The over-use of synthetic nitrogen (N) fertilisers for crop production can cause environmental pollution through leaching and gaseous losses, resulting in low N use efficiency (NUE). Previous work has shown that brown coal (BC) combined with urea can slow down the fertiliser-N release to better synchronise soil N supply with crop N demand. The study aimed to evaluate the impact of granulated BC-urea (BCU) applied to sweet corn on NUE, fate and recovery of fertiliser-N using an ¹⁵N tracer technique. In this in-field microcosm study, 10 atom percent enriched ¹⁵N-labelled urea (46% N) and BCU (20% N) were applied as N fertilisers at rates of 90 or 180 kg N ha⁻¹. On average, BCU fertiliser reduced the urea-derived ¹⁵N losses as nitrous oxide (N₂O) by 64%, ammonia (NH₃) by 73% and downward movement of total N by 59% compared to urea. Reduced losses of applied BCU fertiliser-¹⁵N were associated with significantly increased microbial immobilisation, soil retention and availability of fertiliser-¹⁵N to plants for longer periods of time, compared with urea. As a result, BCU enhanced cob yield by an average of 23%, ¹⁵N uptake by 21% and fertiliser NUE by 21% over urea. The plant recovery of fertiliser-¹⁵N was significantly higher from BCU (59%) than the recovery from urea (38%). Moreover, mining of native soil-N was lower when the N-fertiliser source was BCU cf. urea, suggesting that BCU could be used as a more N-efficient alternative to urea in cropping systems.

中文翻译：

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在田间微观世界中用作缓释褐煤尿素的氮的归宿和回收：15N 示踪剂研究

在作物生产中过度使用合成氮 (N) 肥料会通过淋溶和气态损失造成环境污染，从而导致氮利用效率 (NUE) 低下。以前的工作表明，褐煤 (BC) 与尿素结合可以减缓肥料 N 的释放，从而更好地使土壤 N 供应与作物 N 需求同步。该研究旨在使用¹⁵ N 示踪技术评估施用于甜玉米的颗粒状 BC-尿素 (BCU) 对 NUE、归宿和肥料 N 回收率的影响。在此田间微观世界研究中，以 90 或 180 kg N ha ^-1的比率施用10 原子百分比富集的¹⁵ N 标记尿素 (46% N) 和 BCU (20% N) 作为氮肥。平均而言，BCU 肥料减少了尿素衍生的¹⁵与尿素相比，N 以一氧化二氮 (N ₂ O) 的形式损失了 64%，氨 (NH _{3 ) 损失了 73%，总 N 向下移动了 59%。}与尿素相比，施用 BCU 肥料 - ^{15 N 的损失减少与显着增加的微生物固定化、土壤保持力和肥料 - 15} N 对植物的可利用性更长时间有关。结果，与尿素相比，BCU 将玉米芯产量平均提高了 23%，¹⁵ N 吸收量提高了 21%，肥料 NUE 提高了 21%。^{BCU 中15} N肥料的植物回收率(59%) 显着高于尿素 (38%) 的回收率。此外，当 N 肥料来源为 BCU 时，原生土壤 N 的开采量较低。尿素，这表明 BCU 可以在种植系统中用作尿素的氮高效替代品。