Balling the urea with some clay soil (urea soil, 175:1000) is the most effective method of application which increase the paddy yield by about 9% as a general average. 5.

• 4．尿素作为团球使用（混合比为尿素175对土壤1000），为尿素施肥法中最有效的办法比通常使用法平均增产9%25之效果。