Abstract
Rice is grown in different ecosystems and requires suitable management strategies for sustainable production. Two field experiments were conducted at the experimental farm of IRRI, Philippines to evaluate different crop establishment methods and N management strategies in relation to crop yield and resource-use efficiency. In the first experiment, grain yield across establishment methods was statistically similar although transplanting method had numerically higher yield than the direct seeding methods. Transplanting method, however, required more water and therefore had numerically lower water use efficiency than the direct-seeding method. The different indices of nitrogen utilization efficiency did not significantly vary across establishment methods during the wet season but the dry seeding method had the lowest nitrogen recovery efficiency during the dry season. The amount on nitrogen applied based on the SPAD readings was lower by 15 and 40 kg ha1, respectively than the standard N management strategy. Agronomic N-use efficiency and recovery efficiency were significantly higher in the SPAD-based nitrogen management strategy than in the other strategies during the dry season. Nitrogen balance was highest (115 kg ha1) in the dry seeding method and lowest (48 kg ha1) in the transplanting method. A similar trend of results was observed during the dry season.