减氮配施抑制剂及鸡粪提高尿素氮在稻田土壤中的转化及利用

  【目的】  探究氮肥减量配施氮肥抑制剂和鸡粪的情况下土壤及肥料氮素供应和利用状况，及其对土壤肥力和水稻产量的影响，为我国东北地区水稻生产中提高氮肥利用效率、实现节肥增效提供理论基础。  【方法】  采用15N同位素示踪技术，盆栽试验设不施氮肥处理 (CK)、常规氮肥 (15N示踪尿素) 处理 (N)、80%尿素氮+20%鸡粪氮处理 (NM)、80%尿素氮+抑制剂处理 (NI)、80%尿素氮+抑制剂+20%鸡粪氮处理 (NIM)。测定不同生长时期来自于土壤及肥料中的铵态氮、微生物量氮含量及植株含氮量，收获时测定水稻产量。  【结果】  1) NI处理在土壤及肥料来源的铵态氮供应能力方面与N处理相当，抑制剂添加对氮肥减施有一定的补偿作用。在分蘖期和灌浆期，NM处理供氮能力优于无机氮肥处理。NIM处理在铵态氮和硝态氮供应能力方面效果最好。与N处理相比，NIM处理在水稻返青期、分蘖期和灌浆期土壤铵态氮含量分别提高了19.2%、66.3%和36.5%，硝态氮含量分别提高了13.9%、12.7%和17.3%，15NH₄+-N含量在分蘖期增加了14.59 mg/kg。2) 无机氮肥处理 (N、NI) 对土壤微生物量碳含量无显著影响，但添加鸡粪处理 (NM、NIM) 显著提高了返青期和灌浆期土壤微生物量氮含量 (P < 0.05)。与N处理相比，NIM处理在水稻返青期、分蘖期、灌浆期和成熟期土壤微生物量碳含量分别提高了32.61%、29.23%、53.46%和2.85%，微生物量氮含量分别提高了147.98%、22.97%、133.33%和24.63%，15N-微生物量氮含量在分蘖期增加了约22.56 mg/kg。3) 抑制剂及鸡粪添加均提高了水稻产量和生物量，NIM处理的水稻生物量、产量和吸氮量较N处理分别提高了83.59%、124.18%和46.66% (P < 0.05)，土壤中肥料氮的残留量显著增加了56.48%，肥料氮的损失减少了约78.7%。NIM处理的氮素吸收利用率、氮肥农学效率等显著高于其他处理，抑制剂与鸡粪在提高肥料氮素利用率方面存在显著交互作用。  【结论】  在我国北方棕壤水稻土上，在尿素中添加抑制剂 (1%PPD+1%NBPT+2%DMPP) 或者用鸡粪替代20%的尿素均能改善土壤氮素供应，氮肥减量20%配施抑制剂和鸡粪不仅不会减产，还会在提高水稻产量的同时提高肥料利用率。从肥料氮释放及水稻吸收利用的角度综合考量，减少20%尿素投入，添加氮肥抑制剂，以及添加氮肥抑制剂的同时，用鸡粪替代20%的尿素的效果较好。

Combining N-inhibitor and chicken manure with reduced N fertilizer to improve the conversion and utilization of fertilizer N in a paddy soil

  【Objectives】  The nitrogen supply and utilization of soil and fertilizer-derived N were studied under the condition of reduced urea N input and combined with N-inhibitors and chicken manure, to provide a theoretical basis for rice cultivation in Northeast of China, in terms of improving the nitrogen use and fertilizer efficiencies.   【Methods】  15N isotope tracer technology was adopted in a rice pot experiment. The five treatments included: no nitrogen fertilizer control (CK), conventional rate of urea (urea-15N), 80% urea N + 20% chicken manure N (NM), 80% urea N+ inhibitor (NI), 80% urea N + inhibitor + 20% chicken manure N (NIM). The contents of ammonia nitrogen and microbial biomass N in soil and urea-derived nitrogen, and nitrogen content of rice plant at different growth stages were analyzed, investigated the rice yield was investigated.  【Results】  1) NI treatments had considerable soil ammonium N and fertilizer derived N supply ability compared with N treatment, inhibitors had a compensatory effect on nitrogen reduction. NM treatment had markedly higher N supply ability at the tillering and filling stages, compared to N treatment. Compared with N treatment, soil NH₄+-N in NIM treatment increased by 19.2%, 66.3%, and 36.5%; NO₃?-N content increased by 13.9%, 12.7%, and 17.3% at returning green, tillering and filling stage, respectively, 15NH₄+-N content increased by 14.59 mg/kg at tillering stage. 2) N and NI treatments had no significant effect on soil microbial biomass carbon (MBC) content, however, NM and NIM treatments significantly improved soil microbial biomass N (MBN) content at the returning green and filling stage (P < 0.05). Compared with N treatment, the MBC content in NIM treatment increased by 32.61%, 29.23%, 53.46% and 2.85%, and the MBN content increased by 147.98%, 22.97%, 133.33% and 24.63% at the returning green, tillering, filling and mature stages, respectively, while 15N-MBN increased by 22.56 mg/kg at the tillering stage. 3) N-inhibitor with chicken manure addition increased the rice yield and biomass. Compared with N treatment, NIM increased the biomass, yield and nitrogen uptake of rice by 83.59%, 124.18% and 46.66%. It also significantly increased fertilizer N residue in the soil by 56.48% and reduced the fertilizer N loss by 78.7%. Compared with N treatment, NIM treatment had a significant effect on N absorption and utilization of fertilizer, and its N absorption, N utilization rate and N agronomic efficiency were significantly higher than other treatments.  【Conclusions】  For brown paddy soil of northern China, the addition of inhibitor (1% PPD+1% NBPT+2% DMPP) and chicken manure could replenish soil N supply. Based on 20% reduction in urea, augments with the application of inhibitors and chicken manure increased the fertilizer utilization rate and increased the rice yield. From the perspectives of fertilizer N release and utilization in rice, NI and NIM treatments shows superior agronomic performances.