creation of longitudinal cracks in planting rows to enhance seedling emergence using a modified row crop planter

stand establishment in crusting soil is one of the main concerns in the production of crops with delicate seedlings such as cotton, onions and rape seed. crust breaking, maintaining soil moisture and adding chemical and organic amendments to soil are different methods to weaken soil strength and allow the shoots to emerge. these methods are not always successful because they depend on factors such as the skill and timing required for crust breaking, shortage of water in arid regions and slow increase of soil organic content. the development of natural desiccation cracks along the planting lines is a new technique that can create a route by which seedlings can emerge. in this study, a pneumatic row crop planter was modified to provide physical conditions conducive to the development of longitudinal cracks along planting lines. the modifications included a v-shaped pre-opener attached to the front of the main opener and a conical wheel that replaced the original flat wheel of the machine, causing machine to leave a shallow furrow on the planting lines. this allowed the formation of longitudinal cracks over 96% of the planting line, which brought about an emergence rate of 72% for cotton seedlings in well-prepared soil. this technique in row planting was then compared the emergence of cotton seedlings using the conventional method (seed broadcasting and crust breaking) on large plots in the isfahan region. results revealed that, by using 1/10 the seed used currently in the broadcasting method, a desirable stand establishment can be achieved without crust breaking or further thinning. this results in a more uniform stand distribution and 2,100,000 rials per hectare saving for growers in planting stage alone.