Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the ￣(15)N mass balancetechnique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated ina f...Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the ￣(15)N mass balancetechnique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated ina field plot experiment. One hundred and thirty-eight kg N/ha, 86 kg N/ha as basal dressing and 52 kgN/ha as top dressing, was applied with band application technique. The experiment was conducted in thesoutheast of China, near Yingtan City, Jianxi Province.Results from is￣(15)N mass balance study showed that when urea was applied as basal dressing the plantrecovery was 44.0% of the applied N for Theatment T (with application of N, P, K, B and lime). Plantrecoveries were 38.0%-40.5% for Treatments -K, -B, -lime and +RS (without application of K, B or limeas well as with additional rice straw compared with Theatment T), which were not significantly differentfrom 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 highup to 71.6% for Theatment -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% forTreatment T when urea was applied as basal dressing, while almost all the applied N was recovered when ureawas applied as top dressing. It was suggested that N loss was greatly controlled by using band applicationmethod in this experiment.Results from the field plot experiment showed that N supply capacity of this red soil was very low, andthe efficiency of the applied N was quite high, 7.1 kg rape seed was increased by application of one kg N forTreatmentT. Nitrogen and phosphorus were the key factors limiting rape yield, and the yield was very lowwhen neither of them was applied. The yield in TreatmentK was significantly lower than that in TYeatmentT, with the former accounting for 77% of the later.展开更多
文摘Fate of urea nitrogen (N) applied to rape grown on a red soil was investigated by the ￣(15)N mass balancetechnique, and efficiency of urea and effect of nutrients balance in raising rape yield were investigated ina field plot experiment. One hundred and thirty-eight kg N/ha, 86 kg N/ha as basal dressing and 52 kgN/ha as top dressing, was applied with band application technique. The experiment was conducted in thesoutheast of China, near Yingtan City, Jianxi Province.Results from is￣(15)N mass balance study showed that when urea was applied as basal dressing the plantrecovery was 44.0% of the applied N for Theatment T (with application of N, P, K, B and lime). Plantrecoveries were 38.0%-40.5% for Treatments -K, -B, -lime and +RS (without application of K, B or limeas well as with additional rice straw compared with Theatment T), which were not significantly differentfrom 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 highup to 71.6% for Theatment -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% forTreatment T when urea was applied as basal dressing, while almost all the applied N was recovered when ureawas applied as top dressing. It was suggested that N loss was greatly controlled by using band applicationmethod in this experiment.Results from the field plot experiment showed that N supply capacity of this red soil was very low, andthe efficiency of the applied N was quite high, 7.1 kg rape seed was increased by application of one kg N forTreatmentT. Nitrogen and phosphorus were the key factors limiting rape yield, and the yield was very lowwhen neither of them was applied. The yield in TreatmentK was significantly lower than that in TYeatmentT, with the former accounting for 77% of the later.
