Effects of Organic Fertilizer Replacement Nitrogen Fertilizer on Nitrogen Utilization and Growth of Mung Bean: Evidence from 15N-Tracing Technology

Abstract

To optimize a suitable fertilization method needed for high nitrogen utilization and growth of mung bean in the black soil of Northeast China, a field experiment was carried out with 10 treatments based on isotope-tracing technology. The nitrogen fertilizer utilization, residual, loss and dry-matter transportation, leaf area, photosynthetic potential, and wet-basis moisture content of mung bean were discussed. The results showed that the total utilization rate of nitrogen fertilizer under different treatments was 34.75~47.71%, while in the 0~15 cm soil layer, the total residual rate was 11.36~33.69%, and the loss rate was 21.03~53.89%. The T1 treatment had the lowest total nitrogen fertilizer utilization rate and the greatest loss rate. The leaf area and photosynthetic potential at the seedling stage in the T9 treatment, the branching stage in the T2 treatment, and the flowering stage in the T4 and T9 treatments were 5.11~31.82% higher than those in the CK treatment, and the values at the drumming and maturing stages were significantly lower than those in the CK treatment (p < 0.05). The total wet-basis water content of the root, stem, leaf, and pod in the whole stages compared with the CK treatment increased by 3.35~7.41% in T4, T5, T7, and T8. In the T6 and T9 treatments, the output rate of stem-sheath storage matter and the transformation rate were significantly higher than those in the T1 treatment (p < 0.05). The dry-matter accumulation in the T1 and T9 treatments was significantly different from that in the CK treatment, which increased by 27.72% and 5.10%, respectively. Thus, organic fertilizer coupled with nitrogen fertilizer can improve the nitrogen fertilizer utilization rate and the growth of mung beans.