摘要：

为研究南方红壤区农田氮肥减量和硝化抑制剂双氰胺(DCD)对土壤酸化的阻控效果,特别是土壤硝化作用产生的H⁺对土壤酸化的影响,设置4个不同的氮素调控处理的小白菜盆栽试验(不施肥(NF)、常规施肥(CF)、氮肥减量(NFR)、常规施肥+DCD(CF+DCD)),测定土壤基本理化性质、硝化势、AOA和AOB的amoA丰度,探讨了NFR和DCD施用对土壤酸化和硝化作用的影响。结果表明:相比于CF(pH=4.25;铵态氮:97.6 mg/kg;硝态氮:46.6 mg/kg),NFR和DCD的施用均可以显著提升土壤pH 值0.21,0.42,显著增加土壤铵态氮含量13.0,27.5 mg/kg,同时显著降低土壤硝态氮含量22.8,44.9 mg/kg。与CF(20.68 mg /(kg·d))相比,NFR硝化势并无显著区别,CF+DCD硝化势显著降低20.3 mg /(kg·d)。不同处理土壤AOA和AOB的 amoA丰度存在显著差异,与CF(AOA:1.33×10⁵拷贝/g;AOB:34.55×10⁵拷贝/g)相比,NFR和DCD的施用均显著增加AOA amoA丰度125.56%,353.08%,显著降低AOB amoA丰度25.64%,97.83%。AOA与土壤交换性氢铝、表观硝化率呈极显著负相关关系,与pH值呈显著正相关关系;相反,AOB与土壤硝化势、表观硝化率、硝态氮呈极显著正相关关系,与土壤pH值呈极显著负相关关系。综上所述,施用NFR和DCD提高了土壤pH值,降低了土壤交换性酸度,缓解土壤酸化,同时通过抑制AOB的数量进而抑制硝化作用,降低硝态氮的潜在环境风险。DCD施用效果更佳,在改良土壤酸化方面具有应用价值。

关键词: 红壤, 土壤酸化, 氮素调控, 硝化抑制剂, 酸化阻控

Abstract:

To investigate the effects of nitrogen(N)reduction and the nitrification inhibitor dicyandiamide(DCD)on mitigating soil acidification in red soil regions of Southern China,a pakchoi pot experiment was conducted with four N management treatments:no fertilizer(NF),conventional fertilizer(CF),reduced N fertilizer(NFR),and conventional fertilizer plus DCD(CF+DCD).Soil physicochemical properties,nitrification potential(NP),and amoA gene abundances of ammonia-oxidizing archaea(AOA)and bacteria(AOB)were measured.The results showed that,compared with CF(pH 4.25;NH₄⁺-N 97.6 mg/kg;NO₃^--N 46.6 mg/kg),NFR and DCD application significantly increased soil pH by 0.21 and 0.42,respectively,increased NH₄⁺-N content by 13.0 and 27.5 mg/kg, and decreased NO₃^--N content by 22.8 and 44.9 mg/kg. Relative to CF(NP:20.68 mg/(kg·d)), NFR did not significantly alter NP,whereas CF+DCD significantly reduced NP by 20.3 mg/(kg·d).AOA and AOB amoA abundances differed significantly among treatments:compared with CF(AOA:1.33×10⁵copies/g;AOB:34.55×10⁵copies/g), NFR and DCD significantly increased AOA-amoA abundance by 125.56% and 353.08%, and significantly decreased AOB-amoA abundance by 25.64% and 97.83%,respectively. Correlation analysis revealed that AOA-amoA abundance was highly significantly negatively correlated with exchangeable H⁺and Al³⁺acidity and with apparent nitrification rate, and significantly positively correlated with soil pH. In contrast,AOB-amoA abundance exhibited highly significant positive correlations with nitrification potential, apparent nitrification rate,and NO₃^--N content,and a highly significant negative correlation with soil pH.In conclusion,NFR and DCD application alleviated soil acidification by increasing pH and reducing exchangeable acidity.This effect was primarily achieved through suppression of AOB abundance and nitrification activity,thereby reducing the potential environmental risk of nitrate accumulation.DCD exhibited superior performance,highlighting its application value for ameliorating soil acidification.

Key words: Red soil, Soil acidification, Nitrogen regulation, Nitrification inhibitor, Acidification mitigation

中图分类号: 

• S143化学肥料