[Variation of the exchange mineral nutrient content (Ca + Mg +K) Na and Al in a cropping sequence managed with two nitrogen sources, urea and sodium nitrate]

abonos potasicos aluminio aluminium andosol andosoles andosols avena sativa calcio calcium contenido mineral cultivo secuencial engrais potassique fertilisation fertilizer application magnesio magnesium mineral content nitrate de sodium nitrato de sodio potash fertilizers potasio potassium potassium sulphate sequential cropping sodio sodium sodium nitrate sulfate de potassium sulfato de potasio triticum urea uree