Root Pruning (chisel tining) creates a larger slit under the soil than solid tine spiking, therefore giving a bigger surface area to 'breathe', at the same time this will cut roots, encouraging new roots to grow, promoting strong leaf growth. It is usually carried out in Winter and Spring.
This is a very underrated operation on domestic lawns, mainly because many of the machines available do not offer this option. Bowling greens and many sports pitches will normally be slit tined on a regular basis during Autumn, Winter and Spring. Many experienced greenkeepers will tell you that the thorough work carried out in the dormant months will make a good strong, deep rooted green for the following Summer. The same technique can be applied to domestic/amenity turf.
Please contact me if you would like additional information about lawn root pruning in Wells, Somerset.