technical and economical comparison of tillage implements used for crust breaking of saffron cultivation at different irrigations times

crust breaking of saffron is an important operation at the first stage of growth that should be accuratly operated as in this period sprouts of saffron rise up to near the soil surface. after primary irrigation, farmers soften the soil surface by means of different cultivation implements, which enables saffron flowers arise from subsurfarce. this research was conducted to compare tillage implements with no crust breaking method for three-times irrigations (early, on time, late) technically and economically. in this research,therefore, three-time irrigations were selected as three expriments and horizontal factors were: a) no crust breaking b) animal plow c) manual crust breaking using a local tool (chahar shakh) d) rotivator with special blades. this research performed at the farm of saffron and medical plants research station planted three years ago. it was concluded that for the early irrigation experiment tillage implements did not have significant effect on yield at the first year, but manual crust breaking and no crust breaking had significant difference at the second year. regarding the effect of time of irrigation manual crust breaking and rotivator factors produced saffron yield higher than no crust breaking and animal plow factors with significant difference. at the late irrigation experiment, the highest yield was related to both no crust breaking and manual crust breaking factors and there were significant differences between no crust breaking and manual crust breaking factors and also between rotivator and animal plow factors. economical evaluation showed that using rotivator would be the best method for early and on time irrigation, and the suitable method for late irrigation was no crust breaking.