What fertilizer is best for bitter melon, the "natural insulin"? How should it be fertilized at each growth stage? How much fertilizer is needed per mu?
Bitter melon is a vegetable grown in both northern and southern regions of China, and it is deeply loved by people for its effects of clearing heat and detoxifying, lowering blood sugar, and beautifying the skin. It is currently grown in many regions, but to grow bitter melon well, management work must be done properly. So what fertilizer is best for bitter melon? How should it be fertilized at each growth stage? How much fertilizer is needed per mu?
1. Base fertilizer for bitter melon
Bitter melon is not strict about soil conditions, but it likes fertilizer and water and is intolerant of continuous cropping. It is best to choose a clay loam with deep soil layers, high organic matter content, and good fertilizer and water retention where cucurbit crops have not been grown for 3 consecutive years. Before planting, apply sufficient base fertilizer, with 4000-5000 kg of fully decomposed organic fertilizer and 20-30 kg of three-element compound fertilizer per mu. After spreading the fertilizer, carry out one plowing. For open-field cultivation, generally make flat beds or raised beds 150 cm wide; in greenhouses, planting can be appropriately sparser, and large and small ridges of 60 cm and 80 cm or raised beds 150 cm wide can be made.
2. Topdressing for bitter melon
Bitter melon has many female flowers and can bloom and bear fruit continuously, with successive picking and a long harvest period. Therefore, bitter melon has a long growth period and consumes a large amount of fertilizer and water over its life. In addition to applying sufficient base fertilizer, during the middle and late fruiting stages, great importance should be attached to timely topdressing and irrigation. Generally, after entering the melon harvest period, water can be applied once every 7-10 days, and every other time chemical fertilizer can be applied with the irrigation water, with a topdressing rate of 10-15 kg urea per mu, or 10-15 kg of three-element compound fertilizer. During the full fruiting stage, apply phosphate fertilizer 2-3 times, each time with 10-15 kg calcium superphosphate. In the late fruiting stage, attention should be paid to strengthening the supply of fertilizer and water; otherwise, fertilizer deficiency and premature aging are likely to occur, with thin and weak plant growth, yellow-green leaf color, thin and weak side branches, fewer melons, small melons, low yield, strong bitterness, and deteriorated quality.
Topdressing for bitter melon should adopt a concentrated fertilization method, such as digging ring-shaped furrows for application, which can greatly improve the fertilizer utilization rate.
Specific method: dig a ring-shaped furrow 20 cm inside the bitter melon plant, or dig a strip-shaped furrow 0.5 m long 20 cm inside the bitter melon plant, then apply the topdressing fertilizer into the furrow, cover the furrow with soil, and water. It should be noted that after each topdressing of bitter melon, water must be applied promptly, as only then will the plant's nutrient absorption be better.
3. Incorrect fertilization methods for bitter melon
1. Flushing fertilizer with large amounts of water: The topdressing method commonly used by netizens growing bitter melon is applying fertilizer with irrigation water. This is very convenient and can evenly apply fertilizer into the soil. However, this method of topdressing bitter melon is not advisable. The reason is that bitter melon is planted at a relatively low number of plants per mu, only 200-300 plants per mu. If topdressing is done by flushing with water, the fertilizer utilization rate will be very low, causing serious waste. Therefore, a concentrated fertilization method should be adopted, which is not only good for crop absorption but can also improve the fertilizer utilization rate.
2. Partial and heavy application of nitrogen fertilizer: Although bitter melon is a crop that requires a relatively large amount of nitrogen fertilizer, excessive nitrogen fertilizer application not only easily leads to excessive vegetative growth of bitter melon plants, affecting yield and quality, but also reduces the stress resistance of bitter melon and aggravates the occurrence of bitter melon diseases. At the same time, it also easily produces deformed melons.