Agronomic Implications of Converter Basic Slag as a Magnesium Source on Acid Soils

Abstract

The feasibility of using converter basic slag (CBS) as a source of Mg for gypsum‐amended acidic soils was studied in a Plinthic Palexerult from western Spain. An experimental farm was established and the Ap horizon of the soil was amended with limestone (L), phosphogypsum (PG), or red gypsum (RG) to alleviate Al toxicity. The PG and RG were supplied at 8.0 and 8.8 Mg ha−1, respectively. In addition, the gypsum‐amended plots received either CBS at 0.9 Mg ha−1 or limestone at 1.1 Mg ha−1 We studied the effects of the treatments on the exchange complex, soil solution, and the biomass production of ‘Jabato’ wheat (Triticum aestivum L.) under field and greenhouse conditions. The CBS proved highly effective in replenishing Mg lost from the soil through application of gypsum amendments. In the field experiment, only the RG + CBS treatment resulted in a statistically significant increase of biomass production relative to the control. In the greenhouse experiment, all treatments resulted in significantly increased production relative to the control, the largest (26 times) by RG + CBS. The PG + CBS and RG + CBS treatments resulted in significantly increased production relative to PG + L and RG + L, which testifies to the favorable effect of the Mg supplied by CBS. Also, the treatments including RG resulted in significantly increased production with respect to those including PG; the increased productivity is tentatively ascribed to a potential toxic effect of Al–F ion pairs, which were more abundant in the soil solution of PG‐treated soil.