Row cleaners enhance reduced tillage planting of corn in Iran

Seed placement and failure to establish a uniform plant stand are critical problems associated with conservation tillage production of corn (Zea mays) following wheat (Triticum aestivum) in Iran. Our objectives were to evaluate the performance of a conventional corn planter (with runner type openers) equipped with row cleaners and to demonstrate for local farmers an affordable method for reduced tillage corn production. The reduced tillage system studied consisted of disking followed by chisel plowing and another disking ahead of planting. A ground-driven row cleaner was fabricated and mounted to each unit of a common pneumatic single seed planter and used to plant at three forward speeds (4, 7, and 10 km h−1) into no- (NR), half- (HR), and whole- (WR) residue plots. This compares to a typical system of complete removal or burning the previous wheat residue in the region. The amount of residue retained in the row, depth of seed placement, emergence rate and three indices of uniformity in seed spacing were determined. Row cleaners performed best at the highest forward speed, retaining an average residue cover of 920 kg ha−1 compared to 1350 kg ha−1 for plots planted without using row cleaners. This 430 kg ha−1 more residue removal was a significant improvement with regard to soil–seed contact. For the HR and WR plots, residue removal averaged 45% and 70% of that present before planting, suggesting that the row cleaners will work more effectively at high residue conditions. Without row cleaners, initial residue levels resulted in a shallow planting depth, but when row cleaners were used, planting depth was maintained near the target depth (5 cm). The desired planting depth was also obtained at 7 km h−1 in the HR plots. Row cleaners significantly increased plant emergence rate with the maximum (3.5 plants d−1 m−1) being observed for seeds planted at 4 km h−1 in the HR plots. This agrees with others who showed high residue reduces plant emergence and grain yield. Planting with row cleaners into HR plots at 7 km h−1 resulted in the lowest miss and precision indices comparable to those of a no-residue plot (16.5% and 17.5%, respectively), and a quality of feed index as high as 69% was obtained at similar conditions. Our results indicate that equipping available planters with row cleaners can result in a successful reduced tillage corn production system and thus satisfy both farmers and authorities promoting conservation tillage. In addition to the environmental benefits of the proposed system, it is expected that the savings in time, fuel and labor would offset the cost of row cleaners.