First, the management of soil, fertilizer and water.
1 Soil management Walnuts have deep roots and like breathable soil. Autumn can be combined with autumn fertilization for garden cleaning and deep ploughing. After harvesting the fruits in autumn, before defoliation, clear the sundries in the orchard and dig the soil deeply, with a depth of 25-40 cm. The high temperature at this stage coincides with the second growth peak of the root system. Damaged roots are easy to heal and grow new roots, and soil nutrients are transformed quickly, which is beneficial to the accumulation of nutrients in trees.
2 fertilization
(1) stage: generally, it is carried out in central and southern Hebei from early September to late June after walnut harvesting. The early growth of walnut fruit consumes a lot of nutrients, which reduces the ability of the tree to resist the invasion of pathogens. This season, the soil moisture is suitable, the root system of the tree is at the peak of its growth activity in autumn, and the short-branch flower buds that have differentiated into annual fruits also need sufficient nutrition to ensure the growth of the tree and the fruits of the next year. In order to ensure the growth of trees and the results of next year, it is necessary to supplement fertilizers in time and supply sufficient nutrients.
(2) Fertilizer selection: Walnut trees like fertilizer. In autumn, organic fertilizers and biological fertilizers suitable for the growth of walnut trees can be selected as the main fertilizers to improve the soil, prevent hardening and promote ventilation, and at the same time, moderate amounts of medium and trace element fertilizers such as nitrogen, phosphorus and potassium can be added.
(3) Fertilization amount: 30 kg of high-quality organic fertilizer, 0.3 kg of second-generation prebiotic bacterial fertilizer, 2 kg of nitrogen, phosphorus and potassium macroelement fertilizer and 200 g/mu of ciba boron and zinc microelement fertilizer are applied to each first-bearing tree; At the full fruit stage, 50 kg of high-quality organic fertilizer, 0.5 kg of second-generation prebiotic biological bacterial fertilizer, 4 kg of nitrogen, phosphorus and potassium macro-element fertilizer and 300 g/mu of ciba boron and zinc micro-fertilizer were applied to each plant.
(4) Fertilization method: combined with deep ploughing and disc expansion. 2-4-year-old early-bearing trees can be turned into the soil with a depth of about 20 cm after spreading fertilizer under the crown. Trees over 5 years old can be fertilized with furrow, with a width of 50cm and a depth of 40cm. After the fertilizer and soil are mixed evenly, the furrow can be filled back into the furrow, or the furrow can be turned over every other year after spreading, so as to make up for the shortcoming of high fertilization concentration in the furrow. Ciba boron-zinc fertilizer should be mixed with fine soil or fine sand evenly before application because of its small dosage.
3. Water: After deep ploughing or furrowing and fertilizing, it should be watered in time and fully, and it can be watered again before the soil freezes in dry years.
The above management methods not only provide the nutrients needed by walnuts, but also help to form flower buds and accumulate nutrients, and play a role in pruning the roots.
Second, shaping and pruning
1 pruning time
Pruning walnut trees during dormancy is easy to bleed, weaken the tree vigor and even cause local branches to die. The most suitable pruning period is before defoliation in autumn or after germination in spring. Pruning is best between "autumnal equinox" and "cold dew" in autumn, which is beneficial to the early healing of wounds in that year. If the pruning workload is heavy, it can also be pruned from 30 days after defoliation to 25 days before germination in winter to reduce the adverse effects of bleeding on trees.
Walnut trees are suitable for tree shapes.
At present, high-quality early-fruiting thin-skinned walnuts mainly adopt three tree shapes: small crown sparse layer shape, happy shape and spindle shape. For varieties with good fertilizer and water conditions, thick soil layer or strong growth potential, the planting density is small, and the small crown sparse layer shape or spindle shape can be used, otherwise the heart shape or improved heart shape can be used.
3 pruning method
(1) Key points of pruning young trees Walnut trees are rich in nutrients at the young tree stage, the branches grow rapidly, and the crown expands year by year. At this time, attention should be paid to cultivating the trunk, retaining the main branches and auxiliary branches, pruning crowded branches, clustered branches and weak branches in time, and leaving more fruiting branches on the crown. Pruning is best combined with pruning, and pruning of dense trees is supplemented by pruning. It not only ensures the uniform distribution and symmetrical growth of the main branches, but also makes the crown level clear, transparent and unbiased, ensures the balanced development of the tree potential, and gradually cultivates a plump tree with large fruit yield.