EFFECT OF'CHEMICAL FERTILIZER ON YIELD OF POTATO (Soianum tuberosum L.) IN THE UPCOUNTRY WET ZONE OF SRI LANKA

摘要

A field experiment was carried at the Agricultural Research Station at Slta Eliya to find out the single and combined effect of nitrogen (N), phosphorus (P) and potassium (K) on potato tuber yield. Twenty seven treatments compromising of three N levels (viz. 0,100 and 200 kg ha~(-1)), three P_2O_5 levels, (0, 125 and 250 kg ha~(-1)) and three K_2O levels (0, 100 and 200 kg ha~(-1)) were examined using experimental design of 3~3 confounded. Increase In potato tuber weight with the application of NP and K varied from season to season. Irrespective of the nutrient, weight difference between zero application and the highest level of application was significant In all the seasons. Significant weight Increase for each Increment of nutrient up to the highest level was observed only for potassium In all seasons. Weight Increase due to K application depended on the level of the N and P application. When the N and P applications were higher, high levels of potassium gave significantly higher potato tuber weight. Therefore, application of 200 kg K_2O ha~(-1) with P_2O_5 at 250 kg ha~(-1) and N at 200 kg ha~(-1) was found to be the most suitable combinations to get a maximum potato tuber weight.