Assessment of Irrigated Cotton Seedling Emergence in Flatland Mechanized Planting Systems

Abstract

The nonuniform emergence of cotton seedlings in the flatland mechanical planting method is a major problem in cotton production areas with crust-forming soil and saline soil and irrigation water. A field study was conducted in central Iran within Isfahan Province to assess the effects of four types of planting equipment and three crust breaking methods on cotton (Varamin cultivar) emergence on a clay loam soil. Four items of planting equipment were used, consisting of: a cotton planter with runner opener and its smooth-crown zero pressure pneumatic press wheels positioned along or away from the seed row; a cotton planter with runner opener and open-center concave steel press wheels; and a grain drill with disk opener and without covering device. Three crust breaking methods were employed, including rolling cultivator, rolling-type crust breaker (two spike-tooth drums in tandem) and no crust breaking. The crust breaking operations were done one week after the first irrigation when the first seedlings had emerged. Final emergence, planting depth, plant height and soil strength were measured.The choice of planting equipment had significant effects on planting depth, final emergence and plant height. The cotton planter with its press wheels positioned along the seed row had the greatest level of seedling emergence in a non-crust breaking treatment. This is because, during the planting operation, the soil was very dry and the press wheels were firming the soil above or around the seed to the degree that enough seed-soil contact was provided and the seeding depth was decreased. In non crust-breaking treatments, the emergence was less than 50%. The difference in emergence for the rolling cultivator and the rollingtype crust breaker was not significant. However, the rolling cultivator could be recommended due to its availability in the region. Results indicated that the grain drill (with acid delinted cotton seed) or alternatively the cotton planter with open-center press wheels (with undelinted seed) could be used with the rolling cultivator as a crust breaker as a mechanized cotton dry flatland planting system in this region.