META-ANALYSIS OF THE YIELD RESPONSE TO PHOSPHORUS FERTILIZATION BASED ON LONG-TERM FIELD EXPERIMENTS

Phosphorus (P) fertilizer recommendations in Germany and most other European countries are based on plant-available soil P contents and results from long-term field experiments. Site-specific conditions are often neglected, and consequently excessive P fertilizer rates have often been applied in the past decades. In this study, long-term field P fertilization experiments including relevant site and soil parameters were evaluated in order to analyze the yield response. The database comprises about 2000 datasets from 30 field experiments from Germany and Austria. Statistical evaluations using a classification and regression tree approach, and multiple linear regression analysis indicate that besides plant-available soil P content, soil texture and soil organic matter content have a large influence on the effectiveness of P fertilization. This study methodology can be a basis for modification and specification of existing P fertilization recommendations and thus contribute to mitigate environmental impacts of P fertilization.