Key Technical Points for Intercropping Cultivation of Japanese Knotweed (Polygonum cuspidatum) Under Forest Canopy
I. Cultivation Specifications
The specifications are 15cm×40cm, i.e., plant spacing 15cm, row spacing 40cm, with 11,100 plants per mu, using under-forest intercropping to improve comprehensive land benefits.
II. Cultivation Time
Planting time is divided into autumn planting and spring planting. Autumn planting should be carried out in mid-to-late October, and spring planting should be carried out in mid-to-late April.
III. Cultivation Techniques
1. Land preparation: First carry out deep plowing, loosening the soil, clearing weeds, and removing larger stones. Deep plowing and soil loosening should reach 20-25cm or more. Apply 1,500-2,000kg per mu of fully decomposed human and livestock manure or barnyard manure as base fertilizer, and mix it evenly with the soil layer 5-10cm deep. Do not use the method of plowing and turning the land after planting, because only deep plowing and soil loosening before planting can create good conditions for root growth; otherwise, the defects cannot be compensated for. After deep plowing, break up the soil clods finely so that the ground is loose and level.
2. Marking points and digging holes: According to the plant and row spacing of 15cm×40cm, use lime or plant ash to draw lines and mark points for digging holes. The holes should be 10-15cm deep and wide. At the same time, keep the topsoil and subsoil separate.
3. Applying sufficient base fertilizer: Before planting Japanese knotweed, apply decomposed farmyard manure into the dug holes to improve soil fertility, improve soil structure, enhance the soil's water-holding and fertilizer-retaining capacity, and provide good growing conditions for root growth. Apply 1,000-1,500kg of farmyard manure per mu. After applying the base fertilizer, fill in a 3-5cm thick layer of topsoil.
4. Planting: Take 1-2 year old rhizomes with root buds from old roots as planting material. Before transplanting, soak them in 0.5‰ 920 for 5-10 minutes. The length of each planting section should preferably be 10cm. Plant along the bed. When planting, place the planting material at a 30°-45° angle to the edge of the bed, with plant spacing 15cm and row spacing 40cm. Arrange the planting material with root buds in an alternating pattern of one reverse and two upright, so that the plants have more space to grow. After placing the planting material, sprinkle compound fertilizer mainly containing phosphorus and potassium on top, at 20-25kg per mu, then cover with 3-4cm of soil and water thoroughly. After the water seeps through, cover with another 4-5cm of soil, so that the total thickness of the two soil coverings reaches 8-10cm. For autumn planting, it is best to add a covering material, which has a certain protective effect on the planting material. Remove it before greening in spring to increase ground temperature and promote growth.
IV. Field Management
1. Leveling the ground: After digging holes and planting, if the ground appears uneven, level it promptly to facilitate future management.
2. Fertilization: Before Japanese knotweed sprouts in early spring, open shallow furrows between the two rows and bury 2,000 kg/mu of decomposed human and livestock manure or barnyard manure, then water twice in succession. By mid-to-late June, spray 120 kg/mu of 0.5% potassium dihydrogen phosphate solution, and spray again after 10-15 days. Foliar spraying of potassium fertilizer can inhibit excessive stem and leaf growth and promote root swelling, and can increase yield by 20%. When seedlings are 5-8cm tall, loosen the soil and remove weeds. Water during drought. From May to June each year, apply 1,000 kg/mu of human and livestock manure or 1,500 kg/mu of barnyard manure as topdressing, and water after application.
3. Weed control: Once each in March and June every year. Each time, mix 100 kg of water, 1.5 kg of 10% glyphosate aqueous solution, and 0.2 kg of washing powder evenly, then spray on the weeds on a sunny day. Be careful never to spray the liquid onto the stems and leaves of Japanese knotweed. In autumn, before the weeds set seed, remove the “seeding weeds” once to prevent the spread of weed seeds, reduce harm in the following year. After the aboveground part dies back in winter, remove the weeds and cover them on the rhizome surface of Japanese knotweed to prevent the rhizomes from being damaged by excessively low winter temperatures.