What are the key points of high-yield cultivation techniques for oil tea?
Oil tea (Latin name Camellia oleifera Abel.), also known as tea seed tree, tea oil tree, white flower tea; oil tea belongs to the tea family (Theaceae), an evergreen small tree. It is named for its seeds, which can be pressed for oil (tea oil) for food. Tea oil is clear in color and fragrant in taste, rich in nutrients and resistant to storage; it is a high-quality edible oil; it can also be used as lubricating oil and antirust oil in industry. Tea seed cake is both a pesticide and a fertilizer, and can improve farmland water storage capacity and control rice pests. The fruit peel is the raw material for extracting tannin extract.
How to cultivate oil tea for high yield?
1. Selection of afforestation site
In low mountain and hilly plain areas below 500 m altitude, choose acidic soil with sufficient sunlight, a slope below 25°, deep and fertile soil layers, and good drainage for planting oil tea.
2. Land preparation
(1) Land preparation methods
① Contour strip preparation: Open horizontal strips along the contour around the mountain according to row spacing, with the outer side high and the inner side low, strip width 2 m, and dig planting holes at fixed points on the strips according to plant and row spacing; hole specifications: length 50 cm × width 50 cm × depth 40 cm.
② Hole preparation: Dig holes at fixed points along the contour around the mountain according to plant and row spacing; hole length 50 cm × depth 40 cm.
(2) Density: Generally 107-167 plants per mu is required, that is, plant and row spacing of 2.3 × 2.7 m (7 × 8 chi) or 2 × 2 m (6 × 6 chi).
(3) Applying base fertilizer: After digging the holes, appropriately apply garbage compost, rice straw, Dicranopteris fern, and farmyard manure. Add 0.5 jin of lime, 0.5-1 jin of compound fertilizer, or 0.5-1 jin of phosphate fertilizer, 0.3 jin of potassium fertilizer, and 0.3 jin of nitrogen fertilizer to each hole, then backfill with topsoil, and fill the holes into a steamed bun shape for use during afforestation.
3. Afforestation
(1) Seedling selection: Generally, excellent clonal grafted seedlings are used. Seedling quality requirements are: robust growth and no pests or diseases. Two-year-old seedlings should be more than 30 cm tall with a ground diameter of more than 0.3 cm; one-year-old seedlings should be more than 15 cm tall with a ground diameter of more than 0.15 cm.
(2) Afforestation season: Early February to early March, when the soil is moist, is suitable.
(3) Afforestation method: Plant seedlings for afforestation, one plant per hole. Plant the seedling upright, spread the root system, firm the soil by pressing, and after planting cover with a layer of loose soil. The planting depth should preferably be 1-3 cm higher than the seedling root collar.
4. Tending and management
(1) Tending
After afforestation, in the first year, to protect the root system and ensure the survival rate, no tending may be done. Starting from the second year, tend 1-2 times each year, the first time in May-June and the second time in August-September, mainly for loosening soil, weeding, earthing up, and expanding holes. For plantations established by hole preparation, strips can gradually be formed through tending; the strips should be high on the outside and low on the inside, with a bamboo-node ditch opened at certain intervals. In areas with severe soil erosion, fish-scale pits can also be built.
(2) Replanting and pruning
When missing plants or diseased plants are found, replant with strong seedlings of the same age and strengthen management so that replanted seedlings and woodland seedlings grow in a balanced way.
For shaping and pruning, shaping should be the main focus, with light pruning to control excessive vegetative growth. The trunk should preferably be controlled at 0.6-0.5 m to promote the growth of main and lateral branches and form a low natural round-headed and open-center canopy.
(3) Intercropping and fertilization
During the young plantation period, use the gaps between trees to plant green manure, medicinal herbs, oil crops, and other crops, replacing tending with intertillage and fertilization, effectively controlling the growth of weeds and shrubs and improving the soil's water storage and fertilizer retention capacity.
Combine intertillage with fertilizing the young plantation, increasing organic matter, and improving the soil. Fertilization should be based mainly on organic fertilizer, combining quick-acting fertilizer with slow-acting fertilizer and organic fertilizer with inorganic fertilizer. In winter, apply 10-20 kg of farmyard manure per plant. Before the spring shoots sprout, apply additional compound fertilizer; the ratio of nitrogen, phosphorus, and potassium in the compound fertilizer is preferably 2:1:1.
(4) Pest and disease control
The main disease to control in oil tea is anthracnose. Control methods: First, combine with silvicultural measures to eliminate the source of the disease. Second, during the peak incidence period from July to September, spray 3-4 times with 1% Bordeaux mixture plus 2% tea seed cake water, or continuously spray 4-5 times with 800-fold Tuzet wettable powder solution or 500-fold 50% carbendazim solution.
The main insects to control in oil tea are scale insects, tea leaf-roller moths, and tea seed weevils. Adult tea leaf-roller moths can be trapped and killed with lights, or 500-fold 90% trichlorfon solution can be injected into branches and trunks to kill larvae. For tea seed weevils, manual catching and killing can be used, or spraying with 1000-fold 90% trichlorfon. For scale insects, spray with 1000-fold 40% omethoate solution in March-April.