Growing vegetables in greenhouses generally encounters toxic gas hazards, especially ammonia poisoning occurs most frequently.
Symptoms of poisoning: Vegetables that are more sensitive to ammonia include cucumbers, peppers, tomatoes, eggplants, etc. The affected leaves are waterlogged at the beginning, and then gradually fade to light brown. Young shoots or growth points wilt, in severe cases, the leaf edges are scorched, and the whole plant dies from physiological loss of water and shrinkage.
The causes of greenhouse ammonia are firstly the application of excessive nitrogen fertilizers such as urea, ammonium bicarbonate, ammonium sulfate, etc., the application of organic fertilizers such as human manure and manure and stable manure that are not fully decomposed, and the third is fertilizers such as fermented cake manure or chicken manure in the shed; Fourth, sprinkle fertilizer on the ground during top dressing. It has been determined that when the concentration of ammonia in the air reaches 0.1-0.8%, or when the concentration in the shed reaches 5 mg/L, cucumbers and peppers will soon show harmful symptoms.
In view of the causes of vegetable poisoning caused by ammonia, the main points should be grasped as follows:
First, it is necessary to apply fully decomposed compost, stable manure and human manure to prevent fresh manure from entering the shed;
second, it should be noted that nitrogen fertilizer should not be applied excessively, and phosphorus and potassium fertilizer should be applied;
Third, when vegetables are harmful, 1∶800 times Huimanfeng active liquid fertilizer can be sprayed, which can quickly relieve the poison and restore normal growth.