Fertilizer requirements of mulberry trees in China and high-yield fertilization techniques and timing: The mulberry tree is a perennial deciduous woody plant. Its leaves are harvested multiple times each year for silkworm rearing, removing large amounts of nutrients from the soil. Therefore, mulberry trees have relatively high nutrient needs. Producing 100 kg of fresh mulberry leaves requires approximately 1.5-2 kg of nitrogen, 0.8-1.2 kg of phosphorus, and 1.0-1.6 kg of potassium. Among these, nitrogen and potassium are needed in the greatest amounts. Nutrient uptake by mulberry trees varies across different periods. In spring, as mulberry trees sprout branches and leaves, before the fifth leaf unfolds, the nutrients required mainly come from reserves stored within the tree. After the sixth and seventh leaves unfold, branches and leaves grow rapidly, and nutrient uptake accelerates. By the spring silkworm season (May in areas south of the Yangtze River), mulberry tree growth enters the peak period, and nutrient uptake reaches its first peak. After summer pruning, root nutrient uptake stops. As new sprouts emerge, mulberry branches and leaves grow rapidly again, gradually entering the second vigorous growth period (June, July, and August in areas south of the Yangtze River), with nutrient uptake correspondingly reaching a second peak. Entering autumn and winter, mulberry tree growth slows, nutrient uptake decreases, until dormancy.
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<p style="text-indent:2em;">Mulberry fertilization should determine the amount and timing of application based on nutrient requirements. At an annual fresh leaf yield of 2 tonnes per 667 sq m, it is necessary to apply 30-35 kg of nitrogen, 12-14 kg of phosphorus, and 15-17 kg of potassium, with a nitrogen-phosphorus-potassium ratio of 10:4:5 (if producing silkworm eggs, the nitrogen-phosphorus-potassium ratio is 5:3:4).</p>
<p style="text-indent:2em;">Mulberry fertilization is divided into spring fertilizer, summer fertilizer, autumn fertilizer, and winter fertilizer. The type and amount of fertilizer should be determined according to seasonal changes, the growth patterns of mulberry trees, and their fertilizer needs.</p>
<p style="text-indent:2em;">1. Spring fertilizer: When mulberry trees sprout in spring, they consume nutrients stored within the tree. According to research, spring fertilizer is only absorbed and utilized by mulberry trees when approximately the fifth spring leaf has unfolded. Spring fertilizer is generally nitrogen-based, such as urea, at 15-20 kg per mu. To reduce fertilizer loss, it should be applied in two split applications, in mid-March and early April respectively.</p>
<p style="text-indent:2em;">2. Summer fertilizer: Entering June and July, with high temperatures and ample rainfall, this is the period of most vigorous mulberry growth and the greatest nutrient demand. If fertilizer is applied promptly to supply sufficient nutrients, mulberry branches and leaves grow vigorously, branches are long, and summer and autumn leaf yields are high. To improve fertilizer efficiency, two split applications are recommended. The first should be applied as early as possible after the spring silkworm rearing ends, at 20 kg of urea per mu (late May); the second in early to mid-July, at 15 kg of urea per mu, combined with 20 kg of phosphate fertilizer and 5-10 kg of potassium fertilizer. Apply in furrows or broadcast with weeding, and mix the fertilizer into the soil.</p>
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<p style="text-indent:2em;">3. Autumn fertilizer: Generally applied in mid to late August, at 15 kg of urea per mu. Autumn fertilizer can sustain the continued growth of mulberry branches and leaves, delay the hardening of autumn leaves, and improve autumn leaf quality. It can also increase the stored nutrients in mulberry trees, enhancing cold resistance and the sprouting rate the following spring, and also helps increase spring leaf yields. However, autumn fertilizer should not be applied too late or in excessive amounts, at the latest before the end of August, and should be appropriately combined with phosphorus and potassium fertilizers.</p>
<p style="text-indent:2em;">4. Winter fertilizer: Fertilizer applied after mulberry leaves fall is called winter fertilizer. Unlike spring, summer, and autumn fertilizers, winter fertilizer has no direct effect on leaf yield. Its main purpose is to improve soil aggregate structure and increase soil fertility. Winter fertilizer generally uses organic materials such as compost, garbage, and rice straw, which decompose through the action of soil microorganisms, releasing nitrogen, phosphorus, and potassium as well as other inorganic nutrients for mulberry trees to absorb and utilize. Its fertilizer effect is slow but lasting, with comprehensive nutrients.</p>
