Tillage and compaction effects on soil properties, root growth and yield of wheat during drought in a semi-arid environment

• Published in: Soil technology 1991-09, Vol.4 (3), p.233-253
• Main Authors: Holloway, R.E., Dexter, A.R.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Biological and medical sciences; Cropping systems. Cultivation. Soil tillage; Fundamental and applied biological sciences. Psychology; General agronomy. Plant production; Soil tillage; Tillage. Tending. Growth control
• ISSN: 0933-3630
• DOI: 10.1016/0933-3630(91)90004-7

The calcareous sandy loam soils of Upper Eyre Peninsula in South Australia exhibit high penetrometer resistance throughout the growing season in soils which rarely wet to field capacity. In this area, tillage is normally limited to the top 0.05 m of soil. During two drought years, 1987 and 1988, experiments were carried out with deeper tillage in an attempt to ameliorate a perceived soil compaction problem at two sites (Minnipa and Cungena). At one of the sites a further series of experiments was conducted in which replicas of the tillage experiments were recompacted by four passes of a large (11,800 kg) tractor before seeding. Deeper tillage with a chisel plough at Minnipa had no measurable effect on water use or root growth in the period of measurement, or on grain yield. Soil strength was reduced by tillage to 0.3 m, but tillage to 0.15 m did not remove a hard pan below normal tillage depth. The loosening effect of deeper tillage was not measurable in dry soils by anthesis. Deeper tillage at Cungena resulted in some enhancement of root growth and water extraction. Grain yields were increased by tillage to 0.3 m in both seasons. Soil strength was considerably reduced by deeper tillage. Differences which occurred in the tillage experiments in water extraction, rooting density and grain yields did not occur in the recompaction experiments, but recompaction reduced the soil strength differences induced by deeper tillage. Yields were similar in the tillage and recompaction experiments in 1987, but in 1988 the recompacted deeper tilled treatments tended to yield less than the corresponding treatments in the tillage experiment. Bulk density was reduced by deeper tillage and increased by recompaction, but densities were generally not excessive, despite high penetrometer resistance.