Effects of Different Tillage and Cultivation Practices on Soil Moisture and Safflower Yield in Rotation with Wheat in Rainfed Regions

The aim of tillage practice is the improvement of seed germination condition, facility of root development and improvement of plant growth. For this reason we study the effect of different tillage practices on safflower yield in rotation with wheat in dry lands. This experiment was conducted in RCBD with 4 replications and 4 treatments for 3 years in a rotation with wheat-safflower system. The tillage treatment was carried out after wheat harvesting and included T1: moldboard plow to depth of 20 cm in soil in autumn, handle seedling and fertilizer and the disk harrow in spring,(control), T2: direct sowing with grain drills in spring, T3: using rotavator in autumn and spring planting with grain drills, T4: chisel plow, disk harrow in autumn and grain drills planting was done in spring. Our data showed that among the treatments the highest value of grain yield ,0.929 ton/ha, belonged to T4 and  the lowest value, 0.564 ton/ha, belonged to T1. According to the results of simple correlations, plant height and number of capitula in plant had more effects on yield in respect to other yield components. The highest soil moisture content in stem elongation stage ,23.76%, and blooming stage, 20.56, of safflower belonged to T4. At 0 to 30 cm of soil depth the minimum value of bulk density 1.158 g cm^-3, and the maximum gravimetric soil moisture in T4 were observed, while the greatest bulk density 1.259 g cm^-3, and the least amount of moisture content in soil belonged to T1 treatment and clay-size fractions. Bulk soil C mineralization was higher in the grazed regime compared to the ungrazed regime most likely because of higher organic C and POM under these conditions. Results revealed that C mineralization was higher in the sand and silt fractions with higher weight proportion in the bulk soil and a low degree of humification in all grazing regimes.