Best management practices for N fertilization should increase yields while reducing negative environmental effects such as losses by ammonia (NH₃) volatilization and emission of greenhouse gases, especially nitrous oxide (N₂O). We studied the impact on sugarcane of two N sources (UR: urea and CAN: calcium ammonium nitrate) in three N rates (30, 60, and 90 kg N ha⁻¹ in the plant cane cycle and 60, 120, and 180 kg N ha⁻¹ in ratoons) on a sugarcane field grown on a Red Latosol soil in southeastern Brazil. We measured sugarcane yields and N₂O, CO₂ and CH₄ emissions in three crop cycles (plant cane, 2nd and 3rd ratoons), and NH₃ in two crop cycles (2nd and 3rd ratoons). The accumulated emission of N₂O from UR was significantly higher in comparison with those of CAN in all three crop cycles. The average emission factors for UR were 0.8% (plant cane), 1.1% (2nd ratoon) and 0.8% (3rd ratoon) and the corresponding figures for CAN were 0.4%, 0.7% and 0.5%, respectively. The N₂O intensity was higher for UR (20.3 mg N–N₂O kg⁻¹ sugarcane stalk) than CAN (16.2 mg N–N₂O kg⁻¹ sugarcane stalk). The NH₃ volatilization losses for CAN were less than 1% compared to 5–16% of the N applied as UR. Stalk yield increased with N application, but no difference was observed between UR and CAN. We concluded that CAN has the potential to reduce both NH₃ and N₂O losses compared with urea and is the preferred N source for sugarcane.

中文翻译：

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氮源和施用量影响甘蔗中N 2 O和NH 3的排放

氮肥的最佳管理方法应增加产量，同时减少负面的环境影响，例如氨（NH ₃）挥发造成的损失以及温室气体，特别是一氧化二氮（N ₂ O）的排放。我们研究了三个N比例（30、60和90 kg N ha ^-1在植物甘蔗循环中以及60、120和180 kg N比例）对两种氮源（UR：尿素和CAN：硝酸钙铵）对甘蔗的影响。在巴西东南部的红色Latosol土壤上生长的甘蔗田上，在再生区中的N ha ^-1）。我们测量了三个作物周期（甘蔗，第2和第3再生棉）和NH _3的甘蔗产量以及N ₂ O，CO ₂和CH ₄排放在两个作物周期（第2和第3再生区）中。在所有三个作物周期中，来自UR的N ₂ O累积排放量均显着高于CAN。UR的平均排放因子为0.8％（植物藤），1.1％（第二藤）和0.8％（第三藤），而CAN的相应排放量分别为0.4％，0.7％和0.5％。UR（20.3 mg N–N ₂ O kg ^-1甘蔗茎）的N ₂ O强度高于CAN（16.2 mg N–N ₂ O kg ^-1甘蔗茎）。NH ₃CAN的挥发损失小于1％，而用作UR的氮的挥发损失为5-16％。氮肥的施用增加了秸秆的产量，但是在UR和CAN之间没有发现差异。我们的结论是，与尿素相比，CAN具有降低NH ₃和N ₂ O损失的潜力，并且是甘蔗的首选N源。