Cereal grain yield responses to deep ripping on duplex soils

Abstract

The relationship between the thickness of the sandy A horizon and grain yield responses to deep ripping of wheat and barley was studied on the south coast sandplain of Western Australia. Thirty-five sites with duplex soils, with variable thickness of the sandy A horizon were ripped to 30 cm, while 15 sites were also ripped to 20 cm. There was a positive linear regression (R2 = 0.63) between grain yield response to 30 cm ripping and the thickness of the sandy A horizon. Ripping to 30 cm resulted in economical returns, provided the A horizon was greater than 31 cm thick. Ripping into the clay B horizon was of no benefit. The average response to 30 cm ripping was 15% (230 kg/ha). Grain yield was positively related (R2 = 0.43) to depth of ripping on those sites where the sandy A horizon was more than 39 cm thick. Ripping to 20 cm was economic on soils with a sandy A horizon greater than 20 cm thick.