科研之友
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摘要
Objective: To date, the responses of the soil ecosystem stability to soil disturbance after long-term no-tillage practice are still unknown. In this study, soil nematodes were served as a model to study the response of soil nematode community structure to before and after disturbance under a long-term no-tillage practice, so as to provide a scientific support for the rational selection of farming measures in the black soil area of Northeast China. Method: Two different phases of long-term no-tillage practices, including no-tillage (NT) and disturbed no-tillage (DNT), were set up on a black soil experimental station of Northeast Institute of Geography and Agricultural Ecology, Chinese Academy of Sciences, Dehui City, Jilin Province. Before planting the crops, the soil samples collected from the 0-15 cm soil layer were used to isolate and identify the nematodes. Using the conventional tillage (CT) as the control, the effect value (lnR) was calculated to measure the effect size of NT and DNT on the number of genus and the abundance and ecological index of nematodes under different rotation systems (corn-soybean rotation, CS; corn continuous cropping, CC). Principal component analysis (PCA) and redundancy analysis (RDA) were used to determine the composition of soil nematode communities and their driving factors among different tillage practices. Result: Compared with CT, NT had a positive effect on the abundance of omnivores-predators across crop rotation systems, while DNT significantly (P<0.05) improved the genus number and abundance of bacterivores, the abundance of fungivores and the total nematodes under CS, and exerted negative effects on the genus number and abundance of all nematode trophic groups under CC. The composition of nematode community of NT and DNT was completely different from that of CT, and the main driving factors were total nitrogen content and bulk density, which could explain 10.5% and 11.4% of the variation in nematode community, respectively. In addition, compared with CT, NT significantly (P<0.05) increased the value of structure footprint (Fs) across all crop rotation systems, while DNT significantly (P<0.05) decreased almost all ecological indexes (except the maturity ratio of free-living nematodes to plant-parasitic nematodes, MI/PPI). Furthermore, the decrease degree of ecological index varied with crop rotation systems. CS instead of CC exerted a significant positive effect on MI/PPI. Conclusion: Long-term no-tillage practice could form a relatively stable soil nematode community structure in all crop rotation systems. This stability was easily gone away with the soil disturbance, including mouldboard ploughing and the removal of residues. However, crop rotation could mitigate the instability caused by soil disturbance.
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