Agriculture increases the bioavailability of silicon, a beneficial element for crop, in temperate soils

Crops may benefit from silicon (Si) uptake in soil, but plant-available Si (PAS) is influenced by both natural weathering and anthropogenic drivers such as agriculture. The soil parameters controlling PAS remain poorly documented in temperate climates. Using an extensive French topsoil dataset and CaCl2-extractable Si (SiCaCl2) as a PAS proxy, this study shows that cultivation increases SiCaCl2 in soils developed on sediments (73% of France), largely due to liming in slightly acidic to acidic non-carbonated sedimentary soils. Analyses of non-cultivated soils indicate SiCaCl2 increases with the < 2 µm fraction and with pH, but only where the < 2 µm fraction ranges from 50 to 325 g kg−1, likely reflecting clay mineralogy and iron oxide content. An estimated 4% of French soils used for wheat cultivation could be deficient in SiCaCl2.