| Abstrakt: |
Positive crop growth response to deep tillage in sandy soils has been observed in Imperial Valley, California. Very little information is available, however, on the effect of different deep tillage operations and the possible causes of the beneficial effects of deep tillage. The present field study was conducted on a stratified fine sandy soil to evaluate the effect of subsoil chiseling and slip plowing to a depth of 90 cm on wheat (Triticum aestivumL.) yield and soil properties. Conventional soil disking to 20 cm depth was compared with two subsoil chiseling and two slip plowing treatments. Subsoil chiseling was on 1‐m centers in one and in two directions, and slip plowing was on 2‐m centers in one or two directions. The two directions of deep tillage were at right angles to each other. Significant increases in wheat yield resulted from deep tillage. Grain yield (metric tons/ha) were: 4.50 for disking; 5.15 for subsoil chiseling in two directions; 5.73 for slip plowing one direction; and 6.32 for slip plowing in two directions. Along the silts formed by the subsoil and slip plow as compared with areas between slits or areas disked only: (a) stratified sandy soil layers were more disturbed, (b) root and shoot growth and water intake rate were significantly increased, (c) soil strength was significantly decreased, and (d) bulk density decreased in some layers but not in others. Following subsoil chiseling and slip plowing of the fine sandy soils in Imperial Valley, reduction in soil strength apparently enhanced root penetration in the soil. More information is needed to clarify the effects of other factors such as bulk density changes, water movement and nutrient distribution in the soil profile. |
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