Three P
fertilisation regimes have been applied since 1972: no- P (P0 treatment) and different rates of P fertiliser (P1.5:
1.5 times the grain P export and P3: 3 times the grain P export). These fertilisation regimes have led to contrasted
levels of soil P supply. Only slight differences were observed between the P1.5 and P3 treatment for above-ground
biomass accumulation and grain yield. Conversely the grain yield was significantly reduced in P0 (−11%).