Effect of deep tillage on soil physical properties and maize yields on coarse textured soils

The effects of deep tillage on soil physical properties and maize yields were evaluated on a loamy sand soil in which the bulk density distribution did not show a distinct root-limiting soil zone. Sub-soiling, mould-board ploughing and deep digging to 45 cm were compared with conventional tillage with and without irrigation. The tillage operations slightly decreased the bulk density of soil at all working depths. Sub-soiling and deep digging decreased the soil penetration resistance in the 20–40-cm layer to one-tenth of that in the control. They induced deeper and greater rooting and increased profile water use compared with conventional tillage. Sub-soiling, mould-board ploughing and deep digging increased plant height by 30–35 cm and yielded 80–100% more stover and 70–350% more grain than the control in different experiments.