The stabilization of soil organic carbon (SOC) promoted by conservation agriculture (CA) depends on soil aggregation. Aggregation protects SOC and creates heterogeneous microhabitats hosting diverse soil biota which in turn promote aggregation. A long-term experiment, studying the interaction of tillage with nitrogen (N) fertilization on a soybean-wheat rotation, was used to investigate eukaryotic community diversity, composition, and structure within small macroaggregates (sM) and occluded microaggregates (mM). Using high-throughput Illumina sequencing, we found (i) a different eukaryote diversity response to management intensification across soil aggregates and soil depths; (ii) a conserved core community composition of eukaryotes across CA treatments and aggregates at surface and subsurface layers; (iii) a different effect of tillage on eukaryotic community structure in sM and mM along the soil profile according to N availability; (iv) a positive association of protists, and fungi with the amount of sM and mM, and their SOC content; (v) a stronger complexity of within- and cross-domain networks (eukaryotes and eukaryotes-prokaryotes) in mM than in sM at surface layer. Overall, our findings demonstrate for the first time that protists together with fungi play major roles in soil structuring and C cycling, and that Cercozoa represent hubs in soil biota aggregate networks.

保护性农业 (CA) 促进的土壤有机碳 (SOC) 稳定取决于土壤团聚。聚集保护 SOC 并创造异质微生境，容纳不同的土壤生物群，进而促进聚集。一项长期实验，研究了大豆-小麦轮作中耕作与氮 (N) 施肥的相互作用，用于研究小型大团聚体 (sM) 和封闭微团聚体 (mM) 内的真核生物群落多样性、组成和结构。使用高通量 Illumina 测序，我们发现 (i) 不同的真核生物多样性对土壤团聚体和土壤深度的管理集约化反应；(ii) CA 处理中真核生物的保守核心群落组成以及地表和地下层的聚集体；(iii) 耕作对沿土壤剖面 sM 和 mM 真核生物群落结构的不同影响，取决于 N 可用性；(iv) 原生生物和真菌与 sM 和 mM 的量及其 SOC 含量呈正相关；(v) 在 mM 中，域内和跨域网络（真核生物和真核生物-原核生物）的复杂性比表面层的 sM 更强。总体而言，我们的研究结果首次表明，原生生物和真菌在土壤结构和碳循环中发挥着重要作用，而尾蚴代表了土壤生物群聚体网络中的枢纽。(v) 在 mM 中，域内和跨域网络（真核生物和真核生物-原核生物）的复杂性比表面层的 sM 更强。总体而言，我们的研究结果首次表明，原生生物和真菌在土壤结构和碳循环中发挥着重要作用，而尾蚴代表了土壤生物群聚体网络中的枢纽。(v) 在 mM 中，域内和跨域网络（真核生物和真核生物-原核生物）的复杂性比表面层的 sM 更强。总体而言，我们的研究结果首次表明，原生生物和真菌在土壤结构和碳循环中发挥着重要作用，而尾蚴代表了土壤生物群聚体网络中的枢纽。