Detailed Explanation of Intercropping and Relay Intercropping Models of Chinese Medicinal Herbs and Crops

Intercropping and relay intercropping of crops and Chinese medicinal herbs is a reflection of scientific farming. It can effectively resolve the conflict over land between grain and medicinal herbs, make full use of natural resources such as land, light energy, air, water, fertilizer and heat, and give play to marginal effects and mutually beneficial interactions between plants, so as to achieve a bumper harvest of both grain and medicinal herbs.

1. Intercropping and relay intercropping model on surplus crop field edges. Within a field, the cultivable area is about 70%, while the field edges, ditches, roads and embankments account for about 30%, and in mountainous and hilly areas the proportion is even larger. Using these idle surplus spaces to grow some Chinese medicinal herb varieties with strong adaptability and low soil requirements can effectively use the land and increase income, while also reducing the evaporation of water and nutrients and controlling the disease and insect damage brought to crops by weed growth. For example, for honeysuckle (Lonicera japonica), a Chinese medicinal herb that is tolerant of waterlogging and drought and has low requirements for climate and soil, dig holes along field edges, roadsides and ditch sides at a plant spacing of 80 cm, and plant 6 seedlings around the inside of each hole. Every 667 sq m (1 mu) of surplus field edge can plant about 60 holes, each hole yields about 0.5 kg of commercial flowers per year, the market price is 30 yuan/kg, the annual benefit per hole is 15 yuan, and every 667 sq m of land can increase income by 60×15=900 yuan per year. Medicinal herb varieties suitable for planting on surplus field edges also include: licorice (Glycyrrhiza), cassia seed (Senna obtusifolia), garden balsam seed (Impatiens balsamina), Atractylodes lancea, schisandra (Schisandra chinensis), papaya (Chaenomeles), cowherb seed (Vaccaria hispanica), Polygonatum odoratum, astragalus (Astragalus membranaceus), safflower (Carthamus tinctorius), gentian (Gentiana), rhubarb (Rheum) and so on.

2. Intercropping and relay intercropping model of tall stalks and short stalks. Reasonably matching tall crop stalks with short-growing medicinal herbs, aiming at a three-dimensional composite population, using vertical distribution space, increasing the multiple cropping index, and following the principle that the early crop is for the late crop and the late crop is for the whole year, improves the utilization rate of light energy and land, thereby greatly increasing economic benefits. For example, the isatis (Isatis indigotica)—corn—bupleurum (Bupleurum chinense) "three plantings and two harvests in one year" planting model. In early spring, make high beds 1.5 m wide with water ditches left on both sides on finely plowed and harrowed land. From March to April, sow isatis on the high beds. From May to June, dibble corn in the water ditches at a plant spacing of 60 cm, leaving 2 seedlings per plant, with routine management. In August, when the corn has completed vegetative growth, the isatis can be dug and harvested, and then bupleurum is sown in succession. At this time, the shade of the corn can provide good conditions for the germination of bupleurum, and the bupleurum seedlings can emerge completely in 15-20 days. In September to October, after the corn is harvested, the bupleurum seedlings can grow vigorously. Crop varieties suitable for intercropping in this model also include: corn, sorghum, sugarcane, cotton and other crop types with tall stalks that can provide a shaded environment. Medicinal herb varieties planted in combination include isatis, angelica dahurica (Angelica dahurica), platycodon (Platycodon grandiflorus), chuanxiong (Ligusticum chuanxiong), atractylodes (Atractylodes macrocephala), salvia (Salvia miltiorrhiza), belamcanda (Belamcanda chinensis), coix (Coix lacryma-jobi), bupleurum, pinellia (Pinellia ternata), pseudostellaria (Pseudostellaria heterophylla), coptis (Coptis chinensis), sarcandra (Sarcandra glabra), tsaoko (Amomum tsaoko) and so on, which have shorter growth periods and are shade-tolerant.

3. Intercropping and relay intercropping model of deep-rooted and shallow-rooted types. According to the characteristics and nutrition of plant varieties, reasonably combine them into a population that utilizes resources such as land, light energy, air and heat at multiple levels, so as to increase the thickness of the vertical utilization layer, convert as much input energy and matter as possible into economic products, and achieve the goal of increasing yield and efficiency. For example, interplant cassia seed, atractylodes and so on in watermelon fields. Because watermelon roots are shallow and cannot absorb and use nutrients from deeper soil layers, but their water and fertilizer demand is large while the absorption rate is low, so water and fertilizer and other nutrients must be added artificially. The interplanted Chinese medicinal herbs such as cassia seed and atractylodes reduce nutrient loss by absorbing and using excess nutrients in the surface layer, and can absorb nutrients from deeper soil layers to meet their own growth needs. Crop varieties suitable for this model also include winter melon, pumpkin, sweet potato, potato, soybean and so on, and the Chinese medicinal herb varieties planted in combination include licorice, honeysuckle, astragalus, platycodon, atractylodes, angelica dahurica, safflower, yam (Dioscorea), coix, papaya (Chaenomeles), anemarrhena (Anemarrhena asphodeloides), ginger, saffron (Crocus sativus). The intercropping and relay intercropping methods of Chinese medicinal herbs and crops also include: intercropping between beds, intercropping between rows, intercropping in the middle of beds, intercropping between ridge beds and mixed cropping, etc. No matter which intercropping and relay intercropping method is adopted, attention should be paid to the reasonable matching of large and small plant types, broad leaves and narrow leaves, parallel leaves and upright leaves, long and short growth periods, etc., and to the relationships among light, temperature, water and nutrient conditions among various plants, so as to maintain the geo-authenticity of Chinese medicinal herb varieties.