What Fertilizer to Apply to Bitter Melon (the "Natural Insulin") at Each Growth Stage and the Dosage per Mu
Bitter melon is a vegetable cultivated 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 cultivated 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?
I. Base fertilizer for bitter melon
Bitter melon is not strict about soil conditions, but it likes fertilizer and water and should not be grown in continuous cropping. It is best to choose a clay loam that has not grown cucurbit crops for 3 consecutive years, has deep soil layers, high organic matter content, and good fertilizer and water retention. Before planting, apply sufficient base fertilizer: 4000-5000 kg of fully decomposed organic fertilizer and 20-30 kg of three-element compound fertilizer per mu. After spreading the fertilizer, plow once. 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.
II. Topdressing for bitter melon
Bitter melon has many female flowers, can bloom and bear fruit continuously, is picked successively, and has a long harvest period. Therefore, bitter melon has a long growth period and consumes a large amount of fertilizer and water over its lifetime. In addition to applying sufficient base fertilizer, during the middle and late fruiting stages, great attention must be paid to timely topdressing and irrigation. Generally, after entering the melon harvest period, water once every 7-10 days, and apply chemical fertilizer with water every other time clear water is applied. The topdressing amount is 10-15 kg of urea per mu, or 10-15 kg of three-element compound fertilizer can be applied. During the full fruiting stage, apply phosphorus fertilizer 2-3 times, with 10-15 kg of superphosphate each time. 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 set, small melons, low yield, strong bitterness, and deteriorated quality.
Topdressing for bitter melon should adopt a concentrated fertilization method, such as digging ring-shaped trenches, which can greatly improve fertilizer utilization.
Specific method: dig a ring-shaped trench 20 cm inside the bitter melon plant, or dig a 0.5 m long strip trench 20 cm inside the bitter melon plant, then apply the topdressing fertilizer into the trench, cover the trench with soil, and water. It should be noted that after each topdressing of bitter melon, water must be applied promptly so that the plant can absorb nutrients well.
III. 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 by flushing it with water. This is very convenient and can evenly apply fertilizer into the soil, but 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, fertilizer utilization will be very low and waste will be serious. Therefore, a concentrated fertilization method should be used, which is both beneficial for crop absorption and can improve fertilizer utilization.
2. One-sided and heavy application of nitrogen fertilizer: although bitter melon is a crop that requires more nitrogen fertilizer, excessive nitrogen fertilizer application not only easily causes excessive vegetative growth of bitter melon plants, affecting yield and quality, but also reduces the stress resistance of bitter melon, aggravates the occurrence of bitter melon diseases, and at the same time easily produces deformed melons.