Knowing the influence of long-term N fertilization is a key aspect in improving the yield of most crops, including sugarcane (Saccharum spp.). We aimed to assess the effect of N-fertilizer sources and rates on sugarcane yield, biomass partitioning, juice quality, nutrient accumulation, and N efficiency in acid soils. Two field experiments were carried out in southeastern Brazil for consecutive five years. Six N-fertilizer managements [ammonium nitrate and urea at a rate of 100 kg N ha^− 1 (AN100 and UR100, respectively), calcium ammonium nitrate at a rate of 50, 100, 150, and 200 kg N ha^− 1 (CAN50, CAN100, CAN150, and CAN200, respectively)] were applied to acidic soils. Nitrogen fertilization did not affect sugarcane and sugar yields at the site with previous rotation with peanut (Arachis hypogea) before crop replanting. Conversely, at the site under continuous monoculture, AN100, CAN100, and CAN150 showed increases of 7–25% in sugarcane and sugar yields, and 3–7% in Brix and recoverable total sugar content. We conclude that in responsive sites, fertilizer N additions improve crop yield and juice quality, although high N inputs in the long term (> 100 kg N ha^− 1) can reduce sugarcane sustainability. Similarly, non-responsive sites can exhibit substantial economic losses and environmental pollution. Identifying responsive and non-responsive sites to fertilizer N is required for improving N use efficiency and reducing environmental risks and economic losses.

中文翻译：

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氮肥对热带酸性土壤中甘蔗生长，营养状况和生产力的影响

了解长期氮肥的影响是提高包括甘蔗（Saccharum spp。）在内的大多数农作物产量的关键方面。我们旨在评估氮肥来源和比率对酸性土壤中甘蔗产量，生物量分配，汁液质量，养分积累和氮效率的影响。连续五年在巴西东南部进行了两次野外试验。六种氮肥管理方案：硝酸铵和尿素的比例为100 kg N ha ^-1（分别为AN100和UR100），硝酸钙铵的比例为50、100、150和200 kg N ha ^-1（分别为CAN50，CAN100，CAN150和CAN200）]应用于酸性土壤。在作物重新种植之前，先用花生（花生）进行轮作，施氮不会影响甘蔗和蔗糖的产量。相反，在连续单一栽培的地方，AN100，CAN100和CAN150的甘蔗和糖产量增加了7–25％，白利糖度和可回收的总糖含量增加了3–7％。我们得出的结论是，尽管长期高氮输入（> 100 kg N ha ^-1），但在高响应地区，氮肥的添加可以提高作物产量和果汁质量。）会降低甘蔗的可持续性。同样，无响应的站点可能会显示出巨大的经济损失和环境污染。为了提高氮素的利用效率，减少环境风险和经济损失，需要确定对肥料氮有反应和无反应的场所。