Long-term effects of lime and gypsum additions on no-till corn and soybean yield and soil chemical properties in southern Brazil

A long-term experiment on a clayey, kaolinitic, thermic Rhodic Hapludox where dolomitic lime was applied to the surface (either at 4.5 t/ha or at 1.5 t/ha per yr for 3 yr), or incorporated into the topsoil (4.5 t/ha), and gypsum applied to the surface (3, 6, and 9 t/ha), was carried out to evaluate their effects on soil profile chemical properties and yields of corn (Zea mays L.) and soybean (Glycine max L. Merrill). Lime applied to the soil surface at either full or split rates, or incorporated and surface-applied gypsum had long-lasting effects on soil acidity or calcium and sulphur availability respectively, as measured 8 yr after application. Grain yields of corn and soybean were not influenced by liming. Gypsum at 9 t/ha significantly increased corn grain yields by 7 and 8% respectively 7-10 yr after application, but did not affect soybean grain yields. The differences in response of the corn and soybean crops to gypsum might be related to the Ca2+ uptake by plants because of cation exchange properties of roots, being smaller for corn than for soybean. The use of gypsum in no-till systems becomes more viable when corn is grown with a greater frequency in crop rotation.