Long-term effects of 100 years of vineyard-to-apple orchard conversion on soil structure, chemistry, and biodiversity

Abstract Background and Aims Long-lasting changes in soil biodiversity and chemistry reflecting past land use are commonly found during the conversion between natural and agricultural systems . However, no clear pattern can be seen when rotating crops are established. Most studies focus on arable systems and over short-term rotations, neglecting longer-term tree-crop successions. We hypothesised that converting one long-term tree crop to another would retain a stronger relationship between soil chemistry, biodiversity, and agricultural history. Methods We selected a unique agricultural field enclosed in less than one hectare and characterised by three similar neighbouring sites where viticulture was replaced by apple cultivation in 1922, 1970 and 2016. This specific agronomic context allowed us to investigate the possible long-term effect of tree-crop succession on soil chemistry and soil biodiversity (Bacteria, Fungi, Animalia, and Protozoa), avoiding biases due to pedo-climatic variability. Results Our results indicate the soils are physicochemically and biologically distinguishable based on tree-crop conversion. Mainly, we identified a decrease in clay and silt from 1922 to 2016, alongside a decline in keystone species, while microbial and animal communities grouped in three clear different clusters. Nevertheless, no significant changes were observed in soil functionality, likely due to the high functional redundancy within microbial communities. Conclusion Our findings highlight the lasting impact of tree-crop conversion, underscoring the importance of considering long-term agricultural history when assessing soil agricultural management.