Abstract

The current sugar beet fertilizer applications in Morocco are based on sugar beet fertilization experiments and soil testing, to assess the soil fertility, carried out in different regions. There is a need to develop soil test interpretation norms developed under local pedoclimatic conditions in order to make precise fertilizer recommendations for each farmers plot. Eight sugar beet fertilization experiments were conducted on farmer’s plots in two major sugar beet producing regions of Morocco; Doukkala region and Tadla region. Four phosphorus rates of 0, 22, 44, and 66 kg P.ha^-1 were applied at planting as triple superphosphate in a completely randomized bloc design with four replications. Sugar beet responded to the phosphorus input at three out of the eight locations. The results showed that if Olsen’s soil available P test isngreater than 16 mg P.kg^-1, no fertilizer P application for sugar beet is necessary because it will have no effect on the productivity of the sugar beet. On the contrary, this contribution constitutes a waste of financial resources. Gross marginal return from P fertilizer application increased with relative sugar beet root yield improvement. Sugar beet economical optimum P fertilizer rate requirement varied from 0 to 60 kg P.ha^-1, depending of soil P Olsen level. The very good correlation between soil available P level and sugar beet P requirement rate allows for better P fertilizer recommendations for this crop. Indeed, available P tests performed before planting are currently used for making fertilizer P recommendations for sugar beet for farmers in these regions