Causes and prevention of vegetable fat damage
Ammonia poisoning. In recent years, it has often occurred in the production of greenhouses in winter. The damage of ammonia poisoning is divided into two types: traumatic type and internal injury type. The traumatic hazard is mainly caused by damage to the leaves of the seedlings, and the leaf margin tissue turns brown first, then becomes white, and water-stained spots appear first around the leaves, and die in severe cases.
The internal injury type hazard is generally caused by a large amount of ammonium nitrogen fertilizer applied at one time, the soil solution concentration is too high, the nutrients absorbed by the vegetables are blocked, the cell permeation resistance is increased, and the reverse osmosis phenomenon is serious, the root water loss becomes brown, and the leaves turn yellow. Different vegetable varieties have different resistance to ammonia. Most vegetable seedlings are harmed when the ammonia gas reaches 5 mg/L. Tomato, pepper and pakchoi seedlings are sensitive, while eggplant reflects poor ammonia gas and ammonia concentration. Symptoms are only shown at 40 mg/L. Generally, the pH of the small water droplets attached to the inner wall of the greenhouse or the arch shed is above 7.2, which can indicate the symptoms of ammonia poisoning. Therefore, the test can be carried out with PH test paper.
Because winter ventilation in the shed is poor, winter vegetables are prone to fat and gas damage. In view of the reasons for the fertilizer damage caused by farmers in the past few years, the main reasons are as follows: application of excessive ammonium fertilizer; application of organic fertilizers such as insufficiently fermented manure and bean cake; application of urea or ammonium bicarbonate in the shed; soil drying The ventilation is not timely.
Although the fat damage is not a disease, once it happens, if it is not handled properly, it can be completely destroyed in 1-2 days, and the damage caused is distressing.
Control measures: watering in time, the soil should not be too dry, keep it moist, see watering when it is dry. Some vegetable farmers are controlling the seedling period, control the water over the head, and are prone to ammonia poisoning. In the seedling stage, combined with watering, it can be sprayed to help maintain the culture. Do not apply fertilizer in the shed, apply the soil deeply, and apply water after application. The applied organic fertilizer is applied after being fully decomposed. Do not overdose ammonium and ammonium nitrate fertilizers, and apply a small amount of fertilizer. Under the condition of ensuring the temperature of the seedlings, open the window as much as possible to ventilate and reduce the ammonia in the shed. Fertilization occurs, watering in time, the leaf surface can be sprayed with “Tianda 2116†or compound microbial fertilizer 500 times liquid, or “Fugen†300 times liquid for root irrigation, the effect is better.