A miniaturised bionic electronic nose system was developed to solve the problems of expensive equipment and long response time for soil pesticide residue detection. The structure of the bionic electronic nasal cavity is designed based on the spatial structure and olfactory principle of the sturgeon nasal cavity. Through experimental study, the structure of the nasal cavity of the sturgeon was extracted and analyzed. The 3D model of the bionic electronic nasal cavity was constructed and verified by Computational Fluid Dynamics (CFD) simulation. The results show that the gas flow distribution in the bionic chamber is more uniform than that in the ordinary chamber. The airflow velocity near the sensor in the bionic chamber is lower than in the ordinary chamber. The eddy current intensity near the bionic chamber sensor is 2.29 times that of the ordinary chamber, further increasing the contact intensity between odor molecules and the sensor surface and shortening the response time. The 10-fold cross-validation method of K-Nearest Neighbor (K-NN), Random Forest (RF) and Support Vector Machine (SVM) was used to compare the recognition performance of the bionic electronic nasal cavity with that of the ordinary electronic nasal cavity. The results showed that, when the bionic electronic nose detection system identified the concentration of pesticide residues in soil, the recognition rate of the above three recognition algorithms reached 97.3%, significantly higher than that of the comparison chamber. The bionic chamber electronic nose system can improve the detection performance of electronic noses and has a good application prospect in soil pesticide residue detection.

The degradation of soil structure in black soils has become a key factor limiting the productivity of farmland ecosystems. However, systematic studies on restoring soil physical properties and improving crop yields through biological tillage remain scarce. In this study, Eisenia fetida was employed as a biological tillage agent to create soil macropores. An orthogonal experiment with three factors was conducted to investigate the mechanisms by which different gradients of soil moisture, decomposed straw, and soil compaction affect soil pore structure and the yield of Brassica chinensis L. X-ray-computed tomography (CT) was used to quantitatively characterize the macropore network mediated by earthworms. The results indicated that the critical threshold conditions for optimized biological tillage were 50 g of decomposed straw, a compaction of 50–150 kPa, and a soil moisture content of 30–37%. Under these conditions, earthworm activity significantly enhanced the leaf dry weight of Brassica chinensis L. by approximately 55.29%, while root dry weight increased by 96.60%. Compared with treatments of low soil moisture combined with 50 g of decomposed straw, higher moisture levels further increased total biomass by 75.46%. Compared with the control, earthworm-induced macropores had 27 times more pore throats than abiotic pores, and network models showed significantly improved connectivity, indicating enhanced soil structure. This study revealed a synergistic threshold of water–food–physical resistance regulation for soil structural improvement under biological tillage and innovatively proposed a biological tillage evaluation system based on CT-quantified pore networks and root structure–function relationships. These findings provide a theoretical basis for the ecological restoration of degraded black soils.

Black soil, as a vital environment for food production, is currently facing severe degradation. Earthworm tillage is recognized as an effective approach to improving black soil structure; however, its optimal implementation strategy remains unclear. In this study, a pot experiment using Pak Choi (Brassica rapa L. ssp. chinensis) was conducted under an orthogonal design with three factors—earthworm size, application timing, and quantity. Combined with yield measurement, analysis of variance (ANOVA), and grey relational analysis (GRA), the effects of earthworm application on plant growth and soil structure were systematically evaluated. In addition, Computer Tomography (CT) scanning and three-dimensional reconstruction were employed to visualize the pore structures of representative soil samples. The results showed that large earthworms significantly enhanced both leaf and root biomass of Pak Choi, exhibiting a stronger promoting effect than small earthworms. Application at the sowing stage resulted in the greatest yield improvement, whereas applications at other growth stages had limited effects. The number of earthworms did not show a statistically significant impact under the experimental conditions, and its potential influence requires further verification under more refined density gradients. Overall, this study elucidates the mechanisms by which earthworm tillage improves soil structure and promotes crop growth, providing a theoretical basis for the restoration and sustainable utilization of degraded black soil.