Abstract
The effect of nitrogen, phosphorus and potassium on the yield and economic return in seed potato production was studied at different locations of Bangladesh during 1996-97 to 1998-99. A significant variation among the doses of nitrogen was noticed both at the Bangladesh Agricultural University (BAU) and Rural Development Academy (RDA) farms during 1996-97. Application of 175 kg N/ha in the form of urea gave the highest yield of seed tubers (26.87 and 20.32 t/ha at BAU and RDA, respectively). Maximum yield of seed tubers was obtained with 60 kg P2O5/ha in the form of triple superphosphate (TSP) at BAU (23.81 t/ha) and with 100 kg P2O5/ha at RDA (17.64 t/ha). Application of 125 kg K2O/ha in the form of muriate of potash (MP) gave the highest yield of seed tubers at BAU (25.47 t/ha) and 150 kg K2O/ha gave the highest seed yield (17.07 t/ha) at RDA. In 1997-98, at BAU, when the haulms were cut at 90 DAP, application of 125-50-175 kg N, P2Os, K2O/ha among 36 NPK combinations gave the highest yield of seed tubers (37.58 t/ha) with the maximum economic return (BCR=2.95); and at RDA, 150- 75-175 kg N, P2O5, K2O/ha gave the highest yield of seed tubers (34.58 t/ha) with the maximum BRC (2.68). During 1998-99, at BAU, the combination of 125-50-175 kg N, P2O5, K2O/ha among selected 6 NPK combinations gave the highest yield of seed tubers (30.46 t/ha) with maximum BCR (2.33). The yield trials at the farmers' field with the same 6 NPK combinations conducted in Jamalpur (BADC's contract growers zone) and Bogra (BADC's contract growers zone) showed that 175-25-150 kg N, P2O5, K2O/ha gave the highest yield of seed tubers (31.39 and 32.65 t/ha respectively), with maximum economic return having BCR 2.41 and 2.47 at Jamalpur and Bogra respectively. In the yield trial conducted in Thakurgaon (private sector seed production farm) the combination of 150-75-175 kg N, P2O5, K2O/ha gave the highest yield of seed tubers (33.22 t/ha) with a maximum economic return (BCR=2.51). The results of the experiments conducted at BAU, RDA and farmers' field during 1996-97 to 1998-99 clearly indicate that the locations had significant effect on the yield of seed tubers as influenced by NPK combinations. The study demonstrated that for a specific location, a specific dose of fertilizer is needed for maximum yield and economic return in seed potato production.