University of Cologne, Institute of Zoology, Department of Biology, Germany.
Institute of Soil Research, Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences (BOKU), Peter Jordan Straße 82, 1190 Vienna, Austria; Institute of Agronomy, Department of Crop Sciences, University of Natural Resources and Life Sciences (BOKU), Konrad Lorenz-Straße 24, 3430 Tulln an der Donau, Austria.
Sci Total Environ. 2023 Apr 20;870:162007. doi: 10.1016/j.scitotenv.2023.162007. Epub 2023 Feb 2.
It is common practice in agriculture to apply high‑carbon amendments, e.g. straw, or nitrification inhibitors (NI) to reduce soil nitrogen (N) losses. However, little is known on the combined effects of straw and NI and how seasonal soil temperature variations further affect N immobilization. We conducted a 113-day mesocosm experiment with different levels of N-fertilizer application (N0: control; N1: 125 kg N ha; N2: 250 kg N ha) in an agricultural soil, amended with either wheat straw, NI or a combination of both in order to investigate N retention and loss from soil after a cooling-warming phase simulating a seasonal temperature shift, i.e., 30 days cooling phase at 7 °C and 10 days warming phase at 21 °C. Subsequently, soils were planted with barley as phytometers to study N-transfer to a following crop. Straw addition significantly reduced soil N-losses due to microbial N immobilization. Although carbon added as straw led to increased NO emissions at high N fertilization, this was partly counterbalanced by NI. Soil cooling-warming strongly increased ammonification (+77 %), while nitrification was suppressed, and straw-induced microbial N immobilization dominated. N immobilized after straw addition was mineralized at the end of the experiment as indicated by structural equation models. Re-mineralization in N2 was sufficient, but still suboptimal in N0 and N1 at critical times of early barley growth. N-use efficiency of the N tracer decreased with fertilization intensity from 50 % in N1 to 35 % in N2, and straw amendment reduced NUE to 25 % at both fertilization rates. Straw amendment was most powerful in reducing N-losses (-41 %), in particular under variable soil temperature conditions, but NI enforced its effects by reducing NO emission (-40 %) in N2 treatment. Sufficient N-fertilization coupled with straw application is required to adjust the timely re-mineralization of N for subsequent crops.
农业中通常采用施加高碳改良剂（如秸秆）或硝化抑制剂（NI）来减少土壤氮素损失。然而，人们对于秸秆和 NI 的综合效应知之甚少，也不清楚季节性土壤温度变化如何进一步影响氮素固定。我们在农业土壤中进行了为期 113 天的中观实验，在不同氮肥施用量（N0：对照；N1：125 kg N ha；N2：250 kg N ha）下，添加或不添加小麦秸秆、NI 或两者的组合，以研究冷却-升温阶段（30 天冷却阶段温度为 7°C，10 天升温阶段温度为 21°C）后土壤中氮素的保留和损失。随后，将土壤种植大麦作为植物指示剂，以研究氮素向后续作物的转移。秸秆的添加显著减少了由于微生物氮固定导致的土壤氮素损失。尽管添加的碳（以秸秆的形式）导致高氮施肥时的硝态氮排放增加，但这在一定程度上被 NI 抵消了。土壤冷却-升温强烈增加了氨化作用（增加 77%），同时硝化作用受到抑制，秸秆诱导的微生物氮固定占主导地位。正如结构方程模型所表明的，秸秆添加后固定的氮在实验结束时被矿化。在大麦生长早期的关键时期，N2 中的再矿化虽然充足，但在 N0 和 N1 中仍不理想。随着施肥强度的增加，N 示踪剂的氮利用效率从 N1 中的 50%降低到 N2 中的 35%，而秸秆添加将氮利用效率降低到两个施肥率下的 25%。在变温条件下，秸秆添加在减少氮素损失（-41%）方面最为有效，但在 N2 处理中，NI 通过减少硝态氮排放（-40%）来增强其效果。为了调整随后作物的氮素及时再矿化，需要进行充足的氮肥施加并添加秸秆。
