Deep ripping soil helps root development as it improves aeration and infiltration of rainwater. This allows deeper penetration and faster growth of plant roots.
Ripping can be done with a bulldozer or three-point linkage rippers on a tractor. On slopes, rip along contours to reduce erosion risk. On flatter sites, cross ripping on a grid layout will guard against windthrow (trees blowing over), which is caused by roots growing in one direction along a single rip line. Avoid bringing any clay subsoil to the surface.
Rip the planting lines to a depth of 40-60 cm or more if possible. Double ripping with rips 50-100 cm apart is very beneficial as it shatters the soil. The space between the rip lines will depend on your planting requirements. See spacing [jump link] for more information.
Ripping should be done in fairly dry conditions to optimise the shattering effect. Usually ripping before the autumn break is difficult with commonly available equipment, so ripping after the first autumn rains is the standard practice.
There is little advantage in ripping deep sands as water will readily penetrate to the roots of the seedlings. Deep cracking clay sites are not suitable either as they will crack along the rip lines in summer, exposing the plant roots to the drying air and pests.
In sites with heavy soils and for ripping undertaken for autumn plantings, firm after ripping by rolling the lines with a tractor. This will minimise disturbance to the soil and reduce the amount of weed seed able to enter the ripline. It will also reduce exposure of the young tree roots.
Trees should be planted between the rips. Where a single rip line is used trees should be planted on the shoulder of the ripline. Trees planted in the bottom of the ripline can get waterlogged in winter.