Nitrogen management in sweet potato (Ipomoea batatas) under rainfed conditions

A field experiment was conducted during the rainy reason of 1999 and 2000 on sandy-loam soil of Agricultural College, Tirupati, under rainfed conditions to study the effect of integrated nitrogen-management practices on the yield of sweet potato (Ipomoea batatas L.). The investigation revealed that an integrated use of 50% N through fertilizer + 50% N through pig manure resulted in the highest yield owing to higher yield attributes coupled with higher utilization and harvest indices. However, The maximum net returns as well as benefit: cost ratio were obtained with the application of 50% N through fertilizer + 50% N through poultry manure due to lesser cost per unit of nutrients (poultry manure contains more N, P₂O₅ and K₂O than farmyard manure and pig manure). In general, higher yield, net returns and benefit: cost ratio were obtained with the conjunctive use of 50% N through fertilizers and 50% N through any of the organic manures (F N₅₀; + PGM N₅₀; FN₅₀; + FYM N₅₀; F N₅₀ + PLM₅₀) compared with other nitrogen-management practices.