When is the most suitable time to apply topdressing to greenhouse beans
Greenhouse bean cultivation 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 beans in greenhouses. When it comes to fertilizing in greenhouse cultivation, although fertilizer is also 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. So when topdressing, pay attention to the timing and fertilize reasonably.
1. Fertilization time
Do not fertilize on sunny days in the greenhouse; fertilize on cloudy days, and you can also fertilize on rainy days, as not much water enters the greenhouse, which just dissolves the fertilizer without burning the roots. After one fertilization, the interval can be longer; do not fertilize just because there are yellow leaves, regardless of the time interval, as it may be caused by other reasons. For seedling-stage greenhouse seedling tray raising or direct seedling raising, once the seedlings grow to 4 cm you can apply dilute fertilizer water; apply base fertilizer to the planting soil; during the growth period you can topdress once; after pod formation, fertilize in batches.
2. Fertilization method
During seedling raising, after the seedlings emerge, once the seedlings are 4 cm tall you can apply dilute fertilizer water, and you can spray a liquid made by diluting farmyard manure soak water with water onto the soil surface. You can spray it several times. For planting base fertilizer, one greenhouse is generally given about 100 jin to 150 jin of farmyard manure. Then apply 20 jin of calcium superphosphate and 30 jin of compound fertilizer. Turn it directly into the soil and mix it with the earth. For topdressing before pod formation, topdress once with compound fertilizer, about 20 jin, to promote plant growth. After pod formation, since pods form in batches, you need to topdress multiple times, in small amounts each time, about 10 jin per application.
3. Fertilizer requirement characteristics
Beans need a lot of phosphorus and potassium during growth, especially when they begin to form pods; phosphorus fertilizer is easily fixed and hard 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 form. It may also need to be applied multiple times to ensure smooth pod formation.
4. Precautions
Because greenhouse fertilization is limited, substances that have not been fully absorbed and utilized tend to accumulate in the soil; with no rainwater to wash them away and relatively little watering in the greenhouse, harmful substances 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 to continuously dissolve it and prevent accumulation. Water droplets inside the greenhouse must all be wiped off and must not be allowed to fall back into the soil.
For greenhouse bean cultivation, fertilization should be done at the appropriate time, with the appropriate amount, and according to the fertilizer requirement characteristics of beans. When fertilizing, pay attention to the problem of fertilizer burn.