Chiselling and wheeling on sandy loam long-term no-tillage soil: compressibility and load bearing capacity

Abstract

Traffic on arable land is one of the main causes of soil compaction, threatening soil function and quality. The objective of this study was to evaluate tillage and wheeling effects on mechanical properties on Hapludalf soil. We evaluated four combinations of management system and wheeling traffic: 13 years of no-tillage (NT), NT compacted with additional wheeling (NTc), minimum tillage (chiselling) soil (MT), and MT compacted with additional wheeling (MTc). Soil bulk density (Bd), macroporosity (Mp), precompression stress (σp), compressibility coefficient (Cc), and relative deformation were determined in four soil layers. Soil with greater Bd had higher σp and lower Mp and Cc, where statistical significance varied depending on soil depth, tillage, and additional compaction. Soil tillage did not affect Bd, but Mp was lowest in the no-till pan layer (0.05–0.15 m), and additional compaction decreased Mp in deeper layers. Long-term NT had greater σp and Cc than MT soil, while wheeling increased σp and decreased Cc in MT, only in the upper layer. Four wheelings with 1.1 Mg wheel load on no-tillage soil and two wheelings with 3.2 Mg wheel load on chiselled-soil decreased Mp in deeper (down to 0.25–0.35 m) layers, but only high load increased σp and decreased Cc in upper layers of chiselled-soil. Surface compaction in conservation agriculture is a major issue, since soil mobilisation by soil tillage should be avoided.