沼液替代化学氮肥对滨海稻田土壤有机氮和细菌群落的影响

李瑞; 张巡; 杨阳; 汤逸帆; 申建华; 韩建刚

doi:10.11674/zwyf.2021658

沼液替代化学氮肥对滨海稻田土壤有机氮和细菌群落的影响

Effects of substituting biogas slurry for chemical nitrogen fertilizer on soil organic nitrogen and bacterial communities in coastal paddy fields

摘要

摘要:
目的明确沼液替代化肥对稻田土壤有机氮(SON)矿化的影响及其与土壤微生物群落变化的关系。
方法田间试验于2017年在江苏滨海稻田上进行，在总氮投入量225 kg/hm²的前提下，设置4个沼液替代化肥氮比例：0%、33%、66%、100% (即，BS0、BS33、BS66、BS100处理)。试验连续进行3年后(2019年)，取土测定了有机氮的矿化特征，分析有机氮中酸解氮、非酸解氮、酸解铵态氮、氨基酸态氮、氨基糖态氮、酸解未知态氮的含量及细菌组成结构。
结果与BS0处理相比，BS66处理的土壤氮矿化势(N₀)增幅最大，达39.7%。氨基酸态氮和非酸解氮含量沼液施用处理有显著升高(P<0.05)，BS66处理的氨基酸态氮较BS0增加了39.2%，BS100处理的非酸解氮含量增加了73.9%。沼液替代化肥提高了土壤Chloroflexi (绿弯菌门)与Actinobacteria (放线菌门)的相对丰度，显著降低了Nitrospirae (硝化螺旋菌门)的相对丰度(P<0.05)。不同细菌属对沼液替代化肥水平的响应差异较大，随着沼液替代化肥比例的上升Subgroup_6_unclassified的相对丰度增加；而Subgroup_17_unclassified的相对丰度则呈下降趋势；KD4-96_unclassified的相对丰度在BS33处理下降低而在BS66处理及BS100处理下升高；沼液替代化肥模式下新增了相对丰度≥1%的细菌属Subgroup_7_unclassified。冗余分析结果显示，土壤N₀与Thermodesulfovibrionia_unclassified呈极显著负相关(P<0.01)，非酸解氮与Subgroup_6_unclassified呈显著正相关(P<0.05)，而与Betaproteobacteria_unclassified呈显著负相关(P<0.05)，氨基酸态氮与Proteobacteria_unclassified、氨基糖态氮与KD4-96_unclassified呈显著正相关(P<0.05)，酸解未知态氮和Desulfarculaceae_unclassified呈显著负相关(P<0.05)。
结论沼液替代化肥改变了土壤微生物群落结构，增加了土壤氮库容量，显著提高了土壤氮矿化势，增强了土壤供氮能力。

Abstract:
Objectives We studied the effects of biogas slurry on soil organic nitrogen (SON) mineralization in paddy fields and its relationship with the change in soil microbial community.
Methods The field trials were conducted on Jiangsu coastal rice fields in 2017. Four levels of biogas slurry N application were set with constant total nitrogen input (225 kg/hm²) at 0%, 33%, 66% and 100% (BS0, BS33, BS66, BS100). After 3 years of continuous treatment (2019), soil samples were collected to determine the mineralization characteristics of SON. The content of total hydrolyzable N, non-hydrolyzable N, ammonium N, amino acid N, amino sugar N, unknown N in SON and the structure of bacterial composition were analyzed.
Results BS66 treatment recorded higher soil potential mineralizable organic N (N₀) (39.7%) than BS0 treatment. Both amino acid N and non-acid hydrolysis N contents increased with biogas slurry application (P<0.05). BS66 treatment had a higher increase in amino acid N (39.2%) and and BS100 had a higher increase in non-acid hydrolysis N (73.9%) than BS0 treatment. The substitution of fertilizers with biogas slurry increased the relative abundance of Chloroflexi and Actinobacteria, and decreased the relative abundance of Nitrospirae (P<0.05). The bacterial genera exhibited a varying response to substituting fertilizers with biogas slurry. As the ratio of biogas slurry to chemical fertilizers increased, the relative abundance of Subgroup_6_unclassified increased and Subgroup_17_unclassified decreased. The relative abundance of KD4-96_unclassified decreased under BS33 treatment and increased under BS66 treatment and BS100 treatment; Subgroup_7_unclassified had a relative abundance ≥1% due to the replacement of chemical fertilizer with biogas slurry. The results of RDA showed that soil N₀ and Thermodesulfovibrionia_unclassified had a significant negative correlation (P<0.01), non-acid hydrolysis nitrogen had a positive correlation with Subgroup_6_unclassified (P<0.05), and a significant negative correlation with Betaproteobacteria_unclassified (P<0.05). Amino acid nitrogen and Proteobacteria_unclassified, amino sugar nitrogen and KD4-96_unclassified were all positively correlated (P<0.05). The unknown nitrogen and Desuslfarculaceae_unclassified were significantly negatively correlated (P<0.05).
Conclusions The substitution of biogas slurry for chemical fertilizers changed the structure of the soil microbial community, increased soil nitrogen storage capacity, improved soil nitrogen mineralization potential, and enhanced soil nitrogen supply capacity.

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