Combinations of ripping depth and tine spacing for compacted sandy and clayey soils

Soil compaction is one of the major problems facing modem intensive agriculture. To remove soil compaction and restore soil productivity soil must be ripped to loosen it. Ripping is a costly process involving high fuel consumption, as well as depreciation of the implements through wear and tear. This article shows research into some combinations of tine spacing and ripping depth and their consequences for soil properties and grain yields. Three sites were chosen for these experiments on clayey and sandy soils. Treatments were a factorial of three tine spacings (20, 30 and 40 cm) by three ripping depths (15, 30 and 40 cm) together with the control. Commercial gypsum at 2.5 t/ha was applied to all treatments to maintain soil structure after ripping and the treatments were treatments were monitored for two seasons under wheat and barley crops. The highest grain yield in sandy soil was found with the combination of 40 cm ripping depth and 20 cm tine spacing. In clayey soils tine spacings of 20 cm and 30 cm in combination with 40 cm ripping depth, were equally effective for grain yield. The shallowest depth treatment, 15 cm, did not significantly affect grain yields regardless of tine spacing. It seems that the best practical compromise of tine spacing and ripping depth is 30 cm x 30 cm. The highest stored soil water was obtained from the deepest ripping and the widest tine spacing (40 cm x 40 cm) treatments and the lowest was obtained from the shallowest depth and narrowest spacing (15 cm x 20 cm) treatments which was still higher than the control treatment. However, due to soil re-settlement and re-compaction, the soil water storage obtained in the year after ripping to 40 cm depth was in many cases only equal to that obtained from 30 cm ripping depth. Soils ripped at 30 cm or deeper had significantly higher water infiltration rate than soils ripped at 15 cm depth. Soil bulk density, though decreased significantly in all ripping treatments relative to the controlled treatments in the first year, showed no stable pattern of change in the second year. All shallow ripping treatments (15 cm) regardless of tine spacing had similar soil strength and were not significantly different from the control. The other two ripping depths in general were equal, and significantly better than the controls. It is concluded that ripping to 30 or 40 cm depth in combination with 30 or 40 cm tine spacing was most effective for treating compacted soils. Crown Copyright (c) 2008 Published by Elsevier BX All rights reserved.