一怎样追肥追肥是一件比较复杂的事情。什么时候施用追肥?该用多少,怎样施用?这些问题都得看作物的种类、作物生长的情况以及肥料的数量等等条件来决定。这里,只打算谈谈施用追肥时应该注意的几项原则:首先,要适时施用。追肥过早或过晚都是不适合的。追肥过早,效果不大。追肥过晚,起不了作用;特别是施用氮肥过晚,容易使作物贪青,徒长,延迟成熟,影响农产品质量。所以说,肥料要追施在火候上,就是这个道理。各种作物需肥的时期是不同的,所以要注 How to top-dressing is a more complicated thing. When to use top dressing? How much, how to use? These problems have to be depending on the crop species, crop growth and fertilizer quantity and other conditions to decide. Here, I only intend to talk about several principles that should be paid attention to when applying top-dressing: First, it is necessary to apply it in time. Dressing too early or too late are not suitable. Dressing too early, little effect. Fertilizer too late, can not play a role; especially the application of nitrogen fertilizer too late, easy to crop greedy, leggy, delayed maturity, affecting the quality of agricultural products. So, fertilizer to be chased in the heat, is the truth. Different crops need different periods of fertilization, so be careful