Performance of two hoe-type air drills sowing green peas in a conservation tillage system

A one year experiment was conducted in eastern Oregon to evaluate the performance of two different types of hoe-type air drills in terms of seeding depth uniformity, emergence, early plant growth, and crop yield when sowing green peas (Pisum sativum L.) in a tilled, leveled field. The seeding systems studied included a banded-row, flex frame air drill with seeding depth controlled by frame elevation and a single-row air drill with individual seeding unit depth control. Experimental design was a randomized complete block design with four replications. At the time of seeding, the field had approximately 5.6 t/ha of winter wheat (Triticum aestivum L.) residue on the soil surface. Depth of seed placement and date of emergence were recorded for 998 plants, while crop yield was determined by hand harvesting a 9.2-m² area. Despite the significant differences in drill configuration, few differences in performance were found. The banded-row, flex frame air drill without individual depth gauge wheels placed seeds as accurately as the single-row air drill equipped with individual seeding unit depth control. Standard deviation of the mean seeding depth, speed of emergence index, and the percentage of sown seeds that emerged were not significantly different between the two drills. Crop yield and crop yield components including plant population, pods per plant, peas per pod, and pea weight were also not significantly different. The results of this study suggest that in leveled field conditions, there is no benefit to drills equipped with individual seeding unit depth control in terms of seed depth uniformity, seedling emergence, stand establishment, or crop yield.