Does no-tillage mitigate the negative effects of harvest compaction on soil pore characteristics in Northeast China?

Optimizing tillage management is one way to reduce the risk of soil compaction due to traffic load in Northeast China. In this study, we aimed to examine the responses of precompression stress (& sigma;pc), compression index (Cc), pore morphology (>30 & mu;m), air-filled porosity (& epsilon;a60), air permeability at matric potential of -60 hPa (ka60) and saturated hydraulic conductivity (Ks) to harvest traffic on soil from two contrasting tillage practices using a 10-yr old field experiment. After the crop was harvested with a combine harvester, undistributed soil cores were collected in the 0-10 and 10-20 cm layers from non-traffic and traffic zones of no-tillage (NT) and moldboard plough (MP) plots. In the non-traffic zone, the MP management showed greater total porosity (& epsilon;total), & epsilon;a60 and macroporosity (& epsilon;X-ray) than the NT. There were no differences in pore connectivity, mean pore size and ka60 of the 0-10 cm layer and in Ks of the 0-20 cm layer between the two tillage practices, however, more biopores were observed under NT. Harvest traffic showed no significant effects on NT soil. In the MP plots, the & epsilon;total, & epsilon;X-ray, and pore connectivity, were decreased and pores larger than 0.15 mm were preferentially compacted. As a result of traffic, MP soil displayed lower ka60 in the 0-20 cm layer and lower & epsilon;X-ray and connectivity in the 10-20 cm layer. In the NT management, the pore system had greater water and air conduction efficiencies and stable properties. Thus, compared to MP, NT can mitigate the negative effects of harvest compaction on soil in Northeast China.