答:因为尿素的吸湿性很强,易造成种子生理失水;另外,尿素里含有缩二脲,对种子里的蛋白质代谢有毒害作用。这些,均可影响种子萌发或出苗,所以一般教科书都说尿素不能作种肥。但是,据我们掌握的情况看来,在没有其他氮肥的情况下,生产中也能用尿素作种肥。欲使其不发生肥害,必须掌握好施用方法,一是亩用量不超过8～10斤,二是肥、种之间一定要有土相隔。这两点互为条件,缺一不可。山东省是以冬麦—— A: Because of the strong hygroscopicity of urea, easy to cause physiological water loss of seeds; In addition, biuret contains urea, the seeds of protein metabolism toxic effect. These can affect seed germination or emergence, so generally textbooks say urea can not be used as seed fertilizer. However, as far as we know, it appears that urea can be used as a seed fertilizer in production without other nitrogenous fertilizers. To make it fat and fat, must master the application method, first, the amount of mu does not exceed 8 to 10 pounds, and second, fertilizer, there must be separated from the soil. These two conditions each other, are indispensable. Shandong Province is winter wheat -