Effects of subsoil loosening on soil physical properties, plant root growth, and pasture yield

Subsoil loosening of an 8‐year‐old dryland pasture soil (Templeton silt loam) at either of two depths (27 or 47 cm) resulted in a significant ( P < 0.1) decrease (>10%) in soil bulk density and a concomitant increase in soil porosity compared with undisturbed soil. The hydraulic conductivity of the loosened soil was significantly (P < 0.05) greater than that of the undisturbed soil, reflecting the increased pore continuity within the depth of loosening. These more rapid drainage rates resulted in a drier soil profile at the start of spring, 10 months after subsoil loosening. These improved soil physical conditions permitted more rapid root growth and the development of a more extensive pasture root system with a significantly (P < 0.1) greater (36%) root length below 30 cm depth. Subsoil loosening resulted in significant increases in pasture production over the first 3 months of spring (August‐October).