1Central Potato Research Station, Modipuram-250110, (U.P.).
2Central Potato Research Institute, Simla-171001, (H.P.).
3Directorate of Tobacco Development, Madras-600018, (Tamilnadu).
4Central Potato Research Station, Shillong-793009, (Meghalaya).
Field experiments were conducted to study the direct and residual effect of single superphosphate, suphala, basic slag and rockphosphate on the growth and yield of potato (Kufri Jyoti) in acidic brown soil of Shillong during 1976 and 1977. The plant height, weight and number or tubers per plant and tuber yield increased by all the fertilizers except rock phosphate which showed positive effect on tuber yield in a wet year (1977) only. For direct application, superphosphate was the best source of P followed by suphala, basic slag and rockphosphate. However, basic slag showed highest residual effect followed by rockphosphate and super phosphate and suphala. The combined application of 50 kg P2O5 from superphosphate and 100 kg P2O5/ha from rock phosphate was the best for direct as well as residual effect and it proved as effective as 100 kg P2O5/ha from superphosphate.
