Methods for Establishing High-Yield Eucommia Plantations in Mountainous Areas

Eucommia (Eucommia ulmoides) is a precious Chinese medicinal herb with the effects of tonifying the liver and kidneys, strengthening bones and muscles, benefiting the waist and knees, and relieving aching pain. It can also treat itching and dampness in the genital area and residual dribbling of urine, and has a certain therapeutic effect on hypertension. Every part of the eucommia tree is valuable. The bark is a precious medicinal material and a commonly used traditional Chinese medicine for tonifying the liver and kidneys, strengthening bones and muscles, benefiting the waist and knees, and lowering blood pressure, and it also has the effect of calming the fetus and preventing miscarriage. The bark, leaves, and fruits of eucommia are all rich in eucommia gum, which has high insulating properties, adhesion, wear resistance, and strong resistance to acids and bases, making it an important insulating raw material for manufacturing various submarine cables. Eucommia wood is tough and fine-textured with a white color, making it a good material for furniture, ships, and railway sleepers. Eucommia is easy to cultivate and has high economic benefits. It is a medicinal plant suitable for development in mountainous areas and is also a good project for the current adjustment of agricultural planting structure.

I. Seedling Cultivation

1. Selection of Nursery Site

Choose land with loose soil, moisture and fertility, and good drainage.

2. Land Preparation and Bed Making

Before raising seedlings, deep-plow and finely till the nursery land, remove weeds, and apply sufficient base fertilizer, applying 200 kg of cake fertilizer per mu. At the same time, apply 15 kg of slaked lime per mu to disinfect the soil and kill underground pests. Then make the soil fine and form seedling beds 1 m wide.

3. Seed Treatment

Collect seeds from vigorous mother trees that are fast-growing, have smooth bark, high yield, thick effective bark layer, good quality, good dryness resistance, and strong resistance, and are over 20 years old. Thirty days before sowing, soak the seeds in cold water for 10 hours; those that sink to the bottom are first-grade seeds; continue soaking to 24 hours, and those that begin to sink are medium-grade seeds; the rest that float on the water surface or are suspended in the water are low-grade seeds. Filter out the floating seeds, take out the sunken seeds, and mix them with sand at a ratio of 1:3, spread them on a cool and ventilated ground for germination treatment. After 30 days of storage, the seed kernels fully swell and begin to sprout, with young buds slightly showing white tips; then sieve out the sand grains and sow them in the nursery land.

4. Sowing Technique

Generally sow in mid-February to mid-March when the average daily temperature is stable above 10°C. Use the drill sowing method, with row spacing of 20-30 cm, sowing about 10 kg per mu. Sowing depth is 5 cm, covering with 2 cm of soil. After covering with soil, cover the seedling bed with plastic film or rice straw (or wheat straw) to prevent soil moisture evaporation and rain erosion.

II. Orchard Establishment

1. Selection of Plantation Site

Choose deep, fertile soil rich in organic matter, with loam or sandy loam texture, and avoid clayey soil as much as possible. Soil pH should preferably be 6.5-7.5. In hilly areas, the soil layer thickness should not be less than 40 cm. In mountainous areas, choose the middle and lower parts of hillsides, with a slope not greater than 25°.

2. Fine Land Preparation

For establishing high-yield eucommia plantations in mountainous areas, the land preparation method of digging planting pits within terraces should be advocated, as this can both conserve soil and water and locally dig large holes to meet the needs of plant root growth. The specific land preparation method is to first build reverse-slope terraces with a width of 2-3 m on the hillside (the terrace slope direction is opposite to the hillside slope direction), and the terrace length depends on the specific terrain and topography. After the terraces are built, determine planting points within the terraces along the terrace centerline direction at a plant spacing of 3 m, and dig planting pits centered on the planting points. The size of the planting pits should be 80 cm in length, width, and depth. When building reverse-slope terraces, keep the topsoil and mature soil within the terraces, and use the subsoil for the ridge. The outer edge of the terraces should be built firmly to prevent collapse.

3. Applying Sufficient Base Fertilizer

On the basis of fine land preparation, sufficient base fertilizer should be applied at one time. Each planting pit should be applied with 15 kg of farmyard manure, and when conditions permit, 3 kg of various cake fertilizers (crushed soybean cake, rapeseed cake, or cottonseed cake) can be added. Applying base fertilizer can not only increase nutrients and promote seedling growth, but also loosen the soil, improve soil structure, and enhance the soil's ability to retain water.

III. Planting

1. Planting Density

The density directly affects the quality of the subsequent population structure of the high-yield plantation and the level of production. Too low a density will waste land, while too high a density will cause intense competition among individual trees for light, water, and nutrients, increasing ineffective consumption, affecting tree growth, and making the height-to-diameter ratio too large, which is not only inconvenient for bark harvesting operations but also affects bark quality. Excessive density makes the forest dark and humid, leading to the occurrence of various diseases.

Bark-harvesting high-yield eucommia plantations are managed as arboriculture, and the management density directly depends on the crown diameter of eucommia under that site condition. Adult eucommia trees under medium site conditions generally have a crown diameter of about 4 m, so the plant spacing of high-yield plantation trees should be about 4 m, and the row spacing should be slightly larger, which can be 4.5 m. At a plant and row spacing of 4×4.5 m, 540-600 trees can be planted per hectare. The determination of density should also consider the quality of the site conditions where the high-yield plantation is located. If the site conditions are good, trees grow fast, canopy closes early, and crown width is large, the density should be smaller, which can be 4.5×5 m; if the site conditions are poor, trees grow slowly, canopy closes late, and crown width is small, the density can be increased, and the plant and row spacing can be reduced to 3.5×4.0 m. If single-row planting is carried out in mountainous terraces, because the site conditions are poor, the plant spacing should be reduced to 3 m. Before the high-yield plantation trees close canopy, honeysuckle or other low-stalk Chinese medicinal herbs or low-stalk crops can be intercropped under the trees; however, it should be noted that intercrops must be planted more than 1 m away from the seedlings or young trees.

2. Planting Season

Eucommia is planted in late autumn or spring, and the planting time should be early rather than late, making sure to complete planting before bud break or before leaf fall.

3. Dipping Roots in Phosphate Fertilizer Mud

Put 4 kg of superphosphate, 2 g of ABT rooting powder, and 30 kg of loess into 100 k****, and stir repeatedly to make phosphate fertilizer mud. Dipping the seedling roots in phosphate fertilizer mud before planting can promote the sprouting of new roots, help the root system quickly adhere to the soil, restore the function of absorbing water and nutrients, and improve the drought resistance of seedlings after planting.

4. Planting

First, evenly mix organic fertilizer with the excavated topsoil. One person places the seedling in the center of the pit, holds it upright by hand, so that the root collar is roughly level with the ground, and spreads the root system in the pit without tangling. Another person backfills the soil from the pit edge into the pit. When the soil is backfilled to 2/3, the sapling can be gently lifted by hand to avoid root tangling. Then firm the filled soil in the pit with the foot, water thoroughly in the pit to settle the roots, and after the water has completely seeped down, completely backfill the remaining soil into the pit and firm it again with the foot. For autumn planting, soil should also be mounded high around the seedlings to prevent freeze damage.

5. Stumping After Planting

Stumping is a very effective measure to promote height growth and upright growth of eucommia seedlings. After stumping, many sprouts often emerge below the cut. When the sprouts grow to 10-15 cm, promptly select and retain 1 sprout that grows vigorously and is suitably positioned (with no adjacent connected sprouts around it), and remove all the other sprouts. Thereafter, remove sprouts once every 10 days, taking care not to damage the retained main stem.