4.1. Effect of treatments on restored soils (Technosols)
Natural soils have a somewhat larger sand content than soils (Technosols) from the experimental plots because because the parent material has some influence of a nearby mixed slope deposit containing elements from a calcareous sandstone.
On the opposite, natural soils have a lower CaCO3equivalent and clay than those from experimental plots. Two facts explain such difference: a) both the marl substrate and the topsoil have higher content of carbonated silty particles from the marl while the natural soil has some influence from the nearby calcareous sandstone containing part of quartz sand grains; b) natural organic matter, has had time enough to contribute by acidification to solubilize part of carbonates as stated by many authors, e.g. Ramnarine et al (2012).
The Technosols from the marl substrate have a larger CaCO3 equivalent content than those from the topsoil which was formed by mixing the marly substrate with stripped topsoil from an area with some calcareous sandstone influence.
It is worth noting that in similar restored soils from the same area (Luna et al, 2017, 2018) the combination compost-woodchips had improved soil structure, higher transmission pores and aggregate stability values, and woodchips alone contributed effectively in reducing surface runoff and soil erosion even with no amendments.