ABSTRACT There is need for information on the general crop physiology and nitrogen (N) fertiliser responses of beetroot in New Zealand. We investigated the responses to N of beetroot grown in a silt loam near Hastings, Hawke’s Bay. Four fertiliser treatments (0, 160, 320 or 480 kg N ha−1) were applied as urea, split evenly over four application times. The canopy light extinction coefficient averaged 0.64. Radiation use efficiency averaged 1.05 g MJ−1 for the treatments that received N fertiliser. Maximum yield occurred at an N fertiliser rate around 320 kg N ha−1. Published recommendations suggest only 225 kg N ha−1 would have been needed. This underestimation would have led to a yield penalty of only about 6%, but decreased the risk of significant mineral being N left in the soil. We discuss approaches to account for N supply from the soil when forecasting residual mineral N and N leaching risk.

中文翻译：

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甜菜根 (Beta vulgaris L.) 的生长和对氮供应的反应——案例研究

摘要 需要了解新西兰甜菜根的一般作物生理学和氮 (N) 肥料反应的信息。我们调查了对种植在霍克斯湾黑斯廷斯附近淤泥壤土中的甜菜根 N 的反应。四种肥料处理（0、160、320 或 480 kg N ha-1）作为尿素施用，在四次施用期间均匀分配。冠层消光系数平均为 0.64。对于接受氮肥的处理，辐射利用效率平均为 1.05 g MJ-1。最大产量发生在氮肥施用量约为 320 kg N ha-1 时。已发表的建议表明只需要 225 kg N ha-1。这种低估会导致仅约 6% 的产量损失，但降低了土壤中留下重要矿物质 N 的风险。