Lignin has long been considered a relatively stable component of soil organic matter. However, recent studies suggest that lignin may turn over within years to decades in
arable soil. Here we analyzed lignin concentrations in an 18 year field experiment under continuous silage maize where two soils were sampled at six points in time. Our
objectives were to examine the long-term dynamics of (i) lignin derived from a previous C3-vegetation and (ii) lignin derived from maize, as influenced by two levels
of maize biomass input. Total lignin concentrations in soil were quantified by gas chromatography of lignin cupric oxide oxidation products. Compound-specific 13C isotope analysis allowed discrimination between C3-derived lignin and maize-derived lignin. Degradation dynamics of C3-derived lignin were independent of biomass input
level, suggesting that priming did not affect soil lignin concentrations over almost two decades. After 18 years approximately two thirds of the initial C3-derived lignin
remained in the soils, whereas, on average, 10 % of the recent maize-derived lignin input was retained. We suggest that lignin is effectively stabilized in these arable
soils, although the mechanisms involved remain unclear.