Effect of subsoiling on soil physical properties and dry matter production on a Brown Soil in Southland, New Zealand

Abstract

This study examined the effect of shallow subsoiling on soil physical properties and ryegrass‐white clover pasture production on a Waikiwi silt loam (Brown Soil) over 2.5 years. Macroporosity, hydraulic conductivity, and air permeability were measured in 6‐cm increments down to 30 cm soil depth. The topsoil was loosened by pulling both conventional tines or wing‐shaped tines set at 50 cm apart through the soil, at a depth of 25–30 cm. Subsoiling increased macroporosity by up to 39% of the soil volume, and increased saturated hydraulic conductivity and air permeability by up to two orders of magnitude. Improvements in soil physical conditions were evident for up to 2 years after subsoiling with both the winged tines and conventional tines, although there were few differences between the tine types. Some recompaction and settling over time occurred in the upper 12 cm of the soil profile. For the second year, the conventional tine subsoiling treatment reduced total production by 9%. Pasture dry matter production for the winged tine subsoiling treatment was variable with no significant differences in total production compared with non‐subsoiled controls.

Keywords:

• compaction
• Southland
• treading
• subsoiling
• soil physical properties
• macroporosity