目前,以尿素为主的速效氮肥仍然是农业生产上重要的丰产因素之一,而且,在今后较长的历史时期内,它所占有的地位也不会动摇。但是我国在使用上长期存在着供氮期短、利用率低、施用方法不科学等问题。针对这些问题国内外有关专家不断地进行多方面探索和研究。近年来,缓释/控释肥? Currently, available urea, mainly nitrogen, is still one of the most important productivity factors in agricultural production. Moreover, its position in the long history will not be shaken. However, there is a long-term shortage of nitrogen supply in our country, with low utilization rates and unscientific application methods. In response to these problems, relevant experts at home and abroad continue to conduct various exploration and research. In recent years, sustained release / controlled release fertilizer?