近廿年来,在有关养分的有效性方面已取得了重要的进展。本文就其中若干问题作一些探讨。一、土壤测定和作物反应 Ramamoorthy等(1974)在他们的报告中指出,凡土壤K的测定值低于每公顷439公斤时,增施钾肥会造成连续减产。这是一个值得注意的发现,它意味着含K水平低的土壤不应施用钾肥。这是和人们公认的习惯做法相矛盾的。但是根据印度的试验,证明类似的情况并不少见。如在1971—1973年的试验中,土壤含钾水平较高的土壤,施入K_2O Nearly 20 years have seen significant progress on the effectiveness of nutrients. This article discusses some of these issues. Soil Testing and Crop Reactions Ramamoorthy et al. (1974) pointed out in their report that any increase in soil K below 439 kilograms per hectare would result in a continuous cut in production. This is a noteworthy finding, which means that soils containing low levels of K should not be potash. This is in contradiction with accepted practices. However, according to Indian tests, it is not uncommon to find a similar situation. As in the 1971-1973 trial, soils with higher levels of potassium in the soil were applied with K2O