When is the right time to fertilize greenhouse-grown yardlong beans
Greenhouse cultivation of yardlong beans can be done in early spring or as a late-autumn delayed crop, which can reduce many pests and diseases. That is why many people choose to grow yardlong beans in greenhouses. As for fertilizing under greenhouse cultivation, although fertilizer is still applied according to the growth stage, the amount applied is much smaller, the fertilization system is different, and there is also the problem of fertilizer burn easily occurring. So when topdressing, pay attention to timing and fertilize reasonably.
1. Fertilization timing
Do not fertilize in the greenhouse on sunny days; fertilize on cloudy days, and you can also fertilize on rainy days. The amount of water entering the greenhouse is not much, just enough to dissolve the fertilizer, and it will not burn the roots. After one fertilization, the interval can be longer. Do not fertilize just because there are yellow leaves, regardless of the time interval; it may be caused by other reasons. During the seedling stage, whether raising seedlings in greenhouse seedling trays or direct sowing, once the seedlings grow to 4 cm, a light fertilizer solution can be applied; soil base fertilizer at transplanting; during the growth period, topdressing can be done once; after pod setting, fertilize in batches.
2. Fertilization methods
When raising seedlings, after emergence, once the seedlings are 4 cm tall, a light fertilizer solution can be applied; farmyard manure leachate diluted with water can be sprayed on the soil surface. It can be sprayed several times. For base fertilizer at transplanting, one greenhouse is generally given about 100 jin to 150 jin of farmyard manure. Then apply 20 jin of superphosphate and 30 jin of compound fertilizer. Turn it directly into the soil and mix it with the soil. For topdressing before pod setting, apply compound fertilizer once, about 20 jin, to promote plant growth. After pod setting, pods are set in batches, so topdressing must be done multiple times, with small amounts each time, about 10 jin per application.
3. Fertilizer requirement characteristics
During the growth of yardlong beans, a large amount of phosphorus and potassium is needed, especially when pods begin to form. Phosphorus fertilizer is easily fixed and difficult to absorb, so the earlier it is applied, the better. Some potassium fertilizer should also be applied in the early stage to grow roots and stems, but it is mainly applied in the later stage when pods are forming. It may also need to be applied multiple times to ensure smooth pod setting.
4. Precautions
Because greenhouse fertilization is limited, it easily accumulates in the soil. If there are substances that have not been fully absorbed and used, and there is no rainwater to wash them away, while greenhouse watering is relatively less, harmful substances can easily accumulate. Therefore, when fertilizing, be sure to use an appropriate amount each time and do not apply too much. Fertilization must be accompanied by drip irrigation water so that it continuously dissolves and does not accumulate. Water droplets in the greenhouse must all be wiped off and must not fall back into the soil.
For greenhouse yardlong bean cultivation, fertilization should be done at the appropriate time, with the appropriate amount, and according to the fertilizer requirement characteristics of yardlong beans. Pay attention to the problem of fertilizer burn when fertilizing.