秸秆还田对玉米根际氨氧化微生物群落及红壤硝化潜势的影响

为探讨酸性红壤根际氨氧化微生物群落以及硝化作用对不同秸秆还田处理的响应，基于中国科学院鹰潭红壤生态实验站设置的秸秆还田长期试验平台(9年),采用荧光定量PCR和高通量测序技术，研究不同秸秆还田处理(不施肥(CK);氮磷钾肥(NPK);氮磷钾肥+秸秆(NPKS);氮磷钾肥+秸秆猪粪配施(NPKSM);氮磷钾肥+秸秆生物炭(NPKB))下玉米根际土壤氨氧化古菌(ammonia-oxidizing archaea, AOA)和细菌(ammonia-oxidizing bacteria, AOB)丰度和群落结构的变化，揭示了秸秆还田对根际氨氧化微生物群落结构和硝化潜势(potential nitrification activity, PNA)的影响机制。结果发现：相比CK和NPK处理，秸秆还田显著提高了土壤养分含量和硝化潜势，其中有机碳(SOC)、全氮(TN)、全磷(TP)、速效磷(AP)、速效钾(AK)、硝态氮(NO~-₃-N)和铵态氮(NH~+₄-N)含量显著增加，NPKSM处理对土壤肥力提升效果最佳。AOA的硝化潜势显著高于AOB,表明AOA...

Effects of straw returning on the ammonia-oxidizers and nitrification in the rhizosphere of maize in a red soil

In the present study, a 9-year field experiment was conducted to investigate the effects of straw returning on the rhizosphere ammonia-oxidizers and nitrification in a red soil. The field experiment included five treatments:no fertilizer, CK; chemical nitrogen, phosphorous and potassium fertilizer, NPK; NPK fertilizer and straw, NPKS; NPK fertilizer and straw combined with pig manure, NPKSM; NPK fertilizer and straw biochar, NPKB, which was located at the National Agro-Ecosystem Observation and Research Station in Yingtan. Here, the abundance and composition of ammonia-oxidizing archaea (AOA) and bacteria (AOB) in the rhizosphere of maize under different types of straw returning were examined by quantitative PCR and Illumina sequencing. The results found that the straw returning treatments significantly increased soil nutrient contents and potential nitrification activity (PNA) compared with the CK and NPK treatments, with the highest soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), available phosphorus (AP), available potassium (AK), nitrate nitrogen (NO₃^--N), ammonium nitrogen (NH₄⁺-N) and PNA under the NPKSM treatments. AOA-specific PNA (PNA_AOA) was significantly higher than AOB-specific PNA (PNA_AOB), which indicated that AOA dominated the nitrification in a red soil. The straw returning treatments presented significantly higher abundance and diversity (Shannon and Chao1 indices) of AOA and AOB community than the treatments without straw returning. Furthermore, the straw returning treatments significantly shaped the composition of AOA and AOB community. SOC, TN, NH₄⁺-N, as well as AOA and AOB diversity were significantly correlated with PNA_AOA and PNA_AOB, respectively. Structural equation modelling showed that NH₄⁺-N and TN indirectly affected PNA_total through the AOA abundance and AOB diversity. The results indicated that straw returning treatments could improve the abundance and activities of AOA and AOB community, and consequently promoted the process of nitrogen transformation, with the best improvement achieved by straw and pig manure application.