Contrasting lime and P fertilizer regimes over seven decades: effect on δ¹³C and total-C in a coarse sandy soil profile

Changes in the natural abundance of the stable carbon-13 isotope (δ¹³C) represent a tracer of soil C dynamics. We investigated the long-term effects of liming (0 to 12 Mg ha⁻¹) and P fertilization (0 and 15.6 kg P ha⁻¹ year⁻¹) on vertical δ¹³C distribution and soil C content in five layers to 1 m depth. Liming and P fertilization had only small effects on δ¹³C and soil C, whereas soil depth strongly influenced both. These results indicate that, in coarse sandy soils, isotope-based C3-to-C4 conversion studies can be interpreted without accounting for the effects of liming and P fertilization.