Long-Term Fertilization Effects on Rice Productivity and Nutrient Efficiency in Korean Paddy

ABSTRACT

Long-term fertilization tests evaluated rice (Oryza sativa) productivity in relation to application of nitrogen (N)-phosphorus (P)-potassium (K) (120-34.9-66.7 kg ha^{− 1}, respectively) during 1967–1972 and N-P-K (150-43.7-83.3 kg ha^{− 1}, respectively) during 1973–2000. The comparison treatments (NP, PK, and NK) and the control (not fertilized) were selected for calculating nutrient efficiency. Rice grain yield increased at a 17.78 kg ha^{− 1} yr^{− 1} in the control, mainly due to development of improved cultivars. Phosphorus management was found to be important for indigenous fertility and rice productivity in this paddy soil. Yield increased significantly with P fertilization. Without N fertilization (PK), rice productivity increased 56.85 kg ha^{− 1} yr^{− 1} from 62% of NPK at the initial stage to 74% after passing 34 years, which might be affected by increasing biological N fixation with P accumulation in soil. In NK treatment, rice yield increased at a relatively low rate (37.82 kg hr^{− 1} yr^{− 1}) from the same rice productivity with that of NPK in 1967 to 91% after 34 years. In comparison, yield increased at a high rate (62.82 kg hr^{− 1} yr^{− 1}) without K fertilization (NP) from ca. 90% of NPK and might exceed the yield of NPK after 64 years of long-term fertilization. Therefore, K fertilization level might be readjusted after long-term fertilizing in paddy soil.

Keywords:

• Long-term fertilization
• rice
• nutrient uptake
• nutrient efficiency
• paddy soil

ACKNOWLEDGMENTS

C. H. Lee is supported by scholarships from the BK21 Program, Ministry of Education & Human Resource Development, Korea. We greatly appreciate the staff in Yeongnam Agricultural Research Institute (YARI) who have contributed to the mission and maintained the long-term fertilized paddy soil, and made it a valuable resource to several generations of past, present and future researchers.

Notes

*Nutrient efficiency of N, P, and K recovery from applied fertilizers was determined by the expression: R = (C_f-C_c) × 100/C, where R = % of recovered N, P and K; C_f = absorbed N, P and K by the rice for NPK plot; C _c = absorbed N, P and K for PK, NK and NP plots, respectively, and C = total amount of N, P and K applied to NPK plot.