生物质炭与不同形态氮肥配施对黄绵土氮素矿化的影响
Effects of biochar additions combined with three nitrogen fertilizer levels on soil nitrogen mineralization in loessal soil

通过室内培养试验将生物质炭施用于西北黄土高原旱地土壤，旨在探讨不同形态化学氮肥施用下施用生物质炭对土壤氮素矿化速率及机氮库的影响。结果表明：(1) 施用化学氮肥会提高土壤机氮累积量，但会在机氮释放高峰过后显著降低氮素矿化速率；其中，施用酰胺态氮肥和铵态氮肥对土壤氮素的矿化抑制作用强于施用硝态氮肥。(2) 在机氮释放高峰过后，生物质炭的施用会显著降低施用酰胺态氮肥处理下的氨化速率、硝化速率及净氮矿化速率，降低幅度分别为64.9%，44.6%和47.7%，且其降低程度在较低土壤含水量水平大于较高土壤含水量，而对施用硝态氮肥和铵态氮肥显著影响。(3) 生物质炭的施用一定程度上降低了施用酰胺态氮肥和铵态氮肥处理下的机氮累积量，且在较低土壤含水量下机氮累积低于较高土壤含水量处理。综合考虑，旱地施用酰胺态氮肥或铵态氮肥配合施用生物质炭可以有效降低土壤机氮累积量，从而降低氮素损失的风险。
The laboratory experiment was conducted to investigate the impacts of biochar incorporation on soil nitrogen mineralization and the accumulation of inorganic nitrogen in loessal soil. The results illustrated that application of chemical nitrogen fertilizer significantly increased the accumulation of inorganic nitrogen in the soil and reduced nitrogen mineralization rates after the peak of inorganic nitrogen release. Compared with nitrate nitrogen fertilizer, amide nitrogen fertilizer and ammonium nitrogen fertilizer obviously reduced the nitrogen mineralization rate. Biochar additions reduced the ammonification, nitrification, net nitrogen mineralization rates by 64.9%，44.6%, and 47.7% after the peak of inorganic nitrogen release, repectively. Moreover, the inhibition effect of biochar on rates of nitrogen mineralization was high at low soil moisture content. However, there was no significant differences in nitrate fertilizer and ammonium fertilizers treatments. The biochar additions reduced cumulative inorganic nitrogen in either amide fertilizer or ammonium fertilizer treatment, especially under low soil moisture content. In summary, application of amide nitrogen fertilizer and ammonium nitrogen fertilizer combined with biochar reduced the accumulation of inorganic nitrogen efficiently, thereby reducing the risks of nitrogen losses.