A long-term fertilization experiment with monoculture corn (Zea mays L.) was established in 1980 on a clay-loam soil (Black Soil in Chinese Soil Classification and Typic Halpudoll in USDA Soil Taxonomy) at Gongzhuling, Jilin Province, China. The experiment aimed to study the sustainability of grain-corn production on this soil type with eight different nitrogen (N)-, phosphorus (P)-, and potassium (K)-mineral fertilizer combinations and three levels (0, 30, and 60 Mg ha/1y) of farmyard manure (FYM). On average, FYM additions produced higher grain yields (7.78 and 8.03 Mg/ha) compared to the FYM0 (no farmyard application) treatments (5.67 Mg/ha). The application of N fertilizer (solely or in various combinations with P and K) in the FYM0 treatment resulted in substantial grain-yield increases compared to the FYM0 control treatment (3.56 Mg/ha). However, the use of NP or NK did not yield in any significant additional effect on the corn yield compared to the use of N alone. The treatments involving P, K, and PK fertilizers resulted in an average 24 per cent increase in yield over the FYM0 control. Over all FYM treatments, the effect of fertilization on corn yield was NPK > NP = NK = N > PK = P > K = control. Farmyardmanure additions for 25 y increased soil organicmatter (SOM) content by 3.8 g/kg (13.6%) in the FYM1 treatments and by 7.8 g/kg (27.8%) in the FYM2 treatments, compared to a 3.2 g/kg decrease (11.4%) in the FYM0 treatments. Overall, the results suggest that mineral fertilizers can maintain high yields, but a combination of mineral fertilizers plus farmyard manure are needed to enhance soil organic matter levels in this soil type.