Pedosphere 5(2): 107--114, 1995
ISSN 1002-0160/CN 32-1315/P
©1995 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Fate of urea nitrogen applied to rape grown on a red soil and efficiency of urea in raising rape yield |
| CAI Gui-Xin1, PENG Guang-Hao1, WU Yi-Wei2, MA Mao-Tong1, GAN Shou-Wen3 and MEN Ci-Fu2 |
1 Institute of Soil Science, Academia Sinica, Nanjing 210008 (China);
2 Zhejiang Academy of Agricultural Sciences, Hangzhou 310021 (China);
3 Chinese Academy of Agricultural Sciences, Beijing 100081 (China) |
| ABSTRACT |
| Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the 15N mass balance technique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated in a field plot experiment. One hundred and thirty-eight kg N/ha, 86 kg N/ha as basal dressing and 52 kg N/ha as top dressing, was applied with band application technique. The experiment was conducted in the southeast of China, near Yingtan City, Jianxi Province. Results from 15N mass balance study showed that when urea was applied as basal dressing the plant recovery was 44.0% of the applied N for Treatment T (with application of N, P, K, B and lime). Plant recoveries were 38.0%-40.5% for Treatments -K, -B, -lime and +RS (without application of K, B or lime as well as with additional rice straw compared with Treatment T), which were not significantly different from Treatment T. In contrast, plant recovery was only 5.1% for Treatment -P (without application of P), indicating that P was the factor limiting N uptake by rape. However, N remaining in 0-0.30 m soil was high up to 71.6% for Treatment -P, while the corresponding data were 33.0%-42.6% for the other treatments. The total recovery of applied N (including plant recovery and N remaining in 0-0.60 m soil) was 91.5% for Treatment T when urea was applied as basal dressing, while almost all the applied N was recovered when urea was applied as top dressing. It was suggested that N loss was greatly controlled by using band application method in this experiment. Results from the field plot experiment showed that N supply capacity of this red soil was very low, and the efficiency of the applied N was quite high, 7.1 kg rape seed was increased by application of one kg N for Treatment T. Nitrogen and phosphorus were the key factors limiting rape yield, and the yield was very low when neither of them was applied. The yield in Treatment -K was significantly lower than that in Treatment T, with the former accounting for 77% of the later. |
| Key Words: fate of urea-N, N loss, rape yield, red soil |
| Citation: Cai, G. X., Peng, G. H., Wu, Y. W., Ma, M. T., Gan, S. W. and Men, C. F. 1995. Fate of urea nitrogen applied to rape grown on a red soil and efficiency of urea in raising rape yield. Pedosphere. 5(2): 107-114. |
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