with an average annual purchase volume of 6.5438+0.5 million kg and the longest purchase volume of 6.5438+0.5 million kg. If 50,000 mu is cultivated in this way, Astragalus membranaceus will be harvested after 5 years of growth. According to the annual harvest 1 10,000 mu, the yield per mu will be 500 kg, with an average annual total yield of 5 million kg, which is 3 million kg higher than the maximum wild purchase. That is, a small amount of land can not only effectively protect a large area of wild Astragalus resources, but also protect the ecological environment in Hengshan area, and supply high-quality Astragalus to the market, benefiting many parties. Soil preparation according to contour lines: after the biological isolation belt is drawn according to contour lines, soil preparation will be started from bottom to top, the turned soil ridges will be broken, the grass roots and shrub roots will be picked out, and the cultivation belt will be removed, or it will be put on the edge of the isolation belt to die in the sun. There are many stones on the steep slope and the soil layer is thin. Arranging excavated stones into stone weirs with equal height, or building stone weirs on biological weirs, or biological isolation belts, cultivation belts and artificial stone engineering weirs are more conducive to soil and water conservation. When preparing soil on steep slope above 28℃, due to the large slope and thin soil layer, in order to thicken the active soil layer, the "active soil double-layer method" can be adopted. That is, first make a cultivation belt with a width of 2-4 meters on the biological isolation belt or the stone weir, then make a cultivation belt with the same width, and cover the first cultivation belt with its living soil to double the living soil layer. Then build stone weirs on the dead soil layer in turn. The loose and porous soil in the active soil layer is beneficial to the root system of Astragalus membranaceus, and the rainy season is beneficial to the rapid infiltration of rainwater, which can effectively prevent soil erosion. The soil in the raw soil area is dense, which can intercept the water infiltrating into the raw soil area, prevent the soil moisture from falling down the slope, and make more natural precipitation in rainy season effectively stored in the isolated soil.
2. Determination of sowing date 2. 1. Soil preparation for summer sowing or autumn sowing should be carried out in the early spring of the following year, generally after the soil is thawed in late April, the sooner the better, and should be completed before May 10 at the latest. It is good to broadcast seedlings early, because the soil was prepared last year, and the soil has matured and collapsed in one winter. The soil has good physical and chemical properties, which is very beneficial to the growth of Astragalus. The root system of Astragalus membranaceus is thick and long before overwintering, generally more than 30 cm, some as long as 60 cm, or longer, with many single roots, few branches and good commercialization. The growth of Astragalus membranaceus in the first year is very important for the growth in the future, and the strong seedlings first strengthen the roots. Early sowing should be strongly advocated in production, because this method is cultivated on the hillside and it is impossible to irrigate. The soil moisture content of early sowing is good, which can meet the water demand of seed emergence. With the passage of time, the turn of spring and summer in Hengshan area is a windy season, and the evaporation of soil moisture increases with the increase of wind. The later the sowing date, the more unfavorable it is for seedling emergence. When land is reclaimed in spring, the sowing time depends on the weather. Soil preparation in spring can not be sown early, because the living soil layer is loose and the soil moisture is not enough, so it is difficult to produce a whole seedling after sowing, which is suitable for "hanging roots" to make the seedling die. When to sow? Sow before the rainy season, or sow after the next soaking rain. Compared with spring sowing, the seedlings of Astragalus membranaceus planted in summer grew poorly and failed to form strong seedlings. Because the seeds of Astragalus membranaceus are not conducive to seedling emergence at high temperature, the root system is thin and short during wintering. Autumn sowing is generally not recommended, because autumn seedlings are not conducive to overwintering, and they are small seedlings. After the emergence of seedlings in the second year, the taproots are easy to branch and form small old seedlings, that is, "small old seedlings", which are characterized by malnutrition and no resistance to pests and diseases. 2.2 Seed Source Hengshan Astragalus membranaceus is a unique germplasm resource of Chinese herbal medicine. Collecting wild Astragalus seeds in situ, the local germplasm itself has a variety of stress resistance, which is also the basic condition to ensure quality. It is an inseparable organic whole consistent with environmental conditions. Generally, seeds with vigorous growth, strong pest resistance and basically the same seed maturity are collected from late July to early August in the local area. Sun-dried and threshed, stored in a ventilated and cool place, and used next year. Or select the micro-sunny slope and sunny slope in the field to establish a wild seed production base, and select excellent seed roots through transplanting technology to harvest 2-year-old seeds. 3-year-old seeds have the best quality, vigorous growth and strong resistance, and plants after 4 years are generally not suitable for selection. The 3rd and 4th years are the most vigorous growth period of Astragalus membranaceus. From the 4th year, its vitality gradually declined, although it can grow continuously 10. The use of wild seeds is another feature of this method. 