What fertilizer is best for wax gourd (winter melon) at each growth stage, and how much fertilizer is needed per mu

Wax gourd, also known as white gourd, earth sesame, white winter melon, etc., is a common vegetable in southern China. It is widely grown because it stores well, has low planting costs, high yields, and is rich in nutritional value. But to grow wax gourd well, besides the variety, it also has a certain relationship with light, fertilizer, and other factors. So what fertilizer is good for wax gourd? How should it be fertilized at each growth stage? How much fertilizer is needed per mu?

1. Fertilizer requirement pattern:

Wax gourd likes to grow in a warm environment, so its fertilizer needs are the same as those of other crops. Of the three key elements, nitrogen, phosphorus, and potassium, it absorbs the most potassium, followed by nitrogen, and the least phosphorus. The specific amount of fertilizer applied should be determined according to the climate, fertilizer type, soil properties, plant growth stage, and cultivation conditions.

2. Fertilization techniques:

1. Base fertilizer for wax gourd

Wax gourd has a long growth period and a high fertilizer requirement, so sufficient base fertilizer must be applied before transplanting. This is especially important in areas where there is a lot of rain during the peak growth period of wax gourd and it is inconvenient to apply fertilizer. Generally, 6000-7000 kg of decomposed organic fertilizer is applied per mu. If the soil fertility is relatively low, 50-70 kg of potassium sulfate-based three-element compound fertilizer (such as 15-15-15) can be added per mu, broadcast during land preparation, then deeply plowed 25-30 cm, harrowed fine and leveled, or applied in furrows when making beds. For transplanting wax gourd, a seedling age of 3-4 leaves is best. If the seedlings are too old, they are less likely to root and recover after transplanting; if too young, early growth after transplanting is slow. If plastic film is used after transplanting, water thoroughly under the film.

Because wax gourd needs relatively more calcium, and acidic soil in the south is prone to calcium deficiency, it is recommended that for overly acidic soil, about 50 kg of lime per mu can be mixed with organic fertilizer and applied together (the organic fertilizer must be decomposed before it can be mixed with lime).

2. Seedling fertilizer for wax gourd

During the seedling stage of wax gourd, small amounts of water and light fertilizer should be used. One week after transplanting, when the plants begin to recover, water can be applied to help them recover. If the base fertilizer is insufficient, a light topdressing can be applied after recovery. Generally, decomposed manure water at a concentration of 10%-30% is used, or urea, or high-nitrogen compound fertilizer is applied in holes. The amount should be small.

3. Vine fertilizer for wax gourd

Before wax gourd begins to vine, topdressing accounts for 30%-40% of the total topdressing. Fertilization at this stage is mainly to promote vine and leaf growth, but it should not be too concentrated or too much, otherwise the leaves will become dark green, internodes will shorten, and vine tips will turn yellow. If the base fertilizer is sufficient and the plants are growing vigorously, no fertilizer is needed; if fertility is not very sufficient, furrow application can be done when the seedlings have 5-6 leaves, applying 20 kg of potassium sulfate compound fertilizer (such as 15-15-15 sulfur-containing compound fertilizer) per mu. From the appearance of female flowers to fruit set, fertilizer and water should be appropriately controlled, especially nitrogen fertilizer, to avoid excessive vine and leaf growth that causes fruit abortion.

4. Flowering and fruiting fertilizer for wax gourd

Flowering and fruiting fertilizer accounts for 60%-70% of the total topdressing. This fertilization is very important for wax gourd growth and is generally carried out after the fruit has set, to prevent flower and fruit drop, and nitrogen, phosphorus, and potassium fertilizers should all be included. After the fruit has set firmly, fruit-promoting fertilizer should be applied in time, with about 20 kg of three-element compound fertilizer per mu. At the same time, side vines should be removed in time to promote fruit set. For small wax gourds, keep a fruit as soon as a female flower appears, leaving 2-4 per plant; for large wax gourds, it is suitable to keep fruit at the second and third female flower nodes, leaving only 1 fruit per plant.

(1) Early fruit enlargement stage

In the early stage of wax gourd fruit enlargement, spraying 0.2% phosphorus fertilizer 1-2 times can accelerate fruit enlargement. In addition, dead grass or gourd leaves should be used in time to cover the fruit (to prevent direct strong light from causing sunscald).

(2) Middle and late fruit enlargement stage

In the middle and late stages of wax gourd fruit enlargement, it is suitable to apply light fertilizer frequently, watering thoroughly each time, with topdressing about every 15 days, preferably alternating fertilizer and water. Each time, apply 10 kg of urea, 10 kg of diammonium phosphate, and 15 kg of potassium sulfate per mu, or apply about 25 kg of high-nitrogen-potassium compound fertilizer per mu. The amount and frequency of fertilization can be adjusted according to the earlier fertilization situation and the length of the harvest period. If the harvest period is long, the fertilization amount should be appropriately increased. When applying, a furrow or hole can be opened 40-50 cm from the roots and the fertilizer placed in it; chemical fertilizer can also be mixed with water into a 1.5%-2.0% liquid fertilizer and poured 40-50 cm from the roots, so as to avoid damaging the root system during fertilization. Where conditions allow, high-quality organic fertilizer can also be used for topdressing (such as 75 kg of soybean cake and 4000 kg of diluted manure water per mu).

(3) Harvest period

10-15 days before harvesting wax gourd, fertilizer and water application should be stopped to reduce the water content of the fruit and increase its storage tolerance. Harvest at the appropriate time according to the physiological maturity of the wax gourd.

5. Fertilization precautions

(1) Do not apply nitrogen fertilizer alone

Many wax gourd growers always think that the more base fertilizer, the better, and from the seedling stage they apply more nitrogen fertilizers such as ammonium sulfate, manure water, and urea, and even more during the fruiting stage. This increases costs due to excessive fertilizer application, and often causes the occurrence and development of fusarium wilt and phytophthora blight; applying too much nitrogen fertilizer in the middle and late fruiting stages often induces a large outbreak of fruit cottony rot.

(2) Fertilize according to weather conditions

Choose sunny days for fertilization. If it is rainy, try to apply three or four hours before the rain so that the soil can fully absorb the nutrients. If topdressing is done before or after heavy rain, it often aggravates the occurrence of diseases.