南京郊区大白菜生长期氮素的供应及利用

在南京郊区露地生产条件下,研究了不同施肥处理秋季大白菜生长期的土壤N素供应、作物养分吸收利用和肥料N素损失。结果表明,在大白菜整个生育期,耕层土壤供N量为50.7kg/hm2,占土壤全N量的1.07%。作物收获期地上部分生物量和N素含量随施N量的提高而升高,施用N肥显著增加了大白菜的生物量,提高幅度高达3~4倍。植株吸收N量70%以上来源于肥料N。在本试验条件下,尿素N肥表观利用率为26%~35%,土壤NO3--N含量随N肥施用量的增加而升高,主要累积在0~40cm土层中。

N Supply and N Recovery by Chinese Cabbage During the Growing Period in Nanjing Suburbs

A field experiment was conducted on Chinese cabbage in Nanjing suburbs to investigate soil nitrogen supply, nutrient uptake by the vegetable and chemical N losses during its growing period. Results showed that the amount of N supplied to the crop by the soil in the 0 ~ 20 cm layer was 50.7 kg/hm2, accounting for 1.07% of the total soil N in the layer. Application of N fertilizer significantly increased yield of Chinese cabbage by 3 ~ 4 times. More than 70% of the N taken up by Chinese cabbage was derived from chemical N fertilizer. In the field experiment, the apparent recovery rate of urea was 26% ~ 35%. Nitrate content in the 0 ~ 40 cm soil profile increased with N application rate.