Réponse du soya à la fertilisation minérale en éléments majeurs NPK sur des sols classés de riches à excessivement riches en phosphore ou en potassium des Basses Terres du Saint-Laurent

In the scientific literature there are numerous studies on soybean response to major mineral NPK elements. But there are few research data on this topic for the Lowland soils of the Saint-Lawrence Valley. A 3-yr study was conducted in 1994, 1995, and 1996 on three representative soil types of the lowland Saint-Lawrence Valley region: Dujour, Sainte-Rosalie and Saint-Urbain. These soils are classified from rich to excessively rich in available phosphorus and potassium as measured by the Mehlich 3 method. Results of this study indicate that yield is rarely significantly influenced by levels of nitrogen, phosphorus or potassium fertilization. Moreover, there are no significant interactions among those elements and soybean grain yield. Other observed variables (specific weight, grain visual quality, 100-seed weight, seed protein and oil contents) were generally not affected by the different levels of nitrogen, phosphorus or potassium fertilization. There were few significant interactions between major elements and those variables. Generally, soybeans did not respond to NPK mineral fertilization on representative soils of the Lowland Saint Lawrence Valley region classified from rich to excessively rich in available phosphorus and potassium. Key words: Soybean, fertilization, nitrogen, phosphorus, potassium, yield