Monitoring the Potassium Fertility Levels of Four Soil Series from Northern India over a Period of Time

The changes in K fertility levels were studied in intensively cultivated farmers' fields of four soil series from northern India. According to soil test rating, no appreciable change was observed in available and reserve K status over a period of seven years in Lukhi, Nabha, Khatki and Rarha soils, but their average contents, particularly of reserve K and modal class of available K increased markedly in all the soil series. However, the influence of texture was not prominent on the changes in different forms of K in the soil. Though, the need to modify the K fertilizer uses according to the cropping pattern was reflected in most of the soil series to sustain crop productivity, the intervening period was not large enough to monitor the K fertility levels in these soil series.