Pruning and Fertilizer Management of Hong Ling Walnut Trees
Liang Hongjun, Jia Zhihua
Hebei Green Ridge Fruit Industry Co., Ltd. 054300
In recent years, dried fruits have become increasingly popular among consumers worldwide. Among the four major dried fruits, walnuts rank first due to their rich nutritional value and unique flavor, making them a favorite for people all over the globe. With the growing demand, walnut production has gradually shifted toward large-scale and standardized management practices. Over the past seven years since the company was established, we have accumulated practical experience in walnut cultivation and developed effective pruning techniques along with corresponding fertilizer and water management strategies. After three years of experimental observation, we found that this method is simple, efficient, and significantly improves fruit yield and quality compared to conventional methods. It not only increases the fruiting rate but also ensures stable and high yields. Traditional walnut pruning methods mainly include thinning, long-distance cutting, and short-cutting. These techniques have played an important role in boosting walnut production and increasing income. However, due to the inherent characteristic of "injurious flow" in walnut trees, excessive pruning can lead to significant nutrient loss. In summer, when growth is vigorous, canopy closure often occurs, resulting in poor air circulation and light penetration, which negatively affects fruit development. This may require multiple prunings, increasing the number of wounds and, to some extent, hindering tree growth. By using long branch pruning, the amount of pruning is reduced, minimizing nutrient loss and maintaining better tree health. Below are the current pruning techniques and related fertilizer and water management practices: 1. Newly Planted Walnut Trees 1) Fertilization Newly planted walnut trees have small root systems that are shallow and not drought-resistant. Therefore, it's crucial to focus on strengthening fertilizer and water management. From April to June, nitrogen fertilizer is primarily applied along with potassium fertilizer. From July to August, nitrogen is stopped, and potassium top-dressing is used instead. Urea foliar spray is also applied in July. The fertilization principle is to apply fewer amounts more frequently. Fertilization is done 3–4 times, with timing set in early April, mid-May, mid-June, and early July. In May, about 0.2kg of nitrogen fertilizer is applied, while the total for April and June is combined. In July, approximately 0.1kg of potassium fertilizer is used. Watering should be done alongside fertilization, and attention must be paid to the risk of dry hot winds in May to prevent leaf burn. At the end of August, strip-shaped base fertilizer trenches are dug along the seedling rows. The trenches are 40 cm wide, 30 cm deep, and spaced 50 cm apart. Five kilograms of chicken manure and 1.5 kg of phosphate fertilizer are applied. After fertilizing, water once and cover the soil with frozen water before it thaws. 2) Pruning After the shoots spread, all new shoots below 40 cm from the main trunk should be removed, leaving 4–5 shoots. In June, light tip pruning is performed to encourage full shoot growth. Remove dense branches, weak branches, small branches, and short branches (less than 10 cm). In winter, cut back branches longer than 30 cm to 25–30 cm to shape the tree properly. 2. One-Year-Old Trees 1) Fertilization The timing and amount of top-dressing are adjusted as follows: early April (0.5kg urea, 0.25kg potassium sulfate), mid-May (0.25kg compound fertilizer of urea and potassium sulfate), and mid-June (0.15kg potassium sulfate compound fertilizer). Base fertilizer is applied on the opposite side of last year’s fertilizer trench, moving outward as the canopy expands. The amount of fertilizer is similar to that used for newly planted trees. Watering is best done through water-saving irrigation methods such as drip or micro-tube injection. Ground watering should be increased in frequency, and each watering session should be reduced in volume, provided the tree's needs are met. Watering should always be combined with fertilization. 2) Pruning Although saplings may already be fruiting, it's best to remove the young fruits to allow the tree to concentrate its nutrients on growth and development. In summer, remove any unused branches—those that are dense, diseased, insect-infested, weak, or too short. In June, pinch back 3–4 buds to select the second branch. 3. Three-Year-Old Trees 1) Fertilization and Watering During this stage, the trees enter the early fruiting period, so the amount of fertilizer should be increased. Top-dressing includes 1.25kg of urea and 0.5kg of potassium sulfate compound fertilizer. Adjust the quantity based on the tree's age and growth condition. Apply 10kg of chicken manure and 2kg of superphosphate in the same year. 4. Trees Over Four Years For trees over four years old, the focus shifts to maintaining productivity and ensuring balanced growth. Pruning should be done carefully to avoid over-thinning, and regular monitoring of tree health is essential. Fertilization should be adjusted according to the tree's needs, with a balance between nitrogen, phosphorus, and potassium. Watering should continue to be efficient, using drip or micro-irrigation systems to conserve water and promote healthy root development. Regular inspections for pests and diseases are also recommended to maintain the overall health of the orchard.Ultrasonic Surgical System，High-Frequency Electrosurgical System
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