2.3 Seed treatment Before sowing, take out the seeds, mix them with coarse river sand according to the ratio of 3_ 1, and roll them quickly on the stone mill for several times. The seed thickness is generally 1.5 ~ 2.0 cm, the seed changes from dark brown to grayish brown, and the seed coat is hairy. After grasping them by hand, the fine dust falling off the seed coat adheres to the skin, and it is appropriate for the seed coat to be slightly scratched by the stone mill. Over-rolling, seeds will be damaged without germination, over-rolling, and seed germination rate is not high, so it is necessary to master moderate rolling. Then use 500 times of carbendazim bactericide 10 minute to sterilize, take it out and drain the water on the surface of the seeds, soak the seeds with 1000 times of phoxim 10 minute to kill the eggs, take it out and dry it, or drain the water on the surface of the seeds to sow. 2.4 The method of sowing is completely different from that of cultivating Astragalus membranaceus in farmland. Because it is planted on the hillside, the mountain is high and steep, so it is impossible to use mechanical sowing or livestock sowing, and it is completely artificial sowing. Using artificial ditching sowing method, ditching according to contour line, and the slope is from bottom to top. If the slope exceeds 28, it should be from top to bottom. Otherwise, after sowing, the soil on the last ridge will naturally fall, which will deepen the covering of the next ridge and make it difficult for seeds to emerge. Because dicotyledonous plants are weak in covering soil when they emerge, seeds should not be covered too deeply. Remove the plow wall (mirror surface) with a hoe, a hoe or a double hook hoe, or use a wooden plow, leaving only the share, and open a shallow ditch with a width of10cm and a depth of 3-4cm, with a row spacing of 40-50cm, and sow evenly, with an area of 2.0-3.0kg per mu. Cover the soil with seeds, covering 2 cm, and then tie a small bundle of shrubs to mop the floor, that is, the proper depth of seed covering the soil. After soaking seeds, make good use of soil water content to accelerate the germination and emergence of seeds; If the soil moisture is poor, use dry seeds. After sowing, step on the seeds along the ditch with your feet, and then drag the bushes to cover the seeds. Sowing with dry seeds with poor soil moisture is called "wet out of dry seeds" locally, that is, waiting for rain to appear. You can also sow after the next soaking rain, and the effect is better. The emergence of seedlings after spring sowing is about 65438 05 days, and that after summer sowing is about 7 days.
3. Field management 3. 1 Growth characteristics As Astragalus membranaceus is a deep-rooted plant, it has gradually gained drought resistance in long-term biological evolution, and it is a drought-resistant plant population in this area, and its drought resistance is second only to Casuarina sinica, and Astragalus membranaceus has become the dominant species of herbs in this area. The method of imitating wild cultivation or semi-wild cultivation is different from natural conditions. First of all, the growth environment is basically the same, which is one of the most important characteristics of this law. Try to create an environment that is the same as the wild conditions for Astragalus membranaceus, or the basic environment of the great cycle is the same. The application of "biological isolation belt" is that the small environment is as same as possible. The cultivation areas are basically different. Astragalus membranaceus growing in the belt only has intraspecific competition, but there is no interspecific competition among different biological species, so its competitiveness is greatly reduced and its growth environment is superior. But it is different from the method of planting astragalus in farmland. 3.2 intertillage weeding Astragalus membranaceus planted in spring or summer is the seedling growth period from emergence to overwintering, and basically does not bloom 1 year, which is a pure vegetative growth period and the most important growth period of Astragalus membranaceus in its life. It is characterized by slow growth, especially the growth of aboveground stems and leaves, while the growth of underground roots is relatively fast, which is characterized by long roots. The main management task of seedling stage is to prevent grass shortage, especially the early management after emergence. Because it is produced in newly reclaimed wasteland or abandoned wasteland for many years, there are more weed seeds scattered in the soil than in farmland soil, so it is relatively easy to control annual weeds, especially perennial weeds, such as imperata, reed and so on. Its underground rhizome grows fast, and after the above-ground part is pulled out, the underground rhizome will sprout again soon. This weed is very harmful to the growth of astragalus seedlings. Weeds will spread at an alarming rate if they are not completely removed during soil preparation. If it is not controlled in time, it will become the dominant species in the ecological community. Astragalus seedlings are always at a disadvantage. Water and nutrients can't compete with weeds, but if they are not supplied in time, the seedlings will grow thin and vulnerable to pests and diseases, which will eventually lead to death. Weeding at seedling stage should master the principles of early weeding, small weeding and large weeding, and it is difficult to weed once it is grown. Generally, weeding twice at seedling stage can prevent the harm of weeds, or it is more beneficial to the growth of Astragalus membranaceus combined with intertillage and loosening soil. The roots of Astragalus membranaceus germinate when the ground temperature reaches 5℃ ~ 8℃ every year, and are gradually unearthed above 10℃. They began to turn green in May 1 day, and then grew rapidly, reaching the normal plant height in about 30 days (June 1 day), and then the growth rate slowed down. The weeding task of astragalus perennial roots is mainly carried out before the closure of the line, that is, before the first ten days of June, and one month after the emergence of seedlings is the most critical. Weeding is not a big task after closing the line, just pull out the grass in the outcrop to prevent the harm caused by weed sowing next year. The field management task of imitation wild cultivation method is mainly weeding, because it emphasizes nature, green, pollution-free and high quality, and basically does not use other chemical methods such as topdressing. 