Fertilizer Requirements of Mulberry Trees in China and High-Yield Fertilization Techniques and Timing: The mulberry tree is a perennial deciduous woody plant. Its leaves are harvested multiple times each year for silkworm rearing, removing large amounts of nutrients from the soil. Therefore, the mulberry tree has relatively high nutrient needs: producing every 100 kg of fresh mulberry leaves requires approximately 1.5-2 kg of nitrogen, 0.8-1.2 kg of phosphorus, and 1.0-1.6 kg of potassium. Among these, nitrogen and potassium are needed in the greatest amounts. Nutrient uptake by mulberry trees varies at different stages. In spring, as the tree sprouts branches and leaves, before the fifth leaf unfolds, the nutrients required come mainly from reserves stored within the tree. After the sixth and seventh leaves unfold, branches and leaves grow rapidly, and nutrient uptake accelerates. By the spring silkworm rearing period (May in areas south of the Yangtze River), mulberry growth enters its vigorous phase, and nutrient uptake reaches its first peak. After summer pruning, root nutrient uptake stops. As the tree re-sprouts, branches and leaves grow rapidly, gradually entering the second vigorous growth period (June, July, and August in areas south of the Yangtze River), and nutrient uptake reaches a corresponding second peak. Entering autumn and winter, mulberry growth slows, nutrient uptake decreases, until dormancy.
Mulberry fertilization should be based on fertilizer requirements to determine application rates and timing. Based on an annual production of 2 tons of fresh leaves per 667 sq m, 30-35 kg of nitrogen, 12-14 kg of phosphorus, and 15-17 kg of potassium are required, with a nitrogen-phosphorus-potassium ratio of 10:4:5 (if producing silkworm eggs, the nitrogen-phosphorus-potassium ratio is 5:3:4).
Mulberry fertilization is divided into spring fertilizer, summer fertilizer, autumn fertilizer, and winter fertilizer. The type and amount of fertilizer should be determined according to seasonal changes, the growth patterns of the mulberry tree, and its fertilizer needs.
1. Spring fertilizer: When mulberry trees sprout in spring, they consume nutrients stored within the tree. According to research, spring fertilizer is only absorbed and utilized by the mulberry tree when approximately the fifth spring leaf has unfolded. Spring fertilizer is generally nitrogen-based, such as urea, at 15-20 kg per mu. To reduce fertilizer loss, it should be applied in two split applications, in mid-March and early April respectively.
2. Summer fertilizer: Entering June and July, with high temperatures and ample rainfall, this is the period of most vigorous mulberry growth and the greatest nutrient demand. If fertilizer is applied in time to supply sufficient nutrients, mulberry branches and leaves grow vigorously, branches are long, and summer and autumn leaf yields are high. To improve fertilizer efficiency, two split applications are recommended. The first should be applied as early as possible after the spring silkworm rearing ends, at 20 kg of urea per mu (late May); the second in early to mid-July, at 15 kg of urea per mu, combined with 20 kg of phosphorus fertilizer and 5-10 kg of potassium fertilizer, applied in furrows or broadcast with weeding, ensuring the fertilizer is mixed into the soil.
3. Autumn fertilizer: Generally applied in mid-to-late August, at 15 kg of urea per mu. Autumn fertilizer allows mulberry branches and leaves to continue growing, delays the hardening of autumn leaves, and improves autumn leaf quality; it also increases stored nutrients in the mulberry tree, enhancing cold resistance and the germination rate the following spring, and also helps increase spring leaf yields. However, autumn fertilizer should not be applied too late or in excessive amounts, at the latest before the end of August, and should be appropriately combined with phosphorus and potassium fertilizers.
4. Winter fertilizer: Fertilization after mulberry leaves fall is called winter fertilizer. Unlike spring, summer, and autumn fertilizers, winter fertilizer has no direct effect on leaf yield. Its main purpose is to improve soil aggregate structure and increase soil fertility. Winter fertilizer generally uses organic materials such as compost, garbage, and rice straw, which decompose through the action of soil microorganisms, releasing the three key elements of nitrogen, phosphorus, and potassium as well as other inorganic nutrients for mulberry uptake and utilization. Its fertilizer effect is slow but lasting, with comprehensive nutrients.