Edafología. Volumen 7-3. Septiembre 2000. pág 301-312.
To study the effect of different P fertilizer doses on production and nutritional factors, a randomized block experiment with 5 treatments levels (0, 50, 125, 250 and 600 kg P2O5 ha-1) was performed in four sites differing in the initial P status (measured as Olsen P).
The critical P Olsen values above which the response to P fertilizer application can be considered recuce was around 14 mg kg-1. Total P in plants at the clearing state above 3500 mg kg-1 and water extractable P in plants at the same stage above 2500 mg kg-1 were not related to any increment in root and sugar yield with inreasing P fertilizer doses.
Interactions between nutrients were only significants in two of the studied sites. Zn concentration in plant tissues decreased as the fertilizer dose increase in two sites form the Marisma of Lebrija at the clearing state, meanwhile this effect was observed 30 days after clearing in the Villamartin site.