The increasing demand for food production has led to a tenfold increase in nitrogen (N) fertilizer use since the Green Revolution. Nowadays, agricultural soils have been turned into high-nitrifying environments that increase N pollution. To decrease N losses, synthetic nitrification inhibitors (SNIs) such as 3,4-dimethylpyrazole phosphate (DMPP) have been developed. However, SNIs are not widely adopted by farmers due to their biologically limited stability and soil mobility. On the other hand, allelopathic substances from root exudates from crops such as sorghum are known for their activity as biological nitrification inhibitors (BNIs). These substances are released directly into the rhizosphere. Nevertheless, BNI exudation could be modified or even suppressed if crop development is affected. In this work, we compare the performance of biological (sorghum crop) and synthetic (DMPP) nitrification inhibitors in field conditions. Sorghum crop BNIs and DMPP prevented an increase in the abundance of ammonia-oxidizing bacteria (AOB) without affecting the total bacterial abundance. Both nitrification inhibitors maintained similar soil NH4+ content, but at 30 days post-fertilization (DPF), the sorghum BNIs resulted in higher soil NO3− content than DMPP. Even so, these inhibitors managed to reduce 64% and 96%, respectively, of the NO3−-N/NH4+-N ratio compared to the control treatment. Similar to soil mineral N, there were no differences in leaf δ15N values between the two nitrification inhibitors, yet at 30 DPF, δ15N values from sorghum BNI were more positive than those of DMPP. N2O emissions from DMPP-treated soil were low throughout the experiment. Nevertheless, while sorghum BNIs also maintained low N2O emissions, they were associated with a substantial N2O emission peak at 3 DPF that lasted until 7 DPF. Our results indicate that while sorghum root exudates can reduce nitrification in field soil, even at the same efficiency as DMPP for a certain amount of time, they are not able to prevent the N pollution derived from N fertilization as DMPP does during the entire experiment.

中文翻译：

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抑制非耕作地中海土壤硝化作用的生物和合成方法

自绿色革命以来，对粮食生产的需求不断增加，导致氮 (N) 肥料的使用量增加了 10 倍。如今，农业土壤已变成高硝化环境，增加了氮污染。为了减少氮损失，已经开发了合成硝化抑制剂 (SNI)，例如 3,4-二甲基吡唑磷酸盐 (DMPP)。然而，由于 SNI 的生物学稳定性和土壤流动性有限，农民并未广泛采用。另一方面，高粱等作物根系分泌物中的化感物质因其作为生物硝化抑制剂 (BNI) 的活性而闻名。这些物质直接释放到根际。然而，如果作物发育受到影响，BNI 渗出可能会被改变甚至抑制。在这项工作中，我们比较了生物（高粱作物）和合成（DMPP）硝化抑制剂在田间条件下的性能。高粱作物 BNI 和 DMPP 在不影响总细菌丰度的情况下阻止了氨氧化细菌 (AOB) 丰度的增加。两种硝化抑制剂保持相似的土壤 NH4+ 含量，但在施肥后 30 天 (DPF)，高粱 BNI 导致土壤 NO3− 含量高于 DMPP。尽管如此，与对照处理相比，这些抑制剂设法分别降低了 64% 和 96% 的 NO3--N/NH4+-N 比率。与土壤矿物质 N 相似，两种硝化抑制剂的叶片 δ15N 值没有差异，但在 30 DPF 时，高粱 BNI 的 δ15N 值比 DMPP 的更正。在整个实验过程中，DMPP 处理过的土壤中的 N2O 排放量很低。尽管如此，虽然高粱 BNI 也保持了低 N2O 排放，但它们与持续到 7 DPF 的 3 DPF 处的大量 N2O 排放峰值有关。我们的结果表明，虽然高粱根系分泌物可以减少田间土壤中的硝化作用，即使在一定时间内以与 DMPP 相同的效率，它们也不能像 DMPP 在整个实验过程中那样防止由施氮引起的氮污染。