Nitrogen recovery and nitrogen use efficiency of potatoes in an integrated compost fertilization system in an Andosol soil

The effects of composts in a potato production system were analyzed in terms of growth, yield, nitrogen recovery, and nitrogen use efficiencies. Increasing chemical fertilizer (CF) costs have seen farmers applying less than the recommended amounts. Swine manure and poultry manure (PM) composts were used here as nitrogen sources to construct a sustainable low chemical fertilizer input production system. The amended plotsRSQUO total and marketable tuber yields were equal to or higher than those of the 100% CF (CF100) plot. Nitrogen recovery efficiencies of the compost-amended plots were not significantly different from that of the CF100 plot (18.4%). Agronomic nitrogen use efficiency was different among plots, and the highest was with the 25% PM (PM25) plot (183 kg kg^-1). There were significantly high internal nitrogen use efficiencies (IE_N) in more than half of the amended plots compared with the CF100 plot. Partial factor productivity (PFP) was the highest in the PM25 plot (233 kg kg^-1). Productivity in the amended plots was higher than in the CF100 plot. IE_N and PFP were indices with significant differences in this study. Composts, specifically PM at its various integration levels, had higher IE_N than the CF100 plot and could be candidates for reducing CF input.