3.3 The general principle of pest control is not to use chemical methods under normal circumstances. This law emphasizes nature, pollution-free and green. If it happens, some biological fungicides or biological insecticides can be sprayed properly, or ladybugs, mosquitoes and flies, Trichogramma and so on can be cultivated to achieve the purpose of biological control with insects. The method is carried out in the distribution center of wild Astragalus membranaceus in Hengshan Mountain, and only a small area is cultivated. The surrounding environment is basically the original ecological condition, and the ecological balance between animals and plants is always a balanced relationship of interaction and mutual restriction. In addition, because it is cultivated on the hillside, the mountain is high and steep, which has natural advantages that farmland soil conditions do not have, that is, good ventilation and light transmission conditions, vigorous growth of astragalus plants and strong resistance to pests and diseases. The use of pesticides will also upset this balance and kill beneficial organisms in the process of use. After years of planting, no serious pests and diseases have occurred.
4.4. 1 Determination of harvest time. Through experiments, the 1 year-old astragalus cultivated by this method can not be harvested, and the root yield is very low or basically absent, and the root moisture content is high and the dry rate is not high, which can not meet the requirements of commercialization. The yield of 2-year-old is also very low. Generally, the yield of fresh products per mu is only 300 kg, and the dry rate is 30%, which is not suitable for harvesting. Rooting in three years is more than 50 cm long, generally 60~70 cm, and the yield of fresh products per mu is 500 kg, with a dry rate of 25%, which can be harvested, but the yield can not reach the highest value and the product quality is not the best; The yield and quality of 4~5 years old are the best, and the fresh products can reach more than 1000 kg. 4.2 When excavating and harvesting, according to the contour line and horizontal line, dig a deep ditch from the bottom of the biological isolation belt or the stone weir. Because the excavation is carried out on the slope, the soil layer below 60 cm can generally be dug deep, and the steeper the slope, the deeper the excavation. Generally, Astragalus membranaceus over 4 years old can grow to more than 100 cm, and some of them can grow to more than 150 cm. When you reach 60 cm, it is even harder to dig down. You can tie the root system with hemp rope and try to tie it close to the soil layer. Put a lasso on the knot. Thick astragalus can be carried by two people with a pole, and thin roots can be squatted down by one person. This can not only make the root system of Astragalus membranaceus as complete as possible, but also avoid cutting roots and leaving them in the soil to cause waste and achieve high yield. 4.3 Finishing the whole belt for cultivation and tillage: When Astragalus membranaceus is excavated, the whole belt should be excavated at the same time, so as to do the whole belt work well in advance for the next cycle. Because Astragalus membranaceus is a deep-rooted plant, the excavation depth is more than 60 cm. Compared with reclamation, land reclamation is only the turning of the living soil layer, which basically does not disturb the dead soil layer, while the vertical disturbance to the soil is great during excavation, which greatly destroys the natural structure of the soil, but this destruction has a double-layer effect: first, it is beneficial to thicken the living soil layer, which is very beneficial to the growth of Astragalus in the next rotation cycle; On the contrary, the fertility of the surface soil decreases and the natural structure is destroyed, so it is necessary to bring it back. The original stone weir isolation belt was destroyed in the process of excavation, so it is necessary to rearrange the stone weir isolation belt after excavation, otherwise the slope of the cultivation belt is large, which will increase soil erosion in the cultivation area. After the planting belt is straightened, it is impossible to plant Astragalus membranaceus. If there are many problems in continuous cropping, soil fertility is insufficient and diseases and insect pests are serious, it will take 5-6 years to replant Astragalus. During this period, the soil fertility will be restored by the growth of natural vegetation, and the nutrient balance of the cultivation zone will be restored by the biological groups in the natural ecology, thus developing in the natural direction. Combination of excavation and newly reclaimed biological isolation belt: excavation is carried out according to contour lines, and it will be reclaimed when it reaches the biological isolation belt, which will become the next year's Astragalus cultivation land, that is, the belt isolation cultivation method, and the harvested Astragalus will be abandoned and become a new biological isolation belt. However, the biomass of this isolation belt is small at 1 year, and its ecological function is far less than that of the original natural isolation belt, or it can be used on land with a slope below 20 degrees, but it is not suitable for large slopes.