Korean Journal of Soil Science and FertilizerISSN:0367-6315(Print) 2288-2162(Online)한국토양비료학회

Improving the nitrogen use efficiency (NUE) of crops is a technology that improves crop productivity and prevent environmental pollution simultaneously. A way to improve NUE is to develop and use a controlled release fertilizer. We developed a controlled release fertilizer in terms of controlled-release coated fertilizer for rhizosphere application (CRFR) which is a mineral fertilizer applying just under the plant root zone. In order to test effect of the developed CRFR on crop yield and NUE, field experiments were conducted with six levels of N (N 0, N 190, CRFR-N 16, CRFR-N 22, CRFR-N 27, and CRFR-N 33 kg ha^-1) at the experimental station of Gyeonggi-do Agricultural Research & Extension Services (GARES) for two years (2017 to 2018). The fruit yield and NUE of red pepper were obtained using agronomic measurements. To determine optimum N rate of CRFR we applied linear-plateau model. Results showed that the yield was not significantly different between the two levels of CRFRs (N 22 and 27) and N 190 in 2017. Similarly, the yield was not different between the three levels of CRFRs (N 22 and 27) and N 190 in 2018 although almost six times as much N rate was applied in the N 190. Meanwhile, NUEs in the CRFRs were ranged from 69.8 to 88.5% which were much higher than the N 190 treatment (14.8%). Since CRFRs showed no different yields as compared to N 190, we analyzed the optimum rate of CRFR using the linear plateau model and CRFR applied at 23.1 kg N ha^-1 was optimal for the yield. Our results suggest that CRFR was able to significantly increase crop productivity while reduce environmental pollution because of remarkably high NUE.

Since CRFRs showed no different yields as compared to N 190 (recommended N dose from RDA), we analyzed the optimum rate of CRFR using the linear plateau model, and CRFR applied at 23.1 kg N ha^-1 was optimal for the yield.