1Central Potato Research Station, P.O. Model Town, Jalandhar-144 003, (pb.).
2Central Potato Research Institute, Shimla, 171 001, (HP).
*Publication No. 1236, CPRI, Shimla.
Long term effect (17 years) of five intensive crop sequences and manurial treatments was measured on ammonium acetate extractable K content of alluvial soil (Ustochrpt) and tuber yield of potato. The experiment was comprised of five crop rotations (Potato-Wheat-Maize, Potato-Potato-Maize, Potato-Wheat-Paddy, Potato-Potato-Maize-Green manure and Green manure-Potato-Potato-Maize) in the main plot and manurial treatment in the sub plot (44 kg P ha−1, 44 kg P + 83 kg K ha−1 and 30 ton FYM ha−1 (applied once, twice or thrice in 2 years). The recommended dose of N was added to all the crops. The crop rotation having green manure recorded highest available K in soil (90 ppm) and one with paddy showed least (66 ppm). Application of muriate of potash and FYM for 17 years could increase available K in soil from 71 ppm to 77 ppm and 81 ppm respectively. The build up of available K in soil was less than the critical limits of K for potato (115 ppm) established for these soils. The potato crop (cv. Kufri Chandramukhi) following green manuring gave significant more tuber yield (19.4 tonnes ha−1), than that following maize (15.6 tonnes ha−1) and paddy (14.5 tonnes ha−1). The residue of P, PK and FYM significantly increased average tuber yield from 12.5 tonnes ha−1 to 14.3 tonnes ha−1, 15.2 tonnes ha−1 and 17.7 tonnes ha−1 and uptake of K from 54 kg ha−1 to 65 kg ha−1, 72 kg ha−1 and 83 kg−1, respectively. Tuber yield of potato was correlated significantly with available K in soil (r = + 0.668).
