Residue management practices and planter attachments for corn production in a conservation agriculture system

Seed placement and failure to establish a uniform plant stand are critical problems associated with production of corn (Zea mays) following wheat (Triticum aestivum) in a conservation agriculture system in Iran. Our objectives were to evaluate the performance of a corn row- crop planter equipped with two planter attachments (smooth/toothed coulters) at six wheat residue management systems (three tillage systems and two levels of surface residue) at two forward speeds of 5 and 7 km h-1. Residue retained after planting, seeding depth, emergence rate index (ERI) and seed spacing indices were determined. The baled residue plots tilled by chisel plow followed by disc harrow (BRCD) resulted in minimum residue after planting as compared to other residue treatments. Furthermore, the maximum values of the ERI and uniformity of plant spacing pertained to this treatment. Other results showed that the ERI increased up to 18% for the toothed coulter as compared to the smooth coulter. The toothed coulter also established a deeper seed placement as compared to the smooth coulter. Planting at forward speed of 5 km h-1 resulted in deeper seeding depth as compared to a forward speed of 7 km h-1. However, lower values of miss and precision indices were obtained at forward speed of 7 km h-1, indicating a more uniformity of plant spacing. Results of this study showed that equipping the conventional planter with toothed coulter and planting in soil prepared under the BRCD residue management system can result in a satisfactory conservation crop production system.