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塑膜大棚栽培蔬菜,常因施肥方法不当,忽视通风换气,使棚内有害气体过量蓄积,为害蔬菜,而又常被误诊为病害,导致歉收甚至绝收。一、危害 1.氨气由于施用过量的尿素、硫酸铵等速效化肥;或施肥方法不当,如施得浅、施后浇水不及时;或因施用未经腐熟的有机肥,在棚内高温条件下分解产生氨气,浓度达到5×10~(-6)时,就会为害蔬菜,使叶缘组织出现水渍状斑点,严重时整叶萎蔫枯死。常被误诊为霜老病或其他病症,对氨气敏感的蔬菜有黄瓜、番茄、西葫芦等。 2.亚硝酸气体一次施用铵态氮肥过多,会使某些菌体的作用降低,造成土壤局部酸性。当PH值小于5时,
Plastic film greenhouse cultivation of vegetables, often due to improper methods of fertilization, neglect ventilation, the shed excessive accumulation of harmful gases, harmful vegetables, but often misdiagnosed as disease, leading to poor harvest or even income. First, the hazard 1. Ammonia due to the application of excessive urea, ammonium sulfate and other quick-acting fertilizers; or improper fertilization methods, such as the facilities are shallow, Shi not watering timely; or due to the application of organic fertilizer without maturity, high temperature in the shed Under the conditions of decomposition of ammonia, when the concentration reaches 5 × 10 -6, it will damage vegetables, leaves edge tissue water stain like spots, severe wilting dead leaves. Often misdiagnosed as cream old or other illnesses, sensitive to ammonia vegetables cucumber, tomato, zucchini and so on. 2. A nitrite gas application of ammonium nitrogen fertilizer too much, will reduce the role of some bacteria, resulting in local soil acidity. When the PH value is less than 5,