How to save vegetables over-fertilized?

One, excess nitrogen fertilizer

1, symptoms. The leaves of fruit and vegetable vegetables are large and dark green, with long petiole and internodes. The plants are susceptible to growth, yellowing occurs between veins (the lower leaves of the tomato are easy to curl), the buds are slender (the ovary of the melons is smaller), and fruit Slow growth, easy to drop, fruit drop. Tomato is easy to get rot of the umbilical rot, celery is easy to get heart rot.

2, the reasons for the occurrence. Precocious fruits and vegetables are promoted prematurely before fruit set and the reproductive growth of plants is inhibited. Nutrient growth is too prosperous, and the leaves cover the air and light is poor, resulting in falling flowers and falling fruit. Too much nitrogen affects the plant's absorption of calcium, as well as the occurrence of tomato rot and celery heart rot.

3, control methods

(1) Cultivate strong seedlings. Control the water and fertilizer in the shed to harmonize the vegetative growth and reproductive growth of fruits and vegetables. Set the seedlings in due course before the fruiting period to prevent plant growth. The temperature in the shed is appropriately lowered, and the night temperature is maintained at 12-14°C.

(2) Balanced fertilization. According to the demand for nutrients at different stages of vegetable growth, nitrogen, phosphorus, and potassium should be balanced and nitrogen fertilizer should be avoided.

(3) Appropriate calcium supplementation. For the soil with more advanced nitrogen fertilizer or more nitrogen fertilizer accumulation, in order to prevent the diseases caused by calcium deficiency, 0.5%-1% calcium chloride or 0.5% calcium nitrate may be used for foliar dressing, fruit vegetables vegetables from the early flowering stage (Spray celery 3-4 leaves), spray once every 7 days, spray 3 times continuously.

Second, the high concentration of salt hazards

1, symptoms. The dark green color of leaves has a hardened sensation, the leaf of the heart is curled, and the tip of the young leaves and scapes are dry and the plants are dwarfed. There are dark green stripes on the shoulders of tomato fruit, which are obviously different from the color of other parts of the fruit. The growth of the fruit is slow, and plants with severe damage may even show wilting and withering.

2, the reasons for the occurrence. Excessive application of livestock manure or excessive application of ammonium chloride and potassium chloride causes a large accumulation of chloride ions in the tillage layer, causing excessive concentration of soil solution and impeded root growth in the plant, resulting in burning of roots and severely affecting plant growth ( According to the measurement of soil rhizosphere soil EC value of more than 1.8 is likely to occur when the physiological barrier).

3, control methods

(1) Livestock manure should be fully decomposed, and should be thoroughly mixed with the soil during application to avoid single use of chemical fertilizers.

(2) When the concentration of soil solution is too high, the amount of irrigation and times of irrigation should be increased. During the land reclamation, the salt should be drained.

Third, ammonia hazard

1, symptoms. At the beginning of the onset, water immersion occurs between leaf margins or veins. Especially when it is cloudy on a continuous cloudy day, the leaves may appear wilting. After 2-3 days, the affected area became white or brown and dry.

2, the reasons for the occurrence. After the unfermented chicken manure and cake fertilizer are applied, the shed is exposed to high humidity and high temperature. Rapid fermentation produces ammonia hazard crops. In addition, the direct application of ammonium bicarbonate and urea to the soil surface will also produce ammonia gas, which will cause plant leaf damage. If pH test paper is used to draw the water drop test in the shed, pH value >8 can easily cause ammonia hazard.

3, control methods

(1) Organic manure such as chicken manure and cake fertilizer must be fully cooked before being applied. Urea and ammonium bicarbonate should be used in water or buried in soil. Avoid partial nitrogen fertilizers.

(2) Ventilation should be increased before and after fertilization, especially for sheds with existing ammonia hazards. The management of water and fertilizer should be strengthened for the light-vegetable crops that suffered damage, and light curtains should be shaded at noon to promote its recovery.

1, symptoms. Nitrite gas hazards are very likely to occur on a continuous cloudy day. At the beginning of the disease, the leaf margins and tip were immersed in water, and the diseased part was white and dry after 1-2 days. In the event of acute damage, many irregular white lesions appear in the leaves, and even the entire leaf is dry.

2, the cause of the disease. Excessive application of nitrogen fertilizers, poor soil permeability, and low ground temperatures impede the digestion process of nitrogen fertilizers. Nitrite nitrogen is accumulated in large amounts in soil. When the soil is acidic (pH<6=, nitrous oxide gas overflows from the soil, according to When the nitrite gas concentration in the greenhouse is higher than 2mg/kg, it will have a toxic effect on vegetables.

3, control methods

(1) Ventilate immediately and reduce the concentration of nitrous acid gas. (2) Lime is used to neutralize the acidity of the soil and combine with cultivator loose soil to increase the ground temperature.

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