Effect of different tillage methods on soil bulk density, soil porosity, soil moisture content and yield of wheat under dryland condition

In order to study the effect of tillage methods on soil bulk density, soil porosity, soil moisture and yield of wheat an experiment as a complete block design with 4 replications was counducted in ICARDA from 1985-86 to 1997-98 growing season. Tillage methods were: no tillage, sweep, moldboard and chisel plough. Results showed that in depth of 0-10 cm of soil, moldboard had lower bulk density than other tillage methods but in 10-20 cm of soil depth, no tillage treatments had the highest bulk density. In 20-30 and 30-40 cm of soil depth,sweep had the highest bulk density compared with other tillage methods. However, in 0-10 cm of soil surface, moldboard had higher porosity than other tillage methods. In 10-20 cm of soil depth, no tillage had the lowest porosity and in 20-30 and 30-40 cm of soil depth, sweep had the lowest porosity. Soil moisture content in 1987-88 growing season, that was a wet season, in all tillage methods in all dates of samplling was not significant, but in 1989-90 growig season which was a dry season the differences in soil moisture content between tillage methods were significant.In this growing season in all dates of samplling, soil in moldboard treatment compared with the other treatments had the lowest moisture and no tillage had the highest. In 1992-93 growing season, a moderate season, also soil moisture content in moldboard treatment the lowest. Biological, straw and grain yield in all years in no tillage treatment was significantly lower than the other tillage methods, however, there were no significant differences between sweep, chisel and moldboard.