Integrated Nutrient Management for Sustainable Crop Production in Potato-Sunflower Sequence

A field experiment was conducted for three years to compare farmyard manure (FYM) with legume and non-legume green manures at different levels of fertilizer nitrogen in potato (Solanum tuberosum)-sunflower (Helianthus annuus) sequence. Farmyard manure and green manures [sesbania (Sesbania aculeate), pearl millet (Pennisetum typhoidium) and sesbania + pearl millet] were incorporated before planting of potato crop. Five levels of fertilizer N, i.e., 0 (N(0)), 60 (N1), 120 (N2), 180 (N3) and 240 kg N ha-1 (N4) were applied to potato. Residual effect of organic manures was studied on following sunflower at three levels of fertilizer N (0, 30 and 60 kg N ha-1). Incorporation of inorganic manures improved organic C, available P and available K content in soil after three years in potato-sunflower sequence. Among the various organic manures, the highest potato tuber yield was recorded in FYM treatment. The response to N application was observed up to180 kg N ha-1, irrespective of organic manure treatment. The contribution of larger size (> 4.5 cm) potato tubers towards yield increased with fertilizer N and was 13.0, 17.9, 23.1, 24.4 and 26.7 percent with N(0), N1, N2, N3 and N4 at 90 days after planting (DAP). However, the contribution of smaller size tubers (< 3.5 cm) was in the order of N(0) > N1 > N2 > N3 > N4. The percentage contribution of larger size tubers towards yield was more in FYM plots than other organic manures. The increase in N uptake with organic manures over non-manured treatment was 51.6, 27.8, 27.1 and 6.2 percent with FYM, sesbania, sesbania + pearl millet and pearl millet, respectively. Organic manures had significant residual effect on seed yield, growth and phenology of sunflower, the response to FYM being more than green manures. Fertilizer N application up to 60 kg ha-1 to sunflower also improved seed yield, plant growth and prolonged grain filling period.