Effects of Different Tillage Methods on Soil Bulk Density, Yield, and Yield Components of Rain-fed Wheat

Effects of different tillage systems on soil bulk density، yield، root growth and nutrient uptake by wheat grain and straw was investigated using an experiment with a completely randomized block design. The experiment had 5 tillage treatments in 4 replications and was carried out in the Research Farm of Gorgan University of Agricultural Sciences and Natural Resources، during the growing season of 2008-09. Tillage treatments were: Moldboard plough at 20-25 cm depth followed by one disc harrowing (MP); Rotary cultivator at 12-17 cm depth (RP); Disc harrowing at 8-10 cm depth (DH); Chisel plow at 25-30 cm depth (CP); and No-tillage (NT). Results showed that، throughout the growing season، the lowest and the highest soil bulk densities at 0-8 cm depth occurred with MP and NT treatments، respectively. At 8-16 cm depth، however، the lowest soil bulk density was observed with MP treatment، except for the stages before tillering and at harvesting stage. Soil bulk densities at 0-8 and 8-16 cm depths gradually increased during growing season in all tillage methods. This increase was less in no-tillage than the other tillage methods. The highest and the lowest values of root weights were obtained with MP and NT treatments، respectively، in stages before tillering and at harvesting stage. The highest nutrient uptake by gain and straw was found in MP treatment with maximum yield. MP raised grain and straw yield by 65. 9% and 58. 61%، respectively، relative to NT. Therefore، MP is suggested as the most appropriate tillage method for optimizing production resources (land، moisture، and soil nutrients).