The main methods of using boron fertilizer are as follows:
1. Dip the roots. Use 0.05 to 0.15 kg of borax per mu, dissolve it in a small amount of water (hot water at 40°C), then add fine soil and water to make a paste, and dip the roots when transplanting rapeseed or other crop plants.
2. Make base fertilizer. Use 0.5-1 kg of borax per mu, mix it with fine dry soil, phosphate fertilizer or nitrogen fertilizer, and apply it when cotton or other crops are planted or transplanted. Once applied, the fertilizer effect can last for 2 to 3 years, and the yield is generally increased by more than 10% in the current season. Boron mud is often used as a base fertilizer, and the price is low. The dosage is about 15 kg per mu. It can be mixed with organic fertilizer and applied. For citrus, apple and other fruit trees, use 1.5 to 2 kilograms of boron mud per plant. When making a base fertilizer, it must be applied evenly to avoid local boron concentration that may cause crop poisoning. Boron mud has alkaline reaction and contains 30-40% of magnesium (MgO), which is suitable for southern soil.
3. Seed soaking. Soak corn and sorghum seeds with a concentration of 0.02-0.05% borax or boric acid solution for 4 to 5 hours, and wheat seeds for 3 hours, remove and dry (do not explode in the sun) before sowing. Bean crops and crops grown on saline-alkali soil are not suitable for soaking seeds.
4. Seed dressing. Use 0.2 to 0.5 grams of borax or boric acid for every 0.5 kg of seeds. When the seeds are mixed, the solution should be completely absorbed, and the seeds should be sown after drying in the shade.
5. Foliar spraying. Use 0.05-0.1 kg of borax or 0.05-0.07 kg of boric acid per acre, add 50 kg of water after dissolving the water (with a spraying concentration of 0.1-0.2%), and apply foliar spraying after 4 pm on a sunny day. The dosage of the solution depends on the size of the seedlings, the seedlings are mostly sprayed, and the seedlings are sprayed less frequently.
Boron fertilizer directly affects the development of crop reproductive organs and should be applied as soon as possible. Boron has poor ability to function in plants, so it should be sprayed many times. For example: 2 to 3 days before the cutting of rapeseed, 100 grams of borax per acre of seedbed is mixed with 50 kilograms of aqueous solution for spraying, which can increase the survival rate. Spray 2 to 3 times from bolting to the first flowering stage. The cotton should be sprayed at the bud stage, and it is better to spray it for 2 to 3 times every half month. It is better to spray fruit trees in the young fruit stage and blooming stage. It can also be sprayed with Bordeaux mixture and 0.5% urea to form a mixed solution, and 0.2-0.3% borax or boric acid solution can be used.
Points to note when using boron fertilizer:
When preparing the borax or boric acid aqueous solution, stir it. After the borax or boric acid is completely dissolved, pour it into the sprayer. Do not put borax or boric acid directly into the sprayer, so as not to affect the effect.
The concentration difference between crops' lack, proper amount and excess of boron is small. Special attention should be paid to the amount of boron fertilizer and application techniques, especially on sandy soil, because sandy soil has poor buffering properties. In production, the soaked seeds cannot emerge because of the high concentration of boron fertilizer; the soil is originally high in content and after the application of boron fertilizer, cases of poisoning are often seen, and we should pay attention to it. According to reports, some factories did not pay attention to the treatment of boron mud waste residue or boron-containing wastewater, and random discharge caused the water-soluble boron in soil and groundwater to exceed a certain limit, and crops would be poisoned to reduce production, and sometimes no pellets were harvested. People and livestock drink boron-containing well water that exceeds the standard will cause "boron enteritis".
Crops with boron poisoning are also sensitive to flower organs, with symptoms such as incomplete pollination, baldness, increased stubborn grains, and deformities of fruits and vegetables. The edges of corn leaves and melon leaves in the middle of growth form a closed yellow border with very clear boundaries, which is a special symptom of boron poisoning. Generally speaking, vegetable crops suffer more damage than cereal crops, especially cucumbers. Using cucumber as an indicator crop for boron damage (golden closed borders appear on the edges of the leaves), more accurate information can be obtained.