Publication Date

1985

Location

Kyoto Japan

Description

We conducted studies which assessed soil phosphorus (P) status and responses to P fertilization in five pasture types of varying longevity. The main objective was to determine if current recommendations for P fertilizer on pastures, as based on P fertilization response studies in ungrazed small-plot studies, are suitable. In two of the five pasture types, soil P was at levels such that yield response from applied P was insignificant. Plant tissue P concentration was increased but was not a good indicator of P fertility needs. Soil P was both concentrated in areas of the pasture extending to 30 m from watering sites and in the upper 0-75 mm of the soil. We concluded that pasture studies where P fertility initially is non-limiting can not be used to derive practical recommendations any more suitably than can the rates of P fertilization deemed optimal in ungrazed small-plot studies. We suggest periodic sampling for soil test P along with P fertility response studies within pastures as a procedure to more accurately assess P fertility levels in research studies which compare with on-the-farm conditions.

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Varying Phosphorus Fertilization with Pasture Type and Longevity

Kyoto Japan

We conducted studies which assessed soil phosphorus (P) status and responses to P fertilization in five pasture types of varying longevity. The main objective was to determine if current recommendations for P fertilizer on pastures, as based on P fertilization response studies in ungrazed small-plot studies, are suitable. In two of the five pasture types, soil P was at levels such that yield response from applied P was insignificant. Plant tissue P concentration was increased but was not a good indicator of P fertility needs. Soil P was both concentrated in areas of the pasture extending to 30 m from watering sites and in the upper 0-75 mm of the soil. We concluded that pasture studies where P fertility initially is non-limiting can not be used to derive practical recommendations any more suitably than can the rates of P fertilization deemed optimal in ungrazed small-plot studies. We suggest periodic sampling for soil test P along with P fertility response studies within pastures as a procedure to more accurately assess P fertility levels in research studies which compare with on-the-farm conditions.