Surface application of lime ameliorates subsoil acidity and improves root growth and yield of wheat in an acid soil under no-till system

Crop root growth and grain yield can be affected by chemical modifications in the soil profile due to surface lime application. A field trial was carried out on a loamy dystrophic Typic Hapludox at Ponta Grossa, State of Parana, Brazil, to evaluate root growth and grain yield of wheat (Triticum aestivum L. cv. CD 104, moderately susceptible to Al), about 10 years after surface liming (0, 2, 4, and 6 Mg ha(-1)) and three years after surface re-liming (0 and 3 Mg ha(-1)), in a long-term no-till cultivation system. Soil acidity limited wheat root growth and yield severely, probably as a result of extended water deficits during the vegetative stage. Surface liming caused increases up to 66% in the root growth (0-60 cm) and up to 140% in the grain yield. Root density and grain yield were correlated positively with soil pH and exchangeable Ca2+, and negatively with exchangeable Al3+ and Al3+ saturation, in the surface and subsurface layers.