Sand over gravel soils have responded to ripping if the gravel is not a completely restrictive layer. However, the response of wheat crops to deep ripping is limited because the subsoil acidity restricts root growth and uptake of nutrients and water by the plant. Rainfall On responsive soils in the medium rainfall area, ripping will almost always produce responses in crop growth, but grain yield responses may be curtailed if there are poor finishing rains or soil moisture is restricted. Also, on suitable soils, responses to ripping have been least reliable in areas with less than 325 mm annual rainfall. In these areas, soil may not become wet deep down in the soil profile, and ripped or not, the roots have access to all the water available in the profile.
Crop species All cereals respond to deep ripping similarly.
On suitable deep sandy soils there have been consistent and very large responses to deep ripping. Figure 2 shows the variability over 46 trials conducted between 1981 and 1989 on yellow loamy sands from Tammin to Yuna. Of the 46 trials, yield has decreased in only two after deep ripping. Residual value of deep ripping The response to deep ripping can last for many years. Other benefits of deep ripping The soils that respond to deep tillage are sandy, so they are likely to be groundwater recharge areas.