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确定氮、磷、钾施用比例的田间试验法有两种。一种是直接试验法。此法以适宜的氮用量为基础,使N:P_2O_5:K_2O成1:1:1,2:1:1,3:1:1,2:1:2等等比例布置试验,计算产值和施肥成本看哪种比例经济收益高,即为最佳施用比例。但常因其处理数多,工作量大,难于在农村普遍施行。另一种是三要素抽减试验法。此法只需设置充分施以PK、NK、NP、NPK的4个处理(亦称四项方案),简便易行,农广校学员可在承包地自行试验,故值得推荐。根据4个处理的产量即可计算该土地种该作物时的氮、磷、钾施用比例(见表1)。
There are two field trials to determine the proportion of N, P and K applied. One is the direct test method. Based on the suitable nitrogen content, this method was used to test the ratio of N: P_2O_5: K_2O to 1: 1: 1, 2: 1: 1, 3: 1: 1, 2: 1: What kind of cost to see the high economic benefits, that is, the best ratio. But often because of its handling a large number of heavy workload, it is difficult to implement in rural areas. The other is the three factor reduction test. This method only needs to set up four treatments (also known as four schemes) which are fully implemented with PK, NK, NP and NPK. It is simple and convenient. According to the output of four treatments, the proportion of N, P and K applied to the crop can be calculated (see Table